CA2219929A1 - Printing job make-up system - Google Patents

Abstract

A method of printing a multi-page job including producing separate non-bit mapped files for each page of the multi-page job, producing a page file for each page of the multi-page job, storing the page files in a memory and printing the page files in sequence. The page file may include color separations for the various colors to be printed on the page or other convenient forms of storage devoted to a single page. The page file may be in a bit mapped format or may be in the form of a continuous tone image in a format which can be easily converted into a bit-map format by the printer during the printing process. Preferably, the continuous tone image can be converted into a bit map for printing on the fly.

Description

PRlN'l'l~ JOB MAKE-UP SYSTEM

3 The present invention is relates to printing of images 4 in general and, more particularly, to methods for printing 5 multi-page images.

7 Electronically based printing can be divided into three 8 parts. In the first part an image, which may consist o~ text 9 only, images only, line drawings only or any combination of 10 text images or line drawings is formed into an text or 11 combination text and image file. In general, long files 12 require more than one page for printing and the files 13 represent more than one page of text and/or image.

14 When this information is to be directly printed from 15 the application which generates the file, the application 16 paginates the file and sends it to the printer in a form 17 which the printer can use, for example in the form of a bit 18 map or other such ~orm.

19 In the preparation of films for o~fset printing a 20 number of pages are generally printed at the same time on a 21 large sheet in a mutual orientation suitable for subsequent 22 ~olding and slitting in the manu~acture of a multi-page 23 document such as a book or magazine. Moreover, it is 24 customary to treat each such multi-page sheet as a single 25 file. When the film is to be generated, the multi-page file 26 is trans~ormed into a bit mapped image which is used to 27 expose the film. Similarly, when printing is direct, i.e., 28 without an intermediate film, the entire ~ile is bit-mapped 29 together for printing.
Thus, i~ one page o~ a multi-page file is to be 31 changed, the entire file must be remapped, a rather time 32 consuming process.
33 WO 95/02224 discloses a system for making up pages in 34 which bit-mapped sub-page elements are stored in a memory 35 and are organized into a page prior to printing.

WO 96/35182 PCT/~L96/00193 SIJM~RY OF THE INVENTION
2 The present invention seeks to provide a system in 3 which the delays and down time associated by last minute 4 changes are reduced or eliminated.
This is accomplished by generating a separate set of 6 files, designated collectively herein as a "page file" for 7 each page from image data provided by an application such as 8 page make-up software or word processing and postscript type 9 applications. The page file may include color separations 10 for the various colors to be printed on the page or other 11 convenient forms of storage devoted to a single page. The 12 page file may be in a bit mapped format or may be in the 13 form of a continuous tone image in a format which can be 14 easily converted into a bit-map format by the printer during 15 the printing process. Preferably, the continuous tone image 16 can be converted into a bit map for printing on the fly.
17 There is thus provided, in accordance with a preferred 18 embodiment of the invention, a method of printing a multi-19 page job comprising:
producing separate non-bit mapped files for each page 21 of the multi-page job;
22 producing a page file for each page of the multi-page 23 job;
24 storing the page files in a memory; and printing the page files in sequence.
26 In a preferred embodiment of the invention the method 27 includes:
28 producing at least one replacement non-bit mapped file 29 for one of the pages of the multi-page job to replace one of 30 the pages for which a page file has been previously 31 generated;

32 producing a replacement page file for the replacement 33 page; and 34 storing the replacement page file in the memory, wherein the replacement page file is printed in the 36 sequence in place of the page being replaced.

WO96/35182 PCT~L96/00193 1 There is further provided, in accordance with a 2 preferred embodiment of the invention, a method of preparing 3 a a multi-page job for printing comprising:
4 producing separate non-bit mapped files for each page 5 of the multi-page job;
6 producing a page file for each page of the multi-page 7 job;
8 storing the page files in a memory;
9 producing at least one replacement non-bit mapped file 10 for one of the pages of the multi-page job to replace one of 11 the pages for which a page file has been previously 12 generated;
13 producing a replacement page file for the replacement 14 page; and storing the replacement page file in the memory.
16 Preferably, the method further comprises:
17 printing the multi-page file with the replacement page 18 replacing the page which has been replaced.
19 In one preferred embodiment of the invention, the page 20 file comprises at least one bit mapped image of the page. In 21 a second preferred embodiment of the invention, the page 22 file comprises a continuous tone file adapted for on-the-fly 23 conversion to a bit map during printing.
24 In a preferred embodiment of the invention the page 25 file is stored in compressed form in the memory.

