CA2104443C - Apparatus for receiving and displaying color television signals having different formats - Google Patents
Apparatus for receiving and displaying color television signals having different formatsInfo
- Publication number
- CA2104443C CA2104443C CA002104443A CA2104443A CA2104443C CA 2104443 C CA2104443 C CA 2104443C CA 002104443 A CA002104443 A CA 002104443A CA 2104443 A CA2104443 A CA 2104443A CA 2104443 C CA2104443 C CA 2104443C
- Authority
- CA
- Canada
- Prior art keywords
- television signal
- television
- color
- signal
- corrected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
- H04N9/3105—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3179—Video signal processing therefor
- H04N9/3182—Colour adjustment, e.g. white balance, shading or gamut
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/64—Circuits for processing colour signals
- H04N9/642—Multi-standard receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/64—Circuits for processing colour signals
- H04N9/73—Colour balance circuits, e.g. white balance circuits or colour temperature control
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Processing Of Color Television Signals (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Abstract
A projection-type display apparatus having a lamp which emits a high intensity white light, two dichroic mirrors which filter out the three primary color beams from the white light and three liquid crystal panels which, respectively, modulate the color beams according to the three color image signals. Characteristics of the lamp and the dichroic mirrors are set so that the reproduction chromaticity range includes transmission chromaticity ranges of both the NTSC and HDTV systems. The image signals are supplied to two types of linear matrix circuit which are, respectively, suited for the NTSC and HDTV systems in order to correct color reproduction errors. The output of the linear matrix circuits are selected according to the system of the received television signal.
In addition, a display white color temperature is set in the corrected image signals according to the system. Thus, the image signals are supplied to a display device such that the colors of the image can be accurately reproduced.
In addition, a display white color temperature is set in the corrected image signals according to the system. Thus, the image signals are supplied to a display device such that the colors of the image can be accurately reproduced.
Description
2 1 ~ 3 APP~RA~U8 FO~ R~ vlN~ AND DI8~L~YIN~
COLOR TE~E~ O~ 8I~ Xa~I~ D~BR~N~ FORM~8 D OF T~ INV~N~I~N
The present invention generally relates to the color television field, and more particularly, is directed to a color television receiver which is capable of receiving and displaying color televi~ion ~ignals broadca~t with different transmission specification~ and formats. The receiver pe~its accurate reproduction and display of the color picture information contained in the received television signal without regard to its transmission speci~ication or ~ormat.
r -~ D 0~ ~E T~V~N~O~
In ~he NTSC teleuision signal system, which i8 the system presently in use in the United States ,and in many ok~er countries, the tr~n~ 3ion specifications and format wer~ esta~lished in order t~ maxi~ize the amount of red ~R), green (G) and blue (B) primary col~r in~or~ation which can be transmitted in the tel~vision signal. Thus, the NTSC specifications and format provide wide chromaticity ranges in order to insure transmission of .
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full color content for the television image.
Television rec~ivers known in the prior art reproduce the color image con~ained in the television signal by adding and mixing the red, green, and blue primary color information extracted ~rom the television signal. However, the chrom~ticity ranges of a typical television receiver is narrower than the chromaticity ranges present in the received television signal. Thu~, full and faithful reproduction of the ~olor picture information contained in the television signal is not possible in televi ion receivers known in the prior art.
Figure 1 is a CIE (Commission International de Enluminure) chromaticity diagram illustrating the red, green and blue primary color chromaticity values for the NTSC sy~tem, the phosphor in a cathode ray tube (CRT) used in the typical television receiver and the color filter in a liquid crys~al display device (LCD), also now commonly used in small portable television receivers and large projection-type television displays. The NTSC chromaticity values are represented by the ~Ache~ line, the CRT chromaticity values are represented by th dot-dash line and the LCD values are represented ~y the solid line. The chromaticity values charted in Flgure 1 are set forth below in table form: .
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2~0~3 N~SC CR~' LCD
X Y X ~ X Y
R: 0.670 0.330 0~657 0.338 0.613 0.334 G: 00210 0.710 0.2~7 0.609 0.233 0.627 B: 0.140 0.080 0.148 0.054 0.140 0.079 The outer bold line in Figure 1, and associated numbers at the indicated points on the line, illustrate the spectrum locus and wave-lenqths (nm). In the NTSC system here, C light having a color temperature of 67~4 K is used as a referenc2 white light W with the following chromaticity:
W : X = 0.3101, Y = 0.3163 In the NTSC system, if the chromaticity values ~or the three primary color~ for the display ~CRT or LICD) in the receiver are set to the s~me as the NTSC values, the co.lor picture information in the tran3mitted television signal can be ~aithfully reproduced on the receiver display by setting the reierence white light to the c~romaticity of C light. Howev~r, a color television receiver must also b~ capable of receiving and displaying black and white television signals. Therefore, in order to achieve the requisite compatibility with black and white television broadcasts, a white color light with higher chromaticity values than C light must be x,. ~
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2104~3 used as the reference.
In addition, the chromaticity values for the primary colors for a television receiver depends on the phosphor chro~aticities oP
the CRT or LCD which, as described above and shown in Figure 1, are different than the chromaticity values for the primary colors for the NTSC system. Therefore, if corrections are not made ~or the differences between the NTSC and receiver chro~aticity values, color errors will result and the color picture information contained in the television signal will not be faith~ully reproduced on the display in the receiver.
Moreover, and as also discussed above, the chromaticity ranges of the CRT and LCD are narrower than the NTSC chromaticity ranges.
Thus, the color reproduction range of the television receiver i5 not brvad enough to reproduce all o~ the color information contained in the ;nc ing television signal~ The~efore, even when the appropriate color corrections are made with respect to differencs~ in the NTSC and display chromaticity ~alues, the receiver is still not capable of faithful reproduction of every color received in the inc. ;ng television signal.
The types of color reprcduction errors discus~ed above are also referenced on page 959 in the book entitled "The New Color -... : :: ... . . ... - :
.. .~ . . . .
2 1 ~ 3 Science Handbook" which was published in Japan.
Figure 2 i~ a UV chromaticity diagram showing the color reproduction errors described above and referenced in the above mentioned handbook. The solid line triangle in Figure 2 indicate~
the chromaticity range for the primary colors of the NTSC system on the transmis~ion side of the television signal. The dashed line triangle illustrates the chromaticity range of the primary coiors of the CRT phosphor at the receiver. Note that while the NTSC a~d CRT ranges greatly overlap, the NTSC range is slightly larger and each of its values are shifted from the corresponding values in the CRT range. The graph in Figure 2 is obtained by calculating the color reproduction error based on the differences between the NTSC
ancl CRT chromaticity ranges. An example of some of the NTSC
chromati~ity values are shown by the dots in Figure 2. In order to correct color reproduction errors in the display, these values must be shifted in order to bring them into a corresponding point in the CRT chromaticity range as indicated by the arrows in Figure 2.
In CRT television receivers and color cameras, linear matrix circuits are used to correct color reproduction errors. Figure 3 is a block diagram showing a linear matrix oircuit which corrects such color reproduction errors. The G (green), B (blue) and R
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(red) primary color signals are supplied to input terminals 1, 2 and 3, respectively, and to gamma cancellation circuits 4, 5 and 6 so that transmission gamma is cancelled by removing the ga~ma correction which was added to the signal on the image transmission side.
The output signals ~rom gamma canc~llation circuits 4, 5 and 6 are supplied to matrix circuit 7 which is formed of coe~ficient circuits 8 to 16 and adders 17 to 1~. Matrix circuit 7 multiplies the supplied R, G and B signals by respective corre~tion matrix coefficients and then adds them together. Coefficient circuits 8 to 16 can be formed o~ simple circuits using resister~ as is known in the art. Gamma addition circuit:s 20, 21 and 22 add the transmission gamma to the respective corrected R, G and B color signals and outputs them via terminal~s 23, 24 and 25 as primary color signals Rl, Gl, and Bl. In this way, color reproduction errors are r~ :ved and approximatQly the same colors as in the transmitted image can bs re~Lo~uced at the receiver. However, the correction is possible only for colors in the region in which the solid line triangle and the ~he~ line triangle in Figur~ 2 overlap each other.
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2 ~ 4 3 Recently, there have been test broadcasts of a high definition television (~DTV) signal format which is capable of displaying high quality television images. Taking into account the popularity of the existing NTSC television system, and the large installed base of such equipment, television receivers which are capable of receiving images in both the NTSC and HD~Y system formats are being made commercially available. ~owever, the transmission specific~tions of an HDTV system are different from those o~ an NTSC system. In the HDTV transmission specification and format, th~ R, G and B primary color chromaticîties are as follows:
R: X - 0.640, Y = 0.330 G: X = 0.300, Y - 0.600 13: X = 0.150, Y = 0.0~) Also in the HDTV specification, D~ lis~ht is used as a reference white color and its chromaticity W Ls as follows:
~ : X = 0.3127, Y = 0.3290 Figur~ 4 is a ClE chromaticity diagram showing the NTSC
specification values and the HDTY specification vales of thP
respective R, G and B primary color chromaticities. As Figure 4 indicates, the chromaticity value ~or G in the NTSC syst~m is .j, . ~ - .
:.
.
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-~4~43 greatly dif~erent than the chromatic:ity value for G in t~e HDTV
system. Note, however, that the chromaticity value for G in the HD~V system is comparatively close to the chromaticity value for G
in CRT and LCD displays (see Figure 1). There~ore, in a television receiver which uses a C~T or LCD, there is comparatively little color reproduction error when receiving and displaying a HDTV
broadcast. There is, however, a likelihood of large color reproduction errors when receiving an NTSC broadcast as is apparent from Figure 1.
