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METHOD AND DEVICE FOR THE
RECORDING AND REPRODUCTION OF
STEREOSCOPIC VIDEO IMAGES
This application relates to a method and a device for the recording and reproduction of stereoscopic video images. One such method is disclosed in German Publication DE 41 34 033 CI. This method is disadvantageous in that the reproduction quality of the stereo images represented on the 10 monitor is inadequate.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to find a simple and reliable method and a device with which steroscopic 15 video image reproduction quality is ensured.
U.S. Pat. No. 5,084,763 discloses a method and a device for displaying stereoscopic television pictures. The latter can be transmitted and recorded as fields using time-division multiplex, the changeover between left and right channels 20 being performed during reproduction with the timing of a field period. Signal processing is undertaken separately for each channel, and the two channels are displayed on the monitor with double frequency in order to suppress flicker. Nothing is said as to how a distinction is achieved between 25 the images of the right and left channels during reproduction by the VTR.
The video images are generated by two image-acquiring devices, both the signal of the camera assigned to the left eye and the signal of the camera assigned to the right eye having as usual even and odd fields. The invention also comprises an embodiment in which for the sake of simplicity only one field each is generated per image-acquiring device.
In a preferred exemplary embodiment, the signals of the 3J two cameras are fed to an interface (video signal coupler) at whose output the even fields of one camera and the odd fields of the other camera are present successively in time. The output signal of the interface is fed to the recording device.
The assignment of the video fields in the reproduction of the recorded video signal has normally been rendered possible by an identifying signal added to the video signal during recording. This identifying signal has indicated the connection between even and odd fields and right and left 45 cameras. In the reproduction of the recorded video signal, this identifying signal has been used to split the video signal into two channels, one for images assigned to the right eye and one for images assigned to the left eye. On the basis of the invention, this identifying signal is no longer mandatory 50 and is therefore provided only in the case of a modified embodiment.
If, however, the identifying signal is not detected at the reproducing device, for example during a disturbance, the right-left separation of the reproduced video signal cannot 55 be carried out satisfactorily. This problem is also eliminated by the invention. According to the invention, a method is specified in which the separation of the reproduced video signal is possible without the recording of an additional identifying signal. 60
Coupling a synchronization signal to a field achieves the advantage that this signal is directly a component of the video signal, with the result that detection is more easily possible than if it was a question of—as known—a separate signal. 65
One advantage of the invention resides in that the image acquiring devices detect and record by channel odd fields, on
the one hand, and even fields, on the other hand. In each case, one field of the frames consisting of two fields is detected per channel and recorded in a recording device. For reproduction, the fields are further processed by channel and respectively fed to a raster image buffer which is preferably connected in each case to an interpolator for generating the missing field. After joining the image generated by the interpolator with the field already present in the raster image buffer, there is produced per channel a frame consisting of two fields which are read out by a frame grabber with 4-fold picture frequency and made available for reproduction to a reproducing monitor. Whereas the image acquiring devices acquire the frames or raster images with a picture frequency of, for example, 25 Hz, in the reproducing monitor frames or raster images of the first and second channel or, in other words, the right and the left frames or raster images are displayed with a picture frequency of 100 Hz. This leads to a flicker-free impression of the video image for the viewer. A brighter image is achieved by means of the display of raster images instead of fields.
BRIEF DESCRIPTION OF THE DRAWINGS
Further details of the invention are to be gathered from the claims, the Figures and associated parts of the description. In particular, in this case of the Figures
FIG. 1 shows a first exemplary embodiment of a recording part of a device according to the invention with two coordinated CCDs;
FIG. 2 shows a second exemplary embodiment of a recording part with two synchronously controlled video cameras and a video recording device;
FIG. 3 shows a third exemplary embodiment of a recording part with two video recording devices;
FIG. 4 shows a first exemplary embodiment of a reproducing part of a device according to the invention with an interpolation circuit and an interface which permits the display of pairs (VB) of fields on a monitor;
FIG. 5 shows a second exemplary embodiment of a reproducing part in which progressively scanned raster images can be alternately represented on the monitor;
FIG. 6 shows an alternative for the first part of the reproducing part according to FIG. 4 or FIG. 5;
FIG. 7 shows a further alternative for the first part of the reproducing part according to FIG. 4 or FIG. 5;
FIG. 8 shows a third exemplary embodiment of a reproducing part for the continuous processing of complete pairs (VB) of fields (HB) from two video recording devices;
FIG. 9 shows a practical example of an implemented interface with a video recorder input YC/VCR, a video output YC/VCR and two video camera inputs IPM for recording stereoscopic images on a conventional video recorder; and
FIG. 10 shows a temporal progression of the signal sequence in a preferred exemplary embodiment of the invention with raster image display on the monitor.
Identical reference symbols signify identical components. Identical reference symbols with different indices signify similar components.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS List of Reference Symbols and Definition of Terms Within the meaning of the invention: A stereoscopic video image is two correlated frames of a left and right image channel, the frames having at least one
video field (HB), but being designed as a raster image, as the case may be, in which they are constructed from a correlated pair (VB) of two fields (HB). Within the meaning of the invention, such a pair (VB) can also consist of two interlaced fields (HB) or of two simultaneously present and thus no 5 longer separated fields (progressive scan).