27 The present invention will be understood and 28 appreciated more fully from the following detailed 29 description, taken in conjunction with the drawings in 30 which:
31 Fig. 1 is a block diagram of a system for converting a 32 page file into printing commands for a laser writing head 33 and 34 Fig. 2 is a more detailed block diagram of a screening 35 system of Fig. 1.

2 The prior art situation has been considered acceptable, 3 especially for low resolution systems or for systems which 4 operated off-line from the printing system, for example film 5 preparation systems. In low resolution systems, the bit-6 mapping operation is not time consuming and is a relatively 7 small overhead on the total printing operation. For such 8 systems the computer software bit maps the image and 9 transfers the bit mapped image a page at a time to the 10 printer for printing. Since the resolution is generally low, 11 the waiting time after the first printed page is generally 12 negligible. For off-line systems the speed of the bit-13 mapping operation is not a factor in the print room since 14 only the final films are used for printing.
In high speed direct printing machines, such as the E-16 Print 1000 (Indigo, N.V., The Netherlands) the printing 17 speed is greater than the bit-mapping speed for normally 18 coded images or for postscript images. Thus, in this 19 equipment, bit-maps or intermediate files which store the 20 bit mapped or continuous tone information (or a combination 21 of the two) in a convenient real time convertible format, 22 are generally prepared in advance and stored in a memory 23 within the printing machine. The process of converting a 24 standard format file into a bit mapped or other real time 25 convertible format is referred to herein by the shorthand 26 term "crunching." Print jobs are then ~ueued, converted to 27 bit-map if necessary, and printed in turn.
28 Thus, if a multi-page job must be changed after it is 29 crunched, a delay in the printing process may result and, in 30 extreme cases, in some downtime on the printer may result.
31 Since this printer also includes the facility o~ previewing 32 of the bit mapped images prior to printing, the chances of 33 last minute changes are increased.
34 In order to solve this problem, the present invention 35 provides a method by which each individual page of a print 36 job is supplied to the printing machine in a separate file.