When correcting color reproduction errors for one system in a television receiver which is capable of receiving multiple system formats ~such NTSC and HD~V) in which the three primary color chromaticity values differ from one system to the other, color reproduction errors in the other systems cannot be corrected~
Television P~OYLamS produced by the HDTV system and commercial feature ~ilms are sometimes bro~r~cted using the NTSC system.
Faature ~ usually are produced in accordance with specifications established by the Society o~ ~otion Pictura and Television Engineers (SMPTE~. The HDTV system also i5 set to conform to SMPTE specifications.
Eigure 5 is a CIE chromaticity diagram showing the ,' :
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.9_ transmission primary color chromaticity values for both the SMPTE
and NTSC systems. As is apparent from Figures 4 and 5, the transmission primary color chromaticity values for the HDTV system approximately coincides with those of the SMPTE system. Also, the PAL and SECAM television signal transmission systems are nearly standardized to the EBU specifications~ The transmission primary color chromaticity values for thase systems also approximately coincide with those of the HDTV system There is presently known in the art an HDTV to NTSC system converter which enables reception of HDTV broadcasts on a standard NTSC system television receiver. With such a converter, or other equipment having similar functions as that of the converter, it is possible to also convert other signal f'ormats, such as SMPTE, PAL
and SECAM to NTSC for display on a standard NTSC receiver. However, the transmission gamma of the NTSC syste~ dif~ers from the transmission ga~ma of any one of the other systems.
Figure 6 is ~ ~raph illustra~ing transmission gamma. The solid line shows the gamma curve of the SMPTE system and the dashed line shows the gamma curve of the NTSC system (~ = 0~45~ s shown in Figure 6, the black side values in particular differ between the NTSC and the SMPTE systems. Due to the difference between the -. ~ . : .
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gamma curves, the rendering of the black gradations sometimes is unnatural depending on the signal source of the broadcast program. For instance, even within the same broadcast program, the gradation rendering differs according to the difference in the signal source, namely in accordance with 5 the specification under which the program was produced.
In addition to television receivers which use a CRT or liquid crystal display, recently projection-type color television receivers have been developed in order to provide large-screen viewing. Projection-type television receivers uses a plurality of liquid crystal panels capable of modulating light colors. Such a receiver is referred to at pages 415 to 418 in "SID 91 DIGEST."
SUMMARY OF THE INVENTION
Various aspects of the invention are as follows:
Television receiving apparatus for receiving and displaying television signals distributed in a plurality of formats, said television apparatus comprising:
input means for receiving said television signal;
color error correction means coupled to said input means for correcting color reproduction errors associated with the received television signal and providing a corrected television signal;
display means coupled to said color error correction means for receiving said corrected television signal and displaying a television image in accordance with said corrected television signal, said display means having a reproduction chromaticity range sufficiently wide to include essentially all of the transmission chromaticity range in said received television signal; and control means coupled to said color error correction means for controlling the operation of said color error correction means in accordance with the format of said received television signal.
Television receiving apparatus for reproducing a colored image transmitted by a television signal in any one of a plurality of systems with differing transmission specifications, said apparatus comprising:
-lOa-input means for receiving a television signal;
detection means coupled to said input means for receiving said television signal and detecting which system of said plurality of systems is 5 used for said television signal and generating a control signal which indicates the system of said television signal;
color error correction means for correcting color reproduction errors associated with said received television signal in accordance with said control signal and providing a corrected television signal;
white color setting means for setting a display white color temperature in accordance with said control signal and the system of said television signal; and display means having a reproduction chromaticity range wider than the transmission chromaticity ranges of each of the systems of said plurality 15 of systems, said display means displaying a television image in accordance with said corrected television signal and said display white color temperature.
A method for reproducing a color image transmitted by a television signal in any one of a plurality of systems with differing transmission 20 specifications, said method comprising the steps of:
receiving said television signal and providing a received television signal;
detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of 25 said television signal;
correcting color reproduction errors associated with the received television signal in accordance with said control signal and providing a corrected television signal; and driving a display device having a reproduction chromaticity range set 30 sufficiently wide to include the transmission chromaticity ranges of said plurality systems in accordance with said corrected television signal and displaying said colored image.
By way of added explanation, in accordance with an aspect of this invention, a television apparatus is provided for displaying an image 35 transmitted in accordance with a plurality of different transmission specifications and formats. The apparatus includes a color correction device --lOb-for correcting color reproduction errors associated with the received television signal. The reproduction errors are due to differences in the primary color chromaticity values between the transmission side and the reception side of the television signal. The errors must be corrected in order to provide faithful reproduction of the color picture information contained in the television signal for display at the receiver.
A control device also is provided for controlling the operation of the error correction device in accordance with the particular specification and 5 format of the received signal. The corrected primary color information is provided to a display for display of the television image with full and accurate color reproduction. The displayed image has reproduction chromaticity ranges which are sufficiently broad to include essentially all of the transmission chromaticity ranges of the various transmission systems 10 such as NTSC, HDTV, SMPTE and the like.
It is therefore an object of an aspect of the present invention to provide a television apparatus by which the colors on the transmission side of the system can be faithfully reproduced even when receiving a television signal from multiple systems with differing transmission specifications and formats.
An object of an aspect of the present invention is to provide a display apparatus which can provide natural gradation rendering when using different television system specifications and formats.
The above and other objects of the present invention will 2 1 ~ 3 become obvious upon an understancling of tha illustrative embodiments described below. Various advantage~ which are not referred to herein will also occur to those skilled in the art upon employment of the pr~sent invention in practice.
BRI~ D~8CRI~ION OF T~ DRAW~NG8 Figure 1 is a CIE chromaticity diagram howing the three primary color chromaticities o~ an NTSC system, a CRT phosphor display screen and an LCD display screen.
Figure 2 is a W chromaticity diagram showing eolor reproduc-tion errors.
Figure 3 is a block diagram illustrating a linear matrix circuit which corrects color reproduction errors.
Figures 4 and 5 are CIE chromaticity diagrams showing the three primary color chromaticities of an HDTV system and an SMPTE
system, respectively.
Figure 6 i~ a graph showing the gam~a curves of an NTSC and SMPTE system.
Figure 7 is a schematic block diagram showing a projection-type color television receiver to which an ~ hg~i ~nt of the present invention is applied.
Figure 8 i~ a graph showing the light emission distribution -~
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2110~3 characteristics of a metal halide lamp.
Figure 9 is a graph showing the integrated transmissivity characteristics of dichroic mirrors.
Figure 10 is a graph showing the light output characteristics of dichroic mirrors.
Figure 11 is a CIE chromaticity diagram showing the three primary color chromaticities of a television receiver in accordance with one ~ ho~i ?nt of the present invention.
Figure 12 is a block diagram showing the drive circuitry used for driving the liquid crystal panels shown in Figure 7 according to one embcdiment of the present invention.
Figure 13 is a block diagram showing the circuitry which generates control signals in accordance with the present invention.
Figure 14 is an illustration of a display screen showing a letter-box display.
Figure 15 i5 a block diagram showing a linear matrix circuit used for another A~ho~iment of the pre~ent invention.
DE~T~,R~ DE~C~IPTION OF T~ PREFERR~D EW~ODIMEN~
Representative ~ ho~i ents of the present invention will now be explained with reference to the accompanying drawings.
Figure 7 is a line drawing illustrating a projection-type 21p 1~3 color television receiver to which an embodiment o~ the present invention can be applied. In this embodiment, the projection type television receiver shown in Figure 7 is capable of receiving and displaying television picture inPormation in both the NTSC and HDTV
formats.
The receiver of Figure 7 operat~s in the following manner. A
white lamp 31 emits a high intenRity white light. A metal halide lamp which has superior color rendering can be used ~or white lamp 31. A reflector 32 is provided on the periphery o~ white lamp 31 and is the ~ocal point of the white light. The reflecting surface of reflector 32 is formed in the shape of a paraboloid so that the light from white lamp 31 is re~lected and directed in a parallel beam in a direction perpendicular to the reflecting surface of reflector 32.
~ W -IR filter 33 is po~itioned :Ln ~ront of white lamp 31.
This filter eliminates unwanted light from the beam re~lected from reflector 32. The reflQcted beam which p~ssPs through filter 33 is incident upon dichroic mirror 34. Dichroic mirror 34 reflects, or ~ilters out, blue light while passing other colors of light.
A mirror 35 is positioned on the beam axis of the blue light re~lected from dichroic mirror 34 and in turn reflects this light .. . . .
.. ... . . .
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210~3 to blue light liquid crystal panel 36 which is positioned on the beam axis of the light reflected from mirror 35. A dichroic mi.rror 37 is positioned on the beam axis of the light which pa~sed through dichroic mirror 34, and it reflects or filters out, red light while passing green light to green light liquid crystal panel 38. The red light reflected by dichroic mirror 37 is incident upon a liquid crystal panel 40. Thus the three liquid crystal panels 40, 38 and 36 recei~e an R signal, a G signal and a B signal, respectively, via terminals 43, 44 and 45 from a drive circuit which will be discussed below. At the same time, liquid crystal panels 40, 38 and 34 are supplied with, and driven by, sc~nning signals from a drive circuit so that each colored beam is modulated and respectively emitted a~ an R imag~ beam, a G imaqe bea~ and a B
image beam from their emission ~urfaces.
A synthesizing mirror 41 is positioned on both beam axis of the light emitted from liquid crystal panels 40 and 36. Mirror 41 optically synthesizes and transmits the B image beam and the R
image beam from liguid crystal panels 3S and 40. A mirror 39 reflects the G image beam from liquid crystal panel 38. This reflected beam is directed to another synthesizing mirror 42.
Synthesizing mirror 42 optically synthesizes the image beam from . : , .
.,. . : - -2104~3 synthesizing mirror 41 and the G image beam from mirror 39 and directs them to a projection lens 46. Projection lens 46 is designed so that the incident beam is magnified and projected onto a screen 47.