Interpolated fields (HB) are fields which have been obtained by computational evaluation of existing image information from a field (HB). Raster images may have been obtained both from HB/A and from HB/B. 10
The designation HB/A stands for fields (HB) of one image channel, while the designation HB/B stands for fields of the associated other image channel. The index X signifies the progressive numbering of the respective field (HB). The index 1 or 2 stands for the respective even or odd field (HB). 15 As a rule, one even and one odd field (HB) are recorded when recording only one field each per frame channel. However, this is not mandatory inasmuch as an additional, for example, synchronization signal at an least one of the two field signals can be used to assign them to the correct 20 channel.
A and C stand for contact parts which are connected to one another in the operational case.
1 Video recording device; this includes, for example,: video recorders, video disk devices, digital storage devices of 25 every sort.
2 Video reproducing device; this includes all devices with which it is possible to reproduce recordings of devices according to 1.
3 Camera electronic system; this includes all devices which 30 electronically acquire images acquired by an optoelectronic recording device and render them processible.
4 Field detector; this includes all signal analyzing devices which can detect a field (for example, an even one) or distinguish it from an associated second field (for example 35 an odd one) and, as the case may be, can undertake suitable changeovers for the purpose of relaying signals.
5 Image acquiring device; this includes still or full-motion video cameras, any CCD or other optoelectronic array circuitry, etc. 40
6 Video signal coupler; this includes all interfaces which switch signals from two parallel channels—in particular alternating—to an electronic path. They can be designed, in particular, as a graphics card.
7 Camera synchronization system; this includes synchroniz- 45 ing elements which both synchronize two camera electronic systems with one another and, as the case may be, clock further elements for the purpose of image processing and/or generate signals which can be recorded if required on video data media. 50
8 Raster image buffer; this includes all storage elements which can store at least two correlated fields of a frame or at least one raster image.
9 Framegrabber; this includes all electronic circuits which convert signals of a video raster image or video field into 55 signals which can be further processed digitally, and which condition them for display on a computer monitor.
11 Monitor; this includes all image displaying devices and displays, in particular cathode ray tubes with a short persistence (for example under 10 ms) as well as LCD 60 displays, etc.
12 Interpolator; this includes devices which create two correlated fields from one field by filling the line interspaces of a field with interpolated image information, preferably obtained from the image information of the 65 two lines of the relevant field which bound the line interspaces.
13 Video divider; divides a video signal from one path into at least two paths so that the same signals are present on both paths.
14 Video amplifier and clamping device; correspond to the conventional devices in video signal processing; these can also be dispensed with under some circumstances, for example in the case of variant E for variant 3.
15 Field buffer; this includes all those storage devices, and therefore also raster image buffers, as the case may be, which can store at least one field.
16 Raster image buffer with interpolation on frame-grabber; these are integrated components which create by interpolation from a field a raster image which they render capable of being retrieved in a form which can be processed by a computer. They also serve to increase the frequency of the displayable images by comparison with the recording frequency on the video recording device. The device for the recording and reproduction of stereoscopic video images consists, on the one hand, of a recording part and, on the other hand, of a reproducing part. Different embodiments of the recording part are represented in FIG. 1, FIG. 2 and FIG. 3. Exemplary embodiments of the reproducing part are represented in FIG. 4 to FIG. 8. The exemplary embodiments of the recording parts, on the one hand, and the reproducing parts, on the other hand, can be combined at will, it being preferred for the third exemplary embodiment of the reproducing part in accordance with FIG. 8 to be assigned to the third exemplary embodiment of the recording part in accordance with FIG. 3, and the two other exemplary embodiments of the reproducing part in accordance with FIG. 4 to FIG. 7 respectively being assigned to the first and second exemplary embodiments of the recording part in accordance with FIG. 1 and FIG. 2, respectively.
According to a first exemplary embodiment of the recording part in accordance with FIG. 1, the frames of a stereo image pair which are assigned to the right and left eyes are recorded by coordinated cameras 5a. The output signals of the two cameras 5a each have even and odd fields HB/A1.1, HB/A1.2 and HB/B 1.1, HB/B 1.2, respectively. The output signals of the cameras 5a are fed to a camera electronic system 3a in which the fields HB are sequentially changed over, the even field HB of the first channel being followed by an odd field HB of the second channel.
Consequently, one channel detects only even fields HB, and the other channel detects only odd fields HB, and these are relayed for the purpose of video recording to a recording device la. According to a second exemplary embodiment of the receiving part in accordance with FIG. 2, there are provided for this purpose two field detectors 4/ which respectively detect even or odd fields HB and relay them to a signal coupler 6a which alternately accepts the incoming fields HB and feeds them to the recording device la. The field detectors 4/ are clocked with the field frequency. A commercially available video recorder is used as recording device la.
For the purpose of reproduction, this video recorder is used as a reproducing device 2a which feeds the stored video data to a video divider 13a. The video divider 13a divides the signals into two channels. Before the further processing of the signals allotted to the two channels, these signals are normalized in accordance with an existing standard by means of a video amplifier and a video clamping device 14a. Thereafter, the even and odd fields HB are separated from one another in the two channels, so that even fields are processed in one of the channels and odd fields are processed in the second channel, see FIG. 6.
Video field detectors 4b, for example type SM II VI.4 from Fast Electronic GmbH, are used for the purpose of