WO 96/35182 PCI/Nl.96/00193 1 The printer groups these files into a job which is the basic 2 printing unit. When the image is crunched and stored a job 3 file is created which contains the memory addresses of the 4 individual page files. As an important part of this process, 5 when a print job is prepared for printing, the software used 6 (which may produce a postscript output file or a file having 7 a different format) is commanded to produce each page in a 8 separate file, generally by requesting each page separately.
9 Each file is then separately crunched and stored in the 10 memory of the printer in under its job number and page 11 number, each page being stored in an identifiable and 12 replaceable page file.
13 When the job is to be printed, the job file instructs 14 the system to print the pages sequentially in accordance 15 with the original sequence of the pages. For larger pages in 16 which several pages are printed on a sheet, in a sequence 17 and orientation consistent with a later folding operation, 18 the individual pages are positioned and orientated in a 19 manner consistent with the final desired printed sheet.
If a page within the job must be changed after 21 crunching, it is not necessary to crunch the entire job, 22 only the new (replacement) page need be crunched. This new 23 crunched page is stored in the printer memory and the job 24 file is amended to indicate the new address of the stored 25 page.
26 Preferably, the crunched images include compression to 27 save storage space. Preferably, a run-length compression 28 algorithm as described below is used for compression of the 29 bit-mapped image prior to storage.
Additionally, in a preferred embodiment of the 31 invention, the job file may be used to tie together units 32 which are smaller than a full page. In this embodiment, the 33 application software which prepares the text and/or images 34 prepares a plurality of files, at least some of which are 35 smaller than a full page. In total, the files cover all of 36 the full pages. In practice, the job file keeps track of the 1 positions of the files in the printing cycle and of their 2 addresses in memory. When the job is printed, the files are 3 either read sequentially of combined to form a single 4 printing file.
Replacement of a portion of a page file (congruent with 6 a page) is performed in the same way as a full page 7 replacement.
8 As indicated above, the page file may be in compressed 9 bit mapped form or in the form of a continuous tone image 10 (optionally combined with bit mapped portions) in a format 11 which can be easily converted into a bit-map format by the 12 printer during the printing process. A preferred embodiment 13 of such a format is based on cells containing a 4x4 matrix 14 of pixels with a pixel resolution of 800 DPI.
These cells are of two kinds. One kind of cell is a 16 simple bit-mapped, bi-level cell. For these cells, the 17 information on which levels are high and which are off, is 18 stored in a vector form. If a number of contiguous cells are 19 bit mapped a first word indicates that this is the case, a 20 second word indicates the number of cells which are bit 21 mapped. The vectors for these cells are then listed without 22 additional definition of the cells. Such a group of cells 23 may be of any length; however, in a practical preferred 24 embodiment o~ the invention, the length is limited to 256, 25 the length which is definable by an 8 bit word.
26 For cells which are defined in terms of a continuous 27 tone, there are two possibilities. One possibility is that 28 all of the pixels have the same or similar pixel values. In 29 this case the average value of the continuous tone, is 30 provided for the cell at a resolution of preferably 128 gray 31 levels. Where a number of contiguous cells have the same 32 value, a special word is used to indicate this fact, a 33 second word indicates the number of cells (up to 256) which 34 have the same value and a third word gives the gray level 35 value for the run of cells.~6 If the variation of the continuous tone values within 1 the cell is greater than a given amount, i.e., there is an 2 edge within the cell, then two types of information are 3 stored. One type of information is the two gray levels which 4 correspond relatively closely to the gray levels on the two 5 sides of the edge. Since the eye does not discern the exact 6 gray levels near an edge, the number of combinations is 7 reduced from the theoretical number possible and only about 8 120 combinations are available. The second type of 9 information which is stored is the position of the edge in 10 the form of a vector which describes which pixels have which 11 of the two values. This vector has the same form as the 12 defining vector for the bi-level, bit-mapped image. Israel 13 patent application 112,561 which was filed on February 6, 14 1995 and corresponding PCT application titled "High 15 Resolution Imaging" filed as PCT\NL95\00200 on June 6, 1996, 16 the disclosures of which are incorporated herein by 17 reference, give additional information on such a system.
18 The choice of a 4x4 cell is based on practical 19 considerations such as the spatial and gray level resolution 20 which is discernible by a viewer and compression e~iciency.
21 In practice, an 8 bit word is the basic coding unit.
22 256 codes are available ~rom an 8 bit word; 128 codes are 23 used to define the 128 continuous tone gray levels which are 24 printed for single level cells and 120 codes are used to 25 define the reduced set of combinations of gray levels ~or a 26 continuous tone edge cell. One code is used to indicate that 27 the next cell is to be bit mapped, one code is used to 28 indicate that the multiple cells are bit mapped and one code 29 is used to indicate a situation in which a plurality of 30 contiguous cells have the same value. A special code is used 31 to indicate a run length followed by a bit mapped cell. Such 32 situations are found in text printing.
33 This type of code can be decoded by a decoder to bit 34 map system such as that shown, in block diagram form if Fig.
35 1. In Fig. 1 a word is asynchronously fed from a bus 10 via 36 a bus interface 12 and a FIFO 14 to a decompression system WO 96/3~182 PCT/~L96/00193 1 16 which converts the compressed data in the above format to 2 decompressed data, namely, continuous tone data based on 3 descriptors for single cells, be they continuous tone cells, 4 bi-level cells or bit-mapped cells. Decompression of 5 compressed data is well known in the art. This cell 6 descriptor information is sent asynchronously, via a second 7 FIF0 18 to a screening system 20 which converts the cell 8 descriptor information into bit map information in a manner 9 which is suitable for activation of a laser printer, for 10 example one having four parallel independently addressable 11 lasers.
12 The output of the screening system is sent, 13 asynchronously via four FIFOs 21 to a pulse width modulation 14 system 22 for activation of the lasers.
The flow of data to the lasers is controlled by a 16 configuration control module 23 which receives information 17 on the position of the image on the printed page and whether 18 the system is ready to print the next group of pixels and on 19 this basis controls transfer of the data from the screening 20 system to lasers. It should be understood that data is 21 transmitted asynchronously between modules up until FIF0 21.
22 At this point the data is transmitted in accordance with the 23 position of the lasers vis-a-vis the imaging surface of the 24 printer.
A preferred embodiment of screening system 24 is shown 26 in Fig. 2. An 8 bit code for which describes the continuous 27 tone level (or the reduced set of two continuous tone levels 28 for an edge cell) is received by a convertor/look up table 29 30 which produces two 8 bit signals giving the high and low 30 values of continuous tone for the edge case or an 8 or 31 greater bit signal for a single continuous tone cell. These 32 signals are sent to a screen convertor 32 for conversion to 33 a stream of bit mapped data.
34 A 16 bit vector descriptor which describes the edges of 35 either the continuous tone (two level) cell or the matrix of 36 a bi-level cell is received by a vector convertor 34 which 1 sends a 4 bit comm~n~ signal to the screen convertor. This 2 four bit signal is sent at the rate at which a column of 3 pixels in a cell are printed, i.e., at four times the cell 4 rate. This vector is active only if the cell is a bi-level 5 cell (in which case the convertor ignores any information it 6 receives from look-up table 30 or vector convertor 34 and 7 prints an on or off pixel based on the 4 bit signal) or a 8 two level continuous tone cell (in which case the 4 bit 9 signal informs the screen convertor whether the level is the 10 high or low continuous tone level).
11 In a preferred embodiment of the invention, rational 12 screening angles are used. Screen convertor 32 includes a 13 look up table (on-off bit maps) for each gray level and 14 combination on a matrix size equal to the smallest repeat of 15 the rational angle matrix. A position computer 36, informs 16 the screen convertor of the position within the repeat 17 occupied by the next column of four pixels. It calculates 18 this position based on a knowledge of the repeat matrix size 19 and the image width, both of which are fixed for a given 20 page. The screen convertor then need only look-up the bit 21 value on the matrix corresponding to the gray level and pass 22 this on to the laser printer.
23 The output of the screening convertor is a 3 bit signal 24 which represents the gray level to be printed for a given 25 pixel (at 800 DPI). These signals are converted to pulse 26 width modulation signals by pulse width modulators 22 which 27 modulate the laser at a higher rate than the pixel rate, 28 depending on the speed with which the laser can be switched.
29 It will be appreciated by persons skilled in the art 30 that the present invention is not limited by the description 31 and example provided hereinabove. Rather, the scope of this 32 invention is defined only by the claims which follow:

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Claims (7)

1. A method of printing a multi-page job comprising:
producing separate non-bit mapped files for each page of the multi-page job;
producing a page file for each page of the multi-page job;
storing the page files in a memory; and printing the page files in sequence.

2. A method of printing according to claim 1 and comprising:
producing at least one replacement non-bit mapped file for one of the pages of the multi-page job to replace one of the pages for which a page file has been previously generated;
producing a replacement page file for the replacement page; and storing the replacement page file in the memory, wherein the replacement page file is printed in the sequence in place of the page being replaced.

3. A method of preparing a a multi-page job for printing comprising:
producing separate non-bit mapped files for each page of the multi-page job;
producing a page file for each page of the multi-page job;
storing the page files in a memory;
producing at least one replacement non-bit mapped file for one of the pages of the multi-page job to replace one of the pages for which a page file has been previously generated;
producing a replacement page file for the replacement page; and storing the replacement page file in the memory.

4. A method according to claim 3 further comprising:
printing the multi-page file with the replacement page file replacing the page which has been replaced.

5. A method according to any of the preceding claims wherein the page file comprises at least one bit mapped image of the page.

6. A method according to claim 5 wherein the bit mapped images are stored in compressed form.

7. A method according to any of the preceding claims wherein the page file comprises a continuous tone file adapted for on-the-fly conversion to a bit map during printing.