Figure 8 is a graph showing the typical light emission distribution characteristics for the metal halide lamp us~d for white lamp 31, where wavelength is plotted along the horizontal axis and relative luminous intensity i5 plotted along the vertical axis. As shown in Figure 8, a continuous spectrum of light i8 emitted from white lamp 31. This continuous spectrum o~ ligh~ is resolved by dichroic mirrors 34 and 37 in order to obtain the three primary color beams, blue, red and green.
Figure 9 is a graph showing the integrated transmissivity curves of dichroic mirrors 34 and 37, where wavelength is plotted along the horizontal axis and trAn~ ;ssivity is plotted along the vertical axis. In the graph, the dot-dash line (B~, the solid line ~R) and th~ h~ line (G) show that wavel~ngths in the vicinity of blue, red and gr~en light, respectively, can be obtained.
Figure 10 is a qraph showing the light output curves of dichroic mirrors 34 and 37, where wavelength is plotted along the horizontal axis and quantity of light emitted is plotted along the : , . .
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2~0~3 vertical axis.
The light from white lamp 31 is split into the three primary colors having the characteristics shown in Figure 10 by passing the light through dlchroic mirrors 34 and 37 as discussed above. When liquid crystal panel~ 36, 38 and 40 are in the transmission state, image beams with the same characteristics ~s shown in Figure 10 are emitted. Thus, display of the three primary color chromaticities are determined by the light-emitting characteristics of white lamp 31 and the transmissivity characteristics of the optical c-omponents of dichroic mirrors 34 and 37. Display of the three primary color chromaticities also vary due to the optical component characteristics of W-IR filter 33, pro~ection lens 46 and mirrors 35, 39, 41 and 42. However, variations due to these components are small and are not dominant factors.
Control of the display of the three primary color chromaticity values can be accomplished relatively easily by suitably setting the tr~n~ sivity characteristics of dichroic mirrors 34 and 37.
For example, when it is desired to project a color on the spectrum locus in a CIE chroma~ici~y diagram, a dichroic mirror having narrow band filter characteristics and which only transmits light of that wavelength is used. In this embodiment, the light-emitting ~ .
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' ' 210~4~3 characteristics of white lamp 31, and the transmissivity characteristicR of dichroic mirrors 34 and 37, are set for the reproduction range of the three primary color chromaticity values for both the NTSC and HDTV systems.
Figure ll is a CIE chromaticity diagram showing the chromaticity values for displaying the three primary color chromaticities which are established by settlng the optical system illustrated in Figure 7 so that the color reproduction range is set to the chromaticity range shown by the thick-line triallgle, i.e., the range which includes the NTSC and NDTV formatsO
Figure 12 i~ a block diagram showing the drive circuitry which upplies the R, G and B image signals to terminals 43, 44 and 45 in Figure 7. As shown in Figure 12, respective R, G and B original image coLor signals are supplied to input terminals 51, 52 and 53 and in turn, to linear matrix circuits 54 and 55. Matrix circuits 54 and 55 differ fro~ the matrix circuit in Figure 3 only with respect to th~ correc~ion matrix coefficients in coefficient circuits 8 to 16 and the characteristics of gamma addition cixcuits 20 to 22.: In other words, linear matrix circuit 54 sets the correction m trix coefficients so that the three display primary color chromaticities agree with the three transmission primary .
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color chromaticities of an NTSC system. Linear matrix circuit 55 also sets the correction matrix coe~icients so that the three display primary color chromaticities agree with the three transmission primary color chromaticities of the HDTV system.
A switching circuit 56 is controlled by a control signal from terminal 58. Circuit 56 selects either the R, G and B signals from linear matrix circuit 54, or the R, G and ~ signals from linear matrix circuit 55, and outputs them to a video signal processing circuit 57. The control signal supplied to terminal 58 indicates whether the rece:ived signal is an NTSC or HDTV ~ormat signal. When receiving an NTSC format signal, swil:ching circuit 56 selects linear matrix circuit 54 and when receiving an HDTV format signal, switching circuit 56 selects linear matrix clrcuit 55.
Video signal processing circuit 57 performs contrast adjustment, brightness adjustment and picture quality correction and outputs process~d signals to gamma correction circuit 59.
Transmission gamma is originally added to the television ignal on the transmission side by taking in account the vol~age/brightness characteristics of the CRT. Therefore, gamma correction circuit 59 performs gamma corre~tion which takes into consideration the reverse correction of transmission gamma and the transmissivity .: . , , ~ , . . .
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,' ' ' ' . ' ' " ' 2104~3 characteristics of liquid crystal panel5 36, 38 and 40.
The gamma addition circuits of linear matrix circuits 54 and 55 of the present embodiment are designed to add a transmission gamma which is the specification value o~ one of the broadcast systems. The transmission gamma which conforms to the HDTV
specification and format is added in the present embodiment independently of the format of the received signal. 3y this process, ~luctuation~ in the graduation rendering of the black side due to the system can be prevented.
Gamma correction circuit 59 may be omitted by correcting the transmissivity characteristics of the liquid crystal panels using the gamma addition circuits in linear ]natrix circuits 54 and 55.
In addition, the gamma addition circuits may be omitted by adding tr~n~ ;~sion gamma using gamma correction circuit 59 for correcting ~he transmissivity characteristics of the liquid Grystal panels.
The output signal from gamma correction circuit 59 is supplied to drive adjustment circuit 60. The output signal from drive ad~ustment circuit 60 is supplied to cut-o~f ad~ustment circuit 61.
Circuits 60 ~nd 61 perform white balance adjustment of the black and white sides of the displayed image. Drive adjustment circuit 60 is designed to alter the display white color temperature in ; ., , . ,', ~ ', ' , .............. ' ' ' ,:':' , , . ' ' ' ' ~ ' ' , "' ~ '; " .': ' ' " " ' 2 ~ 3 accordance with the control signal received from terminal 58. For instance, drive adjustment circuit 60 alters the ratios between the R, G and B signals by fixing the gain of the G signal and adjusting the gains of the B and R signals. By this process, drive adjustment circuit 60 controls the display white color temperature.
In this embodiment, drive adjustment circuit 60 ~ets the white color temperature to C light (6774 K) when it is indicated by the control signal that an NTSC broadcast is being received. Drive adjustment circuit 60 sets the white color temperature to D65 light (6504 K) when it is indicated that an HDTV broadcast is being received.
rhe output ~ignal from cut-off adjustment circuit 61 is supplied to polarity reversal circuit 62. circuit 62 converts the R, G and B signals to alternating signals in order to drive the liquid crystal p~n~l~. The output signals from polarity reversal circuit 62 are -~upplied to te~ in~ls 43, 44 and 45 via buffer circuit 63 and then to the liquid crystal panels 40, 38 and 36, shown in Figure 7, as the R, G and B signals for modulating the colored beams, respectively.
Figure 13 is a block diagram showing the circuitry which ~ . "~ , . . - , . .
.. . . .
.
- :
4~3 generat~s the control signal supplied to terminal 58 in Figure 12.
since the aspect ratio of the display in an HDTV system is 16:9, the entire HDTV image cannot be displayed on the full screen area of an NTSC system display unit without distortion due its much small aspect ration of 3:4. For this reason, a letter-box display is quite often adopted in this situation which renders the top and bottom of the screen non-graphic or unusable for the display of picture information.
Such a letter-box display is illustrated in Figure 14. The image of the HD~V system is displayed in a center section 64a of screen 64. The non-graphic section 64b is monitored in order to detect whether a received television signal i5 in an NTSC format or an HDTV format. The image signal on input terminal 65 is supplied to non-graphic section monitor circuit 66. A microcomputer unit 67 supplies a search signal to monitor circuit 66 during a specified sc~nn; ng line period before and after each vertical blanking period. Monitor circuit 66 monitors whether there is an imaye signal during the time of the search signal. As a result, microcomputer unit 67 outputs a control signal to ter~inal 58 which indicates an NTSC system when an image signal exists during the ti~ o~ the search signal and indicates an HDTV system when no ,,~, - . . . . .
,: ~ . . ~ . , ' -:' . ' . . , : ~
., - ' ' , . . .
-23~10~'~43 image signal exist during the time of the sea.rch signal.
The operation of this embodiment will now be explained. The chromaticity ranges of the color beams which are incident upon liquid crystal panels 36, 38 and 40 in Figure 7 are those shown by the thick line in Figure 11 by suitably setting the characteristics of white lamp 31 and dichroic mirrors 34 and 37. Thus, every color of the transmission specification of the NTSC and HDTV systems can ~aithfully be reproduced. The R, G and ~ signals are supplied to liquid crystal panels 40, 38 and 36, respectively. By controlling the quantity of incident beam transmission based on these signals, R, G and B image beams are emitted ~rom the liquid crystal panels.
In the case where an NTSC telev:ision signal is received, switching circuit 56 in Figure 12 sellects the output of linear matrix clrcuit 54. .Linear matrix circuLt 54 corrects the R, G and B original signals by using the correction matrix coefficients according to the NTSC system. In addition, drive adjustment circuit 60 sets the display white color temperature to C light. By using this process, the R, G and B signals are corrected ~or color reproduction errors and are supplied to liquid crystal panels 40, 38 and 36.
When an HDTV television signal is rec~ived, switching circuit :
' ' ~ ' ' ' ''' .
. . . .
;: :: ,. .
, -24210~3 56 selects the output of linear matrix circuit 55. Tha R, G and B
signals are corrected by using the correction matrix coef~icients according to the HDTV system and are supplied to video signal processing circuit 57. Drive adjustment circuit 60 also sets the display whita color temperature to D6s light. As a result, when an image signal o~ either an NTSC or an HDTV system is received, color reproduction errors are accurately correctad by correcting the display..primary color chromaticities as shown by the arrow in Figure 11 and also by changing the display white color temperature.
Moreover, and as described above, since the chromaticity ranges of the color beams incident upon liquid crystal panels 36, 38 and 40 are wider than that o~ either system specification, the color of the transmission side of the signal can be correctly reproduced.
In addition, the gamma addition circuits o~ linear matrix circuits 54 and 55 add tr~n! ission gamma for the appropriate system.
Therefore, regardless of the tr~n! ission system used, the same gradation rendering can be obtained and the unnaturalness o~ the block side gradation rend~ring can be improved.
In accordance with this embodiment, a projection-type television system is used and its reproduction chromaticity ranges ' ' . ' ' '' ' ~ ' : :
~25~10~3 are made much broader than those of the transmission specification and format of either an NTSC or an HDTV system by suitably settinq its optical system. Color reproduction errors are corrected by using the appropriate correction matrix coefficients and display white color temperature according to the system used by the received television signal. As a result, the transmi~ted colors can be correctly reproduced on the receiver display.
In the case of converting a HDTV, SMPTE, PAL or SECAM
broadcast signal to an NTSC signal and displaying the converted signal on an NTSC receiver, good color reproduction can be obtained by correcting the color reproduction errors in the same manner as described above. In other words, even with a standard NTSC
televi~ion receiver, color reproduction errors due to differences in the primary color chromaticities of the original slgnal can be corrected. In addition, the present invention is able to correct di~ference~ in the gamma curves of the transmitted signal. Thus, unnaturalnes~ of the block side gradation rendering can be solved.
Figure 15 is a block diagram showing a linear matrix circuit u~ed for another ~ ~o~iment of this invention. In this linear matrix circuit, the gamma cancellation and gamma addition circuits are common for NTSC and HDTV systems. This embodiment differs from ' ': , ~:
':
~26- 210~3 the embodiment illustrated in Figure 12 with respect to linear matrix circuit 71 which is used in place of linear matrix circuits 54 and 55 and switching circuit 56. The G, B and R original signals, which are supplied via input terminals 51, 52 and 53, are supplied to respective gamma cancellation circuits 72, 73 and 74.
Gamma cancellation circuits 72, 73 and 74 cancel out the transmission gamma and supply the output signals to coef~icient circuit~ 8 to 16 and 78 to &6 of matrix circuit 75. Coefficient circuits 8 to 16 multiply the supplied R, G and B signals by correction matrix coefficients which correspond to the NTSC system.
Coefficient circuits 78 to 86 multiply the supplied R, G and B
signals by correction matrix coefficients which correspond to the HD~V system. The control signal indicating the identity of the received.broadcast system is supplied to switching circuit 87 from teL 1 nAI 58. During an NTSC bro~c~t, switching circuit 87 selects th~ ou~uL signals of coefficient circuits 8 to 16 and supplies these signal~ to adders 17 to 19.
During an HDTV broadcast, switching circuit 87 selects the output si~nals of coefficient circuits 78 to ~6 and supplies these signals to adders i7 to 19. Adders 17 to 19 add the three supplied signals of each color and provide the signals to respectiva gamma ,. ~ . ! ' ~ : ' ' . ' , ' . . :
:' :
. : ' . ' . : : ' .' ~ .' . ' ~ ' ' ~ ' ' ' ' ' '' . ., ' ' ~ ~:
-27- 2 ~ 3 addition circuits 88, 89 and 90. Gamma addition circuits 88, 89 and so add transmission gamma to the respective color signals.
In this embodiment, correction of the original signal is switched according to the particular broadcast sy~tem (NTSC or HDTV) the same as described above with respect to the first embodiment of this invention. Also in this ambodiment, the size of the circuitry can be reduced by making the gamma cancellation and gamma addition circuits common for both the NTSC and HDTV systems.
In the above embodiments, the linear matrix circuits are positioned at the initial stage in the drive circuit as shown in Figure 12. However, these circuits may be positioned at a later stage as well. Note tha~ the display p:rimary color chromaticities are set by the white lamp and the optical system so that they include the transmission primary color chromaticities of multiple systems, such as NTSC and HDTV. However, the chroma~icity ranges o~ an NTSC system clearly are distinguished from those o~ other systams but include the other systems as shown in Figures 4 and 5.
Note, however, that the chromaticity of blue has little influence on visual ef~ects in comparison with other colors as the differences between the chromaticity of blu~ in the NTSC and HDTV
systems is not ~reat. Thus, even when the display primary color ,, .,: ~ . ~
-2~ 21~ 3 chromaticitles are set to NTSC values in this embodiment, nearly the same visual effect can be achieved as in the previously discussed embodiments. In this case, the linear matrix circuit for the NTSC system can be omitted, thus reducing the sizé and cost of the circuitry.
As descrLbed above, the present invention provides a display apparatus in which the transmitted colors can be faithfully reproduced, even when receiving television signals from multiple systems with differing transmission specifications and forma1ts.
The present invention also includes a display which can provide natural gradation rendering for the various transmission systems.
While the present invention has been illustrated and described in detail in the drawings and fore~oi,ng description, it will be recognized that changes and modificatiLons can and will occur to those skilled in the art. It is there~ore intended by the app~ing claims, to cover any such changes and modificaltions as fall within the true spirit and scope vf the invsntion.
: ~ ' ., ' :
- ~ .
'
COLOR TE~E~ O~ 8I~ Xa~I~ D~BR~N~ FORM~8 D OF T~ INV~N~I~N
The present invention generally relates to the color television field, and more particularly, is directed to a color television receiver which is capable of receiving and displaying color televi~ion ~ignals broadca~t with different transmission specification~ and formats. The receiver pe~its accurate reproduction and display of the color picture information contained in the received television signal without regard to its transmission speci~ication or ~ormat.
r -~ D 0~ ~E T~V~N~O~
In ~he NTSC teleuision signal system, which i8 the system presently in use in the United States ,and in many ok~er countries, the tr~n~ 3ion specifications and format wer~ esta~lished in order t~ maxi~ize the amount of red ~R), green (G) and blue (B) primary col~r in~or~ation which can be transmitted in the tel~vision signal. Thus, the NTSC specifications and format provide wide chromaticity ranges in order to insure transmission of .
. , .
, .: , , ~ .
~ : ~ . - .
~ .
' ~ ' .:: ' '' ~
full color content for the television image.
Television rec~ivers known in the prior art reproduce the color image con~ained in the television signal by adding and mixing the red, green, and blue primary color information extracted ~rom the television signal. However, the chrom~ticity ranges of a typical television receiver is narrower than the chromaticity ranges present in the received television signal. Thu~, full and faithful reproduction of the ~olor picture information contained in the television signal is not possible in televi ion receivers known in the prior art.
Figure 1 is a CIE (Commission International de Enluminure) chromaticity diagram illustrating the red, green and blue primary color chromaticity values for the NTSC sy~tem, the phosphor in a cathode ray tube (CRT) used in the typical television receiver and the color filter in a liquid crys~al display device (LCD), also now commonly used in small portable television receivers and large projection-type television displays. The NTSC chromaticity values are represented by the ~Ache~ line, the CRT chromaticity values are represented by th dot-dash line and the LCD values are represented ~y the solid line. The chromaticity values charted in Flgure 1 are set forth below in table form: .
, .. ~ .. .
. . ~ , " ~".
2~0~3 N~SC CR~' LCD
X Y X ~ X Y
R: 0.670 0.330 0~657 0.338 0.613 0.334 G: 00210 0.710 0.2~7 0.609 0.233 0.627 B: 0.140 0.080 0.148 0.054 0.140 0.079 The outer bold line in Figure 1, and associated numbers at the indicated points on the line, illustrate the spectrum locus and wave-lenqths (nm). In the NTSC system here, C light having a color temperature of 67~4 K is used as a referenc2 white light W with the following chromaticity:
W : X = 0.3101, Y = 0.3163 In the NTSC system, if the chromaticity values ~or the three primary color~ for the display ~CRT or LICD) in the receiver are set to the s~me as the NTSC values, the co.lor picture information in the tran3mitted television signal can be ~aithfully reproduced on the receiver display by setting the reierence white light to the c~romaticity of C light. Howev~r, a color television receiver must also b~ capable of receiving and displaying black and white television signals. Therefore, in order to achieve the requisite compatibility with black and white television broadcasts, a white color light with higher chromaticity values than C light must be x,. ~
, i : ~ ' ' ~ , ~ .......... . .
;
' . ' : : ~
2104~3 used as the reference.
In addition, the chromaticity values for the primary colors for a television receiver depends on the phosphor chro~aticities oP
the CRT or LCD which, as described above and shown in Figure 1, are different than the chromaticity values for the primary colors for the NTSC system. Therefore, if corrections are not made ~or the differences between the NTSC and receiver chro~aticity values, color errors will result and the color picture information contained in the television signal will not be faith~ully reproduced on the display in the receiver.
Moreover, and as also discussed above, the chromaticity ranges of the CRT and LCD are narrower than the NTSC chromaticity ranges.
Thus, the color reproduction range of the television receiver i5 not brvad enough to reproduce all o~ the color information contained in the ;nc ing television signal~ The~efore, even when the appropriate color corrections are made with respect to differencs~ in the NTSC and display chromaticity ~alues, the receiver is still not capable of faithful reproduction of every color received in the inc. ;ng television signal.
The types of color reprcduction errors discus~ed above are also referenced on page 959 in the book entitled "The New Color -... : :: ... . . ... - :
.. .~ . . . .
2 1 ~ 3 Science Handbook" which was published in Japan.
Figure 2 i~ a UV chromaticity diagram showing the color reproduction errors described above and referenced in the above mentioned handbook. The solid line triangle in Figure 2 indicate~
the chromaticity range for the primary colors of the NTSC system on the transmis~ion side of the television signal. The dashed line triangle illustrates the chromaticity range of the primary coiors of the CRT phosphor at the receiver. Note that while the NTSC a~d CRT ranges greatly overlap, the NTSC range is slightly larger and each of its values are shifted from the corresponding values in the CRT range. The graph in Figure 2 is obtained by calculating the color reproduction error based on the differences between the NTSC
ancl CRT chromaticity ranges. An example of some of the NTSC
chromati~ity values are shown by the dots in Figure 2. In order to correct color reproduction errors in the display, these values must be shifted in order to bring them into a corresponding point in the CRT chromaticity range as indicated by the arrows in Figure 2.
In CRT television receivers and color cameras, linear matrix circuits are used to correct color reproduction errors. Figure 3 is a block diagram showing a linear matrix oircuit which corrects such color reproduction errors. The G (green), B (blue) and R
.. ,.,. - ,~ -, : .
. ~
(red) primary color signals are supplied to input terminals 1, 2 and 3, respectively, and to gamma cancellation circuits 4, 5 and 6 so that transmission gamma is cancelled by removing the ga~ma correction which was added to the signal on the image transmission side.
The output signals ~rom gamma canc~llation circuits 4, 5 and 6 are supplied to matrix circuit 7 which is formed of coe~ficient circuits 8 to 16 and adders 17 to 1~. Matrix circuit 7 multiplies the supplied R, G and B signals by respective corre~tion matrix coefficients and then adds them together. Coefficient circuits 8 to 16 can be formed o~ simple circuits using resister~ as is known in the art. Gamma addition circuit:s 20, 21 and 22 add the transmission gamma to the respective corrected R, G and B color signals and outputs them via terminal~s 23, 24 and 25 as primary color signals Rl, Gl, and Bl. In this way, color reproduction errors are r~ :ved and approximatQly the same colors as in the transmitted image can bs re~Lo~uced at the receiver. However, the correction is possible only for colors in the region in which the solid line triangle and the ~he~ line triangle in Figur~ 2 overlap each other.
,~.. ... - . , - , ~ -. . ;
: . .:
2 ~ 4 3 Recently, there have been test broadcasts of a high definition television (~DTV) signal format which is capable of displaying high quality television images. Taking into account the popularity of the existing NTSC television system, and the large installed base of such equipment, television receivers which are capable of receiving images in both the NTSC and HD~Y system formats are being made commercially available. ~owever, the transmission specific~tions of an HDTV system are different from those o~ an NTSC system. In the HDTV transmission specification and format, th~ R, G and B primary color chromaticîties are as follows:
R: X - 0.640, Y = 0.330 G: X = 0.300, Y - 0.600 13: X = 0.150, Y = 0.0~) Also in the HDTV specification, D~ lis~ht is used as a reference white color and its chromaticity W Ls as follows:
~ : X = 0.3127, Y = 0.3290 Figur~ 4 is a ClE chromaticity diagram showing the NTSC
specification values and the HDTY specification vales of thP
respective R, G and B primary color chromaticities. As Figure 4 indicates, the chromaticity value ~or G in the NTSC syst~m is .j, . ~ - .
:.
.
'' ': ~
-~4~43 greatly dif~erent than the chromatic:ity value for G in t~e HDTV
system. Note, however, that the chromaticity value for G in the HD~V system is comparatively close to the chromaticity value for G
in CRT and LCD displays (see Figure 1). There~ore, in a television receiver which uses a C~T or LCD, there is comparatively little color reproduction error when receiving and displaying a HDTV
broadcast. There is, however, a likelihood of large color reproduction errors when receiving an NTSC broadcast as is apparent from Figure 1.
When correcting color reproduction errors for one system in a television receiver which is capable of receiving multiple system formats ~such NTSC and HD~V) in which the three primary color chromaticity values differ from one system to the other, color reproduction errors in the other systems cannot be corrected~
Television P~OYLamS produced by the HDTV system and commercial feature ~ilms are sometimes bro~r~cted using the NTSC system.
Faature ~ usually are produced in accordance with specifications established by the Society o~ ~otion Pictura and Television Engineers (SMPTE~. The HDTV system also i5 set to conform to SMPTE specifications.
Eigure 5 is a CIE chromaticity diagram showing the ,' :
', . ' ''''~;' :' ~ ' ' 2 1 ~
.9_ transmission primary color chromaticity values for both the SMPTE
and NTSC systems. As is apparent from Figures 4 and 5, the transmission primary color chromaticity values for the HDTV system approximately coincides with those of the SMPTE system. Also, the PAL and SECAM television signal transmission systems are nearly standardized to the EBU specifications~ The transmission primary color chromaticity values for thase systems also approximately coincide with those of the HDTV system There is presently known in the art an HDTV to NTSC system converter which enables reception of HDTV broadcasts on a standard NTSC system television receiver. With such a converter, or other equipment having similar functions as that of the converter, it is possible to also convert other signal f'ormats, such as SMPTE, PAL
and SECAM to NTSC for display on a standard NTSC receiver. However, the transmission gamma of the NTSC syste~ dif~ers from the transmission ga~ma of any one of the other systems.
Figure 6 is ~ ~raph illustra~ing transmission gamma. The solid line shows the gamma curve of the SMPTE system and the dashed line shows the gamma curve of the NTSC system (~ = 0~45~ s shown in Figure 6, the black side values in particular differ between the NTSC and the SMPTE systems. Due to the difference between the -. ~ . : .
.
gamma curves, the rendering of the black gradations sometimes is unnatural depending on the signal source of the broadcast program. For instance, even within the same broadcast program, the gradation rendering differs according to the difference in the signal source, namely in accordance with 5 the specification under which the program was produced.
In addition to television receivers which use a CRT or liquid crystal display, recently projection-type color television receivers have been developed in order to provide large-screen viewing. Projection-type television receivers uses a plurality of liquid crystal panels capable of modulating light colors. Such a receiver is referred to at pages 415 to 418 in "SID 91 DIGEST."
SUMMARY OF THE INVENTION
Various aspects of the invention are as follows:
Television receiving apparatus for receiving and displaying television signals distributed in a plurality of formats, said television apparatus comprising:
input means for receiving said television signal;
color error correction means coupled to said input means for correcting color reproduction errors associated with the received television signal and providing a corrected television signal;
display means coupled to said color error correction means for receiving said corrected television signal and displaying a television image in accordance with said corrected television signal, said display means having a reproduction chromaticity range sufficiently wide to include essentially all of the transmission chromaticity range in said received television signal; and control means coupled to said color error correction means for controlling the operation of said color error correction means in accordance with the format of said received television signal.
Television receiving apparatus for reproducing a colored image transmitted by a television signal in any one of a plurality of systems with differing transmission specifications, said apparatus comprising:
-lOa-input means for receiving a television signal;
detection means coupled to said input means for receiving said television signal and detecting which system of said plurality of systems is 5 used for said television signal and generating a control signal which indicates the system of said television signal;
color error correction means for correcting color reproduction errors associated with said received television signal in accordance with said control signal and providing a corrected television signal;
white color setting means for setting a display white color temperature in accordance with said control signal and the system of said television signal; and display means having a reproduction chromaticity range wider than the transmission chromaticity ranges of each of the systems of said plurality 15 of systems, said display means displaying a television image in accordance with said corrected television signal and said display white color temperature.
A method for reproducing a color image transmitted by a television signal in any one of a plurality of systems with differing transmission 20 specifications, said method comprising the steps of:
receiving said television signal and providing a received television signal;
detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of 25 said television signal;
correcting color reproduction errors associated with the received television signal in accordance with said control signal and providing a corrected television signal; and driving a display device having a reproduction chromaticity range set 30 sufficiently wide to include the transmission chromaticity ranges of said plurality systems in accordance with said corrected television signal and displaying said colored image.
By way of added explanation, in accordance with an aspect of this invention, a television apparatus is provided for displaying an image 35 transmitted in accordance with a plurality of different transmission specifications and formats. The apparatus includes a color correction device --lOb-for correcting color reproduction errors associated with the received television signal. The reproduction errors are due to differences in the primary color chromaticity values between the transmission side and the reception side of the television signal. The errors must be corrected in order to provide faithful reproduction of the color picture information contained in the television signal for display at the receiver.
A control device also is provided for controlling the operation of the error correction device in accordance with the particular specification and 5 format of the received signal. The corrected primary color information is provided to a display for display of the television image with full and accurate color reproduction. The displayed image has reproduction chromaticity ranges which are sufficiently broad to include essentially all of the transmission chromaticity ranges of the various transmission systems 10 such as NTSC, HDTV, SMPTE and the like.
It is therefore an object of an aspect of the present invention to provide a television apparatus by which the colors on the transmission side of the system can be faithfully reproduced even when receiving a television signal from multiple systems with differing transmission specifications and formats.
An object of an aspect of the present invention is to provide a display apparatus which can provide natural gradation rendering when using different television system specifications and formats.
The above and other objects of the present invention will 2 1 ~ 3 become obvious upon an understancling of tha illustrative embodiments described below. Various advantage~ which are not referred to herein will also occur to those skilled in the art upon employment of the pr~sent invention in practice.
BRI~ D~8CRI~ION OF T~ DRAW~NG8 Figure 1 is a CIE chromaticity diagram howing the three primary color chromaticities o~ an NTSC system, a CRT phosphor display screen and an LCD display screen.
Figure 2 is a W chromaticity diagram showing eolor reproduc-tion errors.
Figure 3 is a block diagram illustrating a linear matrix circuit which corrects color reproduction errors.
Figures 4 and 5 are CIE chromaticity diagrams showing the three primary color chromaticities of an HDTV system and an SMPTE
system, respectively.
Figure 6 i~ a graph showing the gam~a curves of an NTSC and SMPTE system.
Figure 7 is a schematic block diagram showing a projection-type color television receiver to which an ~ hg~i ~nt of the present invention is applied.
Figure 8 i~ a graph showing the light emission distribution -~
~ .
! :
,, " ' ' ~
2110~3 characteristics of a metal halide lamp.
Figure 9 is a graph showing the integrated transmissivity characteristics of dichroic mirrors.
Figure 10 is a graph showing the light output characteristics of dichroic mirrors.
Figure 11 is a CIE chromaticity diagram showing the three primary color chromaticities of a television receiver in accordance with one ~ ho~i ?nt of the present invention.
Figure 12 is a block diagram showing the drive circuitry used for driving the liquid crystal panels shown in Figure 7 according to one embcdiment of the present invention.
Figure 13 is a block diagram showing the circuitry which generates control signals in accordance with the present invention.
Figure 14 is an illustration of a display screen showing a letter-box display.
Figure 15 i5 a block diagram showing a linear matrix circuit used for another A~ho~iment of the pre~ent invention.
DE~T~,R~ DE~C~IPTION OF T~ PREFERR~D EW~ODIMEN~
Representative ~ ho~i ents of the present invention will now be explained with reference to the accompanying drawings.
Figure 7 is a line drawing illustrating a projection-type 21p 1~3 color television receiver to which an embodiment o~ the present invention can be applied. In this embodiment, the projection type television receiver shown in Figure 7 is capable of receiving and displaying television picture inPormation in both the NTSC and HDTV
formats.
The receiver of Figure 7 operat~s in the following manner. A
white lamp 31 emits a high intenRity white light. A metal halide lamp which has superior color rendering can be used ~or white lamp 31. A reflector 32 is provided on the periphery o~ white lamp 31 and is the ~ocal point of the white light. The reflecting surface of reflector 32 is formed in the shape of a paraboloid so that the light from white lamp 31 is re~lected and directed in a parallel beam in a direction perpendicular to the reflecting surface of reflector 32.
~ W -IR filter 33 is po~itioned :Ln ~ront of white lamp 31.
This filter eliminates unwanted light from the beam re~lected from reflector 32. The reflQcted beam which p~ssPs through filter 33 is incident upon dichroic mirror 34. Dichroic mirror 34 reflects, or ~ilters out, blue light while passing other colors of light.
A mirror 35 is positioned on the beam axis of the blue light re~lected from dichroic mirror 34 and in turn reflects this light .. . . .
.. ... . . .
. .
:
210~3 to blue light liquid crystal panel 36 which is positioned on the beam axis of the light reflected from mirror 35. A dichroic mi.rror 37 is positioned on the beam axis of the light which pa~sed through dichroic mirror 34, and it reflects or filters out, red light while passing green light to green light liquid crystal panel 38. The red light reflected by dichroic mirror 37 is incident upon a liquid crystal panel 40. Thus the three liquid crystal panels 40, 38 and 36 recei~e an R signal, a G signal and a B signal, respectively, via terminals 43, 44 and 45 from a drive circuit which will be discussed below. At the same time, liquid crystal panels 40, 38 and 34 are supplied with, and driven by, sc~nning signals from a drive circuit so that each colored beam is modulated and respectively emitted a~ an R imag~ beam, a G imaqe bea~ and a B
image beam from their emission ~urfaces.
A synthesizing mirror 41 is positioned on both beam axis of the light emitted from liquid crystal panels 40 and 36. Mirror 41 optically synthesizes and transmits the B image beam and the R
image beam from liguid crystal panels 3S and 40. A mirror 39 reflects the G image beam from liquid crystal panel 38. This reflected beam is directed to another synthesizing mirror 42.
Synthesizing mirror 42 optically synthesizes the image beam from . : , .
.,. . : - -2104~3 synthesizing mirror 41 and the G image beam from mirror 39 and directs them to a projection lens 46. Projection lens 46 is designed so that the incident beam is magnified and projected onto a screen 47.
Figure 8 is a graph showing the typical light emission distribution characteristics for the metal halide lamp us~d for white lamp 31, where wavelength is plotted along the horizontal axis and relative luminous intensity i5 plotted along the vertical axis. As shown in Figure 8, a continuous spectrum of light i8 emitted from white lamp 31. This continuous spectrum o~ ligh~ is resolved by dichroic mirrors 34 and 37 in order to obtain the three primary color beams, blue, red and green.
Figure 9 is a graph showing the integrated transmissivity curves of dichroic mirrors 34 and 37, where wavelength is plotted along the horizontal axis and trAn~ ;ssivity is plotted along the vertical axis. In the graph, the dot-dash line (B~, the solid line ~R) and th~ h~ line (G) show that wavel~ngths in the vicinity of blue, red and gr~en light, respectively, can be obtained.
Figure 10 is a qraph showing the light output curves of dichroic mirrors 34 and 37, where wavelength is plotted along the horizontal axis and quantity of light emitted is plotted along the : , . .
:: : :, ' ~
. ~ .
2~0~3 vertical axis.
The light from white lamp 31 is split into the three primary colors having the characteristics shown in Figure 10 by passing the light through dlchroic mirrors 34 and 37 as discussed above. When liquid crystal panel~ 36, 38 and 40 are in the transmission state, image beams with the same characteristics ~s shown in Figure 10 are emitted. Thus, display of the three primary color chromaticities are determined by the light-emitting characteristics of white lamp 31 and the transmissivity characteristics of the optical c-omponents of dichroic mirrors 34 and 37. Display of the three primary color chromaticities also vary due to the optical component characteristics of W-IR filter 33, pro~ection lens 46 and mirrors 35, 39, 41 and 42. However, variations due to these components are small and are not dominant factors.
Control of the display of the three primary color chromaticity values can be accomplished relatively easily by suitably setting the tr~n~ sivity characteristics of dichroic mirrors 34 and 37.
For example, when it is desired to project a color on the spectrum locus in a CIE chroma~ici~y diagram, a dichroic mirror having narrow band filter characteristics and which only transmits light of that wavelength is used. In this embodiment, the light-emitting ~ .
: .
' ' 210~4~3 characteristics of white lamp 31, and the transmissivity characteristicR of dichroic mirrors 34 and 37, are set for the reproduction range of the three primary color chromaticity values for both the NTSC and HDTV systems.
Figure ll is a CIE chromaticity diagram showing the chromaticity values for displaying the three primary color chromaticities which are established by settlng the optical system illustrated in Figure 7 so that the color reproduction range is set to the chromaticity range shown by the thick-line triallgle, i.e., the range which includes the NTSC and NDTV formatsO
Figure 12 i~ a block diagram showing the drive circuitry which upplies the R, G and B image signals to terminals 43, 44 and 45 in Figure 7. As shown in Figure 12, respective R, G and B original image coLor signals are supplied to input terminals 51, 52 and 53 and in turn, to linear matrix circuits 54 and 55. Matrix circuits 54 and 55 differ fro~ the matrix circuit in Figure 3 only with respect to th~ correc~ion matrix coefficients in coefficient circuits 8 to 16 and the characteristics of gamma addition cixcuits 20 to 22.: In other words, linear matrix circuit 54 sets the correction m trix coefficients so that the three display primary color chromaticities agree with the three transmission primary .
.- ' . ' ' 2104~
color chromaticities of an NTSC system. Linear matrix circuit 55 also sets the correction matrix coe~icients so that the three display primary color chromaticities agree with the three transmission primary color chromaticities of the HDTV system.
A switching circuit 56 is controlled by a control signal from terminal 58. Circuit 56 selects either the R, G and B signals from linear matrix circuit 54, or the R, G and ~ signals from linear matrix circuit 55, and outputs them to a video signal processing circuit 57. The control signal supplied to terminal 58 indicates whether the rece:ived signal is an NTSC or HDTV ~ormat signal. When receiving an NTSC format signal, swil:ching circuit 56 selects linear matrix circuit 54 and when receiving an HDTV format signal, switching circuit 56 selects linear matrix clrcuit 55.
Video signal processing circuit 57 performs contrast adjustment, brightness adjustment and picture quality correction and outputs process~d signals to gamma correction circuit 59.
Transmission gamma is originally added to the television ignal on the transmission side by taking in account the vol~age/brightness characteristics of the CRT. Therefore, gamma correction circuit 59 performs gamma corre~tion which takes into consideration the reverse correction of transmission gamma and the transmissivity .: . , , ~ , . . .
:. .-. .
.-.
.
,' ' ' ' . ' ' " ' 2104~3 characteristics of liquid crystal panel5 36, 38 and 40.
The gamma addition circuits of linear matrix circuits 54 and 55 of the present embodiment are designed to add a transmission gamma which is the specification value o~ one of the broadcast systems. The transmission gamma which conforms to the HDTV
specification and format is added in the present embodiment independently of the format of the received signal. 3y this process, ~luctuation~ in the graduation rendering of the black side due to the system can be prevented.
Gamma correction circuit 59 may be omitted by correcting the transmissivity characteristics of the liquid crystal panels using the gamma addition circuits in linear ]natrix circuits 54 and 55.
In addition, the gamma addition circuits may be omitted by adding tr~n~ ;~sion gamma using gamma correction circuit 59 for correcting ~he transmissivity characteristics of the liquid Grystal panels.
The output signal from gamma correction circuit 59 is supplied to drive adjustment circuit 60. The output signal from drive ad~ustment circuit 60 is supplied to cut-o~f ad~ustment circuit 61.
Circuits 60 ~nd 61 perform white balance adjustment of the black and white sides of the displayed image. Drive adjustment circuit 60 is designed to alter the display white color temperature in ; ., , . ,', ~ ', ' , .............. ' ' ' ,:':' , , . ' ' ' ' ~ ' ' , "' ~ '; " .': ' ' " " ' 2 ~ 3 accordance with the control signal received from terminal 58. For instance, drive adjustment circuit 60 alters the ratios between the R, G and B signals by fixing the gain of the G signal and adjusting the gains of the B and R signals. By this process, drive adjustment circuit 60 controls the display white color temperature.
In this embodiment, drive adjustment circuit 60 ~ets the white color temperature to C light (6774 K) when it is indicated by the control signal that an NTSC broadcast is being received. Drive adjustment circuit 60 sets the white color temperature to D65 light (6504 K) when it is indicated that an HDTV broadcast is being received.
rhe output ~ignal from cut-off adjustment circuit 61 is supplied to polarity reversal circuit 62. circuit 62 converts the R, G and B signals to alternating signals in order to drive the liquid crystal p~n~l~. The output signals from polarity reversal circuit 62 are -~upplied to te~ in~ls 43, 44 and 45 via buffer circuit 63 and then to the liquid crystal panels 40, 38 and 36, shown in Figure 7, as the R, G and B signals for modulating the colored beams, respectively.
Figure 13 is a block diagram showing the circuitry which ~ . "~ , . . - , . .
.. . . .
.
- :
4~3 generat~s the control signal supplied to terminal 58 in Figure 12.
since the aspect ratio of the display in an HDTV system is 16:9, the entire HDTV image cannot be displayed on the full screen area of an NTSC system display unit without distortion due its much small aspect ration of 3:4. For this reason, a letter-box display is quite often adopted in this situation which renders the top and bottom of the screen non-graphic or unusable for the display of picture information.
Such a letter-box display is illustrated in Figure 14. The image of the HD~V system is displayed in a center section 64a of screen 64. The non-graphic section 64b is monitored in order to detect whether a received television signal i5 in an NTSC format or an HDTV format. The image signal on input terminal 65 is supplied to non-graphic section monitor circuit 66. A microcomputer unit 67 supplies a search signal to monitor circuit 66 during a specified sc~nn; ng line period before and after each vertical blanking period. Monitor circuit 66 monitors whether there is an imaye signal during the time of the search signal. As a result, microcomputer unit 67 outputs a control signal to ter~inal 58 which indicates an NTSC system when an image signal exists during the ti~ o~ the search signal and indicates an HDTV system when no ,,~, - . . . . .
,: ~ . . ~ . , ' -:' . ' . . , : ~
., - ' ' , . . .
-23~10~'~43 image signal exist during the time of the sea.rch signal.
The operation of this embodiment will now be explained. The chromaticity ranges of the color beams which are incident upon liquid crystal panels 36, 38 and 40 in Figure 7 are those shown by the thick line in Figure 11 by suitably setting the characteristics of white lamp 31 and dichroic mirrors 34 and 37. Thus, every color of the transmission specification of the NTSC and HDTV systems can ~aithfully be reproduced. The R, G and ~ signals are supplied to liquid crystal panels 40, 38 and 36, respectively. By controlling the quantity of incident beam transmission based on these signals, R, G and B image beams are emitted ~rom the liquid crystal panels.
In the case where an NTSC telev:ision signal is received, switching circuit 56 in Figure 12 sellects the output of linear matrix clrcuit 54. .Linear matrix circuLt 54 corrects the R, G and B original signals by using the correction matrix coefficients according to the NTSC system. In addition, drive adjustment circuit 60 sets the display white color temperature to C light. By using this process, the R, G and B signals are corrected ~or color reproduction errors and are supplied to liquid crystal panels 40, 38 and 36.
When an HDTV television signal is rec~ived, switching circuit :
' ' ~ ' ' ' ''' .
. . . .
;: :: ,. .
, -24210~3 56 selects the output of linear matrix circuit 55. Tha R, G and B
signals are corrected by using the correction matrix coef~icients according to the HDTV system and are supplied to video signal processing circuit 57. Drive adjustment circuit 60 also sets the display whita color temperature to D6s light. As a result, when an image signal o~ either an NTSC or an HDTV system is received, color reproduction errors are accurately correctad by correcting the display..primary color chromaticities as shown by the arrow in Figure 11 and also by changing the display white color temperature.
Moreover, and as described above, since the chromaticity ranges of the color beams incident upon liquid crystal panels 36, 38 and 40 are wider than that o~ either system specification, the color of the transmission side of the signal can be correctly reproduced.
In addition, the gamma addition circuits o~ linear matrix circuits 54 and 55 add tr~n! ission gamma for the appropriate system.
Therefore, regardless of the tr~n! ission system used, the same gradation rendering can be obtained and the unnaturalness o~ the block side gradation rend~ring can be improved.
In accordance with this embodiment, a projection-type television system is used and its reproduction chromaticity ranges ' ' . ' ' '' ' ~ ' : :
~25~10~3 are made much broader than those of the transmission specification and format of either an NTSC or an HDTV system by suitably settinq its optical system. Color reproduction errors are corrected by using the appropriate correction matrix coefficients and display white color temperature according to the system used by the received television signal. As a result, the transmi~ted colors can be correctly reproduced on the receiver display.
In the case of converting a HDTV, SMPTE, PAL or SECAM
broadcast signal to an NTSC signal and displaying the converted signal on an NTSC receiver, good color reproduction can be obtained by correcting the color reproduction errors in the same manner as described above. In other words, even with a standard NTSC
televi~ion receiver, color reproduction errors due to differences in the primary color chromaticities of the original slgnal can be corrected. In addition, the present invention is able to correct di~ference~ in the gamma curves of the transmitted signal. Thus, unnaturalnes~ of the block side gradation rendering can be solved.
Figure 15 is a block diagram showing a linear matrix circuit u~ed for another ~ ~o~iment of this invention. In this linear matrix circuit, the gamma cancellation and gamma addition circuits are common for NTSC and HDTV systems. This embodiment differs from ' ': , ~:
':
~26- 210~3 the embodiment illustrated in Figure 12 with respect to linear matrix circuit 71 which is used in place of linear matrix circuits 54 and 55 and switching circuit 56. The G, B and R original signals, which are supplied via input terminals 51, 52 and 53, are supplied to respective gamma cancellation circuits 72, 73 and 74.
Gamma cancellation circuits 72, 73 and 74 cancel out the transmission gamma and supply the output signals to coef~icient circuit~ 8 to 16 and 78 to &6 of matrix circuit 75. Coefficient circuits 8 to 16 multiply the supplied R, G and B signals by correction matrix coefficients which correspond to the NTSC system.
Coefficient circuits 78 to 86 multiply the supplied R, G and B
signals by correction matrix coefficients which correspond to the HD~V system. The control signal indicating the identity of the received.broadcast system is supplied to switching circuit 87 from teL 1 nAI 58. During an NTSC bro~c~t, switching circuit 87 selects th~ ou~uL signals of coefficient circuits 8 to 16 and supplies these signal~ to adders 17 to 19.
During an HDTV broadcast, switching circuit 87 selects the output si~nals of coefficient circuits 78 to ~6 and supplies these signals to adders i7 to 19. Adders 17 to 19 add the three supplied signals of each color and provide the signals to respectiva gamma ,. ~ . ! ' ~ : ' ' . ' , ' . . :
:' :
. : ' . ' . : : ' .' ~ .' . ' ~ ' ' ~ ' ' ' ' ' '' . ., ' ' ~ ~:
-27- 2 ~ 3 addition circuits 88, 89 and 90. Gamma addition circuits 88, 89 and so add transmission gamma to the respective color signals.
In this embodiment, correction of the original signal is switched according to the particular broadcast sy~tem (NTSC or HDTV) the same as described above with respect to the first embodiment of this invention. Also in this ambodiment, the size of the circuitry can be reduced by making the gamma cancellation and gamma addition circuits common for both the NTSC and HDTV systems.
In the above embodiments, the linear matrix circuits are positioned at the initial stage in the drive circuit as shown in Figure 12. However, these circuits may be positioned at a later stage as well. Note tha~ the display p:rimary color chromaticities are set by the white lamp and the optical system so that they include the transmission primary color chromaticities of multiple systems, such as NTSC and HDTV. However, the chroma~icity ranges o~ an NTSC system clearly are distinguished from those o~ other systams but include the other systems as shown in Figures 4 and 5.
Note, however, that the chromaticity of blue has little influence on visual ef~ects in comparison with other colors as the differences between the chromaticity of blu~ in the NTSC and HDTV
systems is not ~reat. Thus, even when the display primary color ,, .,: ~ . ~
-2~ 21~ 3 chromaticitles are set to NTSC values in this embodiment, nearly the same visual effect can be achieved as in the previously discussed embodiments. In this case, the linear matrix circuit for the NTSC system can be omitted, thus reducing the sizé and cost of the circuitry.
As descrLbed above, the present invention provides a display apparatus in which the transmitted colors can be faithfully reproduced, even when receiving television signals from multiple systems with differing transmission specifications and forma1ts.
The present invention also includes a display which can provide natural gradation rendering for the various transmission systems.
While the present invention has been illustrated and described in detail in the drawings and fore~oi,ng description, it will be recognized that changes and modificatiLons can and will occur to those skilled in the art. It is there~ore intended by the app~ing claims, to cover any such changes and modificaltions as fall within the true spirit and scope vf the invsntion.
: ~ ' ., ' :
- ~ .
'
Claims (12)
1. Television receiving apparatus for receiving and displaying television signals distributed in a plurality of formats, said television apparatus comprising:
input means for receiving said television signal;
color error correction means coupled to said input means for correcting color reproduction errors associated with the received television signal and providing a corrected television signal;
display means coupled to said color error correction means for receiving said corrected television signal and displaying a television image in accordance with said corrected television signal, said display means having a reproduction chromaticity range sufficiently wide to include essentially all of the transmission chromaticity range in said received television signal; and control means coupled to said color error correction means for controlling the operation of said color error correction means in accordance with the format of said received television signal.
input means for receiving said television signal;
color error correction means coupled to said input means for correcting color reproduction errors associated with the received television signal and providing a corrected television signal;
display means coupled to said color error correction means for receiving said corrected television signal and displaying a television image in accordance with said corrected television signal, said display means having a reproduction chromaticity range sufficiently wide to include essentially all of the transmission chromaticity range in said received television signal; and control means coupled to said color error correction means for controlling the operation of said color error correction means in accordance with the format of said received television signal.
2. Television receiving apparatus as claimed in claim 1, further comprising:
white color setting means for setting a display white color temperature in said corrected television signal in accordance with the format of said received television signal.
white color setting means for setting a display white color temperature in said corrected television signal in accordance with the format of said received television signal.
3. Television receiving apparatus as claimed in claim 1, wherein said display means is a projection-type display and includes:
a lamp for emitting a white light;
a plurality of optical components for extracting a plurality of colored light beams from said white light;
a plurality of liquid crystal panels for modulating said colored light beams according to said corrected television signal in order to produce image light beams for displaying said television image; and wherein said reproduction chromaticity range is achieved by varying characteristics of said lamp and said optical components.
a lamp for emitting a white light;
a plurality of optical components for extracting a plurality of colored light beams from said white light;
a plurality of liquid crystal panels for modulating said colored light beams according to said corrected television signal in order to produce image light beams for displaying said television image; and wherein said reproduction chromaticity range is achieved by varying characteristics of said lamp and said optical components.
4. Television receiving apparatus as claimed in claim 1, wherein said color error correction means includes a first linear matrix circuit having a plurality of coefficients selected for a first format of said plurality of formats for correcting said color reproduction errors caused by a difference between said reproduction chromaticity range and said transmission chromaticity range of said first format.
5. Television receiving apparatus as claimed in claim 4, wherein said color error correction means includes a second linear matrix circuit having a plurality of coefficients selected for a second format of said plurality of formats for correcting said color reproduction errors caused by a difference between said reproduction chromaticity range and said transmission chromaticity range of said second format, wherein said first and second linear matrix circuits are controlled by said control means.
6. Television receiving apparatus as claimed in claim 1, further comprising:
gamma cancellation means for cancelling transmission gamma correction from said received television signal prior to correction by said color error correction means; and gamma addition means for adding a predetermined gamma correction independent of the format of said received television signal to said television signal after correction by said color error correction means.
gamma cancellation means for cancelling transmission gamma correction from said received television signal prior to correction by said color error correction means; and gamma addition means for adding a predetermined gamma correction independent of the format of said received television signal to said television signal after correction by said color error correction means.
7. Television receiving apparatus for reproducing a colored image transmitted by a television signal in any one of a plurality of systems with differing transmission specifications, said apparatus comprising:
input means for receiving a television signal;
detection means coupled to said input means for receiving said television signal and detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of said television signal;
color error correction means for correcting color reproduction errors associated with said received television signal in accordance with said control signal and providing a corrected television signal;
white color setting means for setting a display white color temperature in accordance with said control signal and the system of said television signal; and display means having a reproduction chromaticity range wider than the transmission chromaticity ranges of each of the systems of said plurality of systems, said display means displaying a television image in accordance with said corrected television signal and said display white color temperature.
input means for receiving a television signal;
detection means coupled to said input means for receiving said television signal and detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of said television signal;
color error correction means for correcting color reproduction errors associated with said received television signal in accordance with said control signal and providing a corrected television signal;
white color setting means for setting a display white color temperature in accordance with said control signal and the system of said television signal; and display means having a reproduction chromaticity range wider than the transmission chromaticity ranges of each of the systems of said plurality of systems, said display means displaying a television image in accordance with said corrected television signal and said display white color temperature.
8. Television receiving apparatus as claimed in claim 7, further comprising:
gamma cancellation means for cancelling transmission gamma correction from said received television signal;
matrix means having a plurality of coefficients for multiplying said received television signal by said coefficients;
and gamma addition means for adding a predetermined gamma correction independent of the system of said television signal to said corrected television signal.
gamma cancellation means for cancelling transmission gamma correction from said received television signal;
matrix means having a plurality of coefficients for multiplying said received television signal by said coefficients;
and gamma addition means for adding a predetermined gamma correction independent of the system of said television signal to said corrected television signal.
9. Television receiving apparatus as claimed in claim 7, wherein said display means is of a projection-type and includes a plurality of optical components and a plurality of liquid crystal panels, wherein said optical components generate a red color beam, a green color beam and a blue color beam, said red, green and blue beams being modulated by said liquid crystal panels in accordance with said corrected television signal.
10. A method for reproducing a color image transmitted by a television signal in any one of a plurality of systems with differing transmission specifications, said method comprising the steps of:
receiving said television signal and providing a received television signal;
detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of said television signal;
correcting color reproduction errors associated with the received television signal in accordance with said control signal and providing a corrected television signal; and driving a display device having a reproduction chromaticity range set sufficiently wide to include the transmission chromaticity ranges of said plurality systems in accordance with said corrected television signal and displaying said colored image.
receiving said television signal and providing a received television signal;
detecting which system of said plurality of systems is used for said television signal and generating a control signal which indicates the system of said television signal;
correcting color reproduction errors associated with the received television signal in accordance with said control signal and providing a corrected television signal; and driving a display device having a reproduction chromaticity range set sufficiently wide to include the transmission chromaticity ranges of said plurality systems in accordance with said corrected television signal and displaying said colored image.
11. A method as claimed in claim 10, wherein the method further comprising the step of:
setting a display white color temperature in said corrected television signal according to said control signal and the system of said television signal.
setting a display white color temperature in said corrected television signal according to said control signal and the system of said television signal.
12. A method as claimed in claim 11, wherein the method further comprising the steps of:
cancelling transmission gamma correction from said received television signal prior to performing said correcting step; and adding a predetermined gamma correction independent of the system of said television signal to said corrected television signal after performing said correcting step.
cancelling transmission gamma correction from said received television signal prior to performing said correcting step; and adding a predetermined gamma correction independent of the system of said television signal to said corrected television signal after performing said correcting step.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JPP04-230367 | 1992-08-28 | ||
| JP4230367A JPH0678318A (en) | 1992-08-28 | 1992-08-28 | Projection type liquid crystal display device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2104443A1 CA2104443A1 (en) | 1994-03-01 |
| CA2104443C true CA2104443C (en) | 1998-07-28 |
Family
ID=16906750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002104443A Expired - Fee Related CA2104443C (en) | 1992-08-28 | 1993-08-19 | Apparatus for receiving and displaying color television signals having different formats |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5301017A (en) |
| JP (1) | JPH0678318A (en) |
| CA (1) | CA2104443C (en) |
| NL (1) | NL9301477A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5905540A (en) * | 1994-12-27 | 1999-05-18 | Seiko Epson Corporation | Projection-type display apparatus |
| WO1996020569A1 (en) * | 1994-12-27 | 1996-07-04 | Seiko Epson Corporation | Projector-type display |
| US6198553B1 (en) * | 1995-07-19 | 2001-03-06 | Canon Kabushiki Kaisha | Image processing apparatus and method |
| GB2312121A (en) * | 1996-04-13 | 1997-10-15 | Thomson Multimedia Sa | LCD television projector with lamp aging compensation |
| AU711400B2 (en) * | 1997-05-15 | 1999-10-14 | Matsushita Electric Industrial Co., Ltd. | Display signal processing device and LED display system |
| JP3024622B2 (en) * | 1997-12-24 | 2000-03-21 | 日本電気株式会社 | Image processing device |
| JP2002372618A (en) * | 2001-06-14 | 2002-12-26 | Fujifilm Arch Co Ltd | Red hardening composition for color filter and color filter using the same |
| US6806856B2 (en) * | 2001-08-09 | 2004-10-19 | Microsoft Corporation | Reflective displays with color filter cross-talk compensation |
| KR101030534B1 (en) * | 2003-12-24 | 2011-04-21 | 엘지디스플레이 주식회사 | Method and Apparatus of Driving Liquid Crystal Display Device |
| JP4533156B2 (en) * | 2004-02-02 | 2010-09-01 | キヤノン株式会社 | Adjustment circuit and method |
| JP4400644B2 (en) * | 2007-04-18 | 2010-01-20 | セイコーエプソン株式会社 | Image processing apparatus, color correction table generation apparatus, display apparatus, and image processing method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4167750A (en) * | 1975-02-20 | 1979-09-11 | Matsushita Electric Industrial Co., Ltd. | Color-difference signal modifying apparatus |
| JPS5723478A (en) * | 1980-07-19 | 1982-02-06 | Akihiro Hagiwara | Device for confirming battery |
| US4553157A (en) * | 1983-12-05 | 1985-11-12 | Rca Corporation | Apparatus for correcting errors in color signal transitions |
| JPH02237280A (en) * | 1989-03-10 | 1990-09-19 | Hitachi Ltd | Standard/high definition television receiver |
| GB9001429D0 (en) * | 1990-01-22 | 1990-03-21 | British Broadcasting Corp | Improvements in television |
| NL9100174A (en) * | 1991-02-01 | 1992-09-01 | Philips Nv | COLOR IMAGE DISPLAY AND COLOR CAMERA. |
-
1992
- 1992-08-28 JP JP4230367A patent/JPH0678318A/en active Pending
-
1993
- 1993-08-11 US US08/104,553 patent/US5301017A/en not_active Expired - Fee Related
- 1993-08-19 CA CA002104443A patent/CA2104443C/en not_active Expired - Fee Related
- 1993-08-26 NL NL9301477A patent/NL9301477A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0678318A (en) | 1994-03-18 |
| CA2104443A1 (en) | 1994-03-01 |
| US5301017A (en) | 1994-04-05 |
| NL9301477A (en) | 1994-03-16 |
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