JP2001306275A - Image processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing system capable of satisfactorily outputting band-divided image data without complicating any constitution or processing. SOLUTION: This image reprocessing system is provided with a host computer 1 and a printer 2. The host computer 1 is provided with an OS 4 for performing band formation processing by dividing image data for one page into plural bands by overlapping the boundary of the adjacent bands and a printer driver 5 for performing data compression processing by compressing the picture data in each divided band. The printer 2 is provided with an expander 11 for expanding the image data in each band compressed by the data compression processing and a CPU 9 for transmitting the image data expanded by the expander 11 to a printing part 13 by removing the overlapped part of the band boundary positioned at the opposite side to a sampling starting edge in compressing the image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention generally relates to a printing system, and more particularly to an image processing system suitable for use in a printing system.

[0002]

2. Description of the Related Art One page of image information created by a word processor, desktop publishing system, or the like is composed of "characters" such as alphanumeric characters, katakana, and kanji.
And "graphics" such as circles and straight lines, and "natural images" generated by a scanner or the like. Normally, when such image information is printed (image output) by a printer or the like, an image for one page is developed in a page memory and supplied to a printer engine. However, in that case, a large-capacity memory is required to develop an image for one page.

[0003] Therefore, conventionally, the memory capacity is reduced by dividing one page of image information into a plurality of bands and processing the image data of each of the divided bands in band units. In this conventional technique, after one page of image information is divided into a plurality of bands and arranged,
The image data of each band is compressed by a predetermined sampling block, and then, when the image data is transmitted to the printer engine, the image data of each band that has been compressed is expanded and expanded.

[0004]

However, in the prior art, when the image data of each band obtained by being divided into a plurality of bands is expanded and connected, image distortion occurs at the joint of the bands, There was a problem that good elongation results could not be obtained.

In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 5-104786 discloses a method of sequentially expanding image data (compressed data) of each band until the next band expansion process is started. A technique for holding image data of a processed band is described.

However, in the technique described in the above publication, a memory for holding the image data of the previous band is required when the image data of the band is expanded, as a configuration of the printer or the like. In addition, when decompressing image data of a predetermined band, it is necessary to add a processing function using image data of another band, which complicates the configuration and processing of the entire apparatus and increases the manufacturing cost of a printer or the like. Would.

[0007]

In an image processing system according to the present invention, one page of image data is divided into a plurality of bands, and upon dividing the band, the boundary between adjacent bands is overlapped and divided. Band forming means, data compressing means for compressing image data of each band divided by the band forming means, data expanding means for expanding image data of each band compressed by the data compressing means, and data expanding means Means for transmitting the image data decompressed by the means to the image output unit, and at the time of the data transmission, removing the overlapping portion of the band boundary located on the opposite side to the sampling start end when the image data is compressed by the data compression means. A configuration including data transmission means for transmitting is adopted.

According to the image processing system having the above configuration, 1
When the image data for a page is divided into a plurality of bands by the band forming unit, the division is performed by overlapping the boundaries of adjacent bands. Further, the image data of each band is compressed by the data compression unit, and the compressed image data is expanded by the data expansion unit. When transmitting the decompressed image data to the image output unit by the data transmission unit, the overlapping part of the band boundary located on the side opposite to the sampling start end when the image data is compressed by the data compression unit is removed. To send. As a result, it is possible to transmit only image data that has been appropriately compressed by the data compression unit and appropriately decompressed by the data decompression unit to the image output unit.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a printing system using an image processing system according to the present invention.
The illustrated printing system mainly includes a host computer 1 and a printer 2. The host computer 1 and the printer 2 are connected by a parallel cable (such as a Centronics I / F cable) for data communication.
And are connected to each other via a network cable or the like.

The host computer 1 is composed of a personal computer, a workstation, and the like. The host computer 1 has application software (hereinafter, abbreviated as “application”).
3, an OS (Operating System) 4, a printer driver 5, and an output interface (output I / F) 6. Application 3, O
S4 and the printer driver 5 are connected to the host computer 1
(A hard disk or the like), a floppy (registered trademark) disk, or a program written in a storage medium such as a CD-ROM.

The application 3 is used when the host computer 1 creates image data. The OS 4 manages the execution of various programs and the management of peripheral devices in the host computer 1. The printer driver 5 is incorporated in correspondence with the printer 2 connected to the host computer 1, and performs predetermined data processing when, for example, printing image data created by the application 3.
The output interface 6 is a communication interface for transmitting image data to the printer 2.

On the other hand, the printer 2 has an input interface (input I / F) 7, an input buffer 8, a CPU (central processing unit) 9, and a ROM (read only memory) 1.
0, expander 11, band buffer 12, and image output unit 1
3 having a common bus 1
4 is connected.

The input interface 7 is a communication interface for receiving image data transmitted from the host computer 1 side. The input buffer 8 is for storing image data input via the input interface 7.

The CPU 9 controls the overall processing of the printer 2, and a control program therefor is stored in the ROM 10. The decompressor 11 performs a process of decompressing the compressed image data. Band buffer 12
Is used when the image data expanded by the expander 11 is expanded (drawn). Printing unit 13
Prints out the image data developed in the band buffer 12, and corresponds to the image output unit in the present invention.

Next, the processing functions of the printing system having the above configuration will be described.

FIG. 2 is a flowchart showing a processing procedure on the host computer 1 side. This flowchart shows the processing procedure of the printer driver 5 when printing one page of image data created by the application 3.

First, in the host computer 1,
The OS 4 sequentially notifies the printer driver 5 of the band area (band number) in response to the print request for the image data.
Then, the printer driver 5 performs the processing of FIG. 2 every time the OS 4 notifies the band area. By the way, O
From S4, the first band, the second band, the third band,
The band area is notified in the order of.

Then, in step S11,
It is determined whether the band area notified from the OS 4 is the first band. At this time, since the band region notified first is the first band, Yes is determined in step S11.
And the process moves to step S12.

In step S12, coordinates for designating the area of the first band are calculated. The size of the band depends on various paper sizes (A4, B5, B4, A3, etc.)
And the memory capacity of the band buffer 12 of the printer 2 or the like. Therefore, in step S12, the coordinates of the first band are calculated according to the preset size. Next, in step S13,
The OS 4 is notified of the previously calculated band coordinates.

Thereafter, when the band area (band number) is notified from the OS 4, it is determined whether or not the band is the first band in step S11 as described above. In this case, since the second band is notified, No is determined in step S11, and the process proceeds to step S14.

In step S14, 8 pixels (pi) are applied to the band processed last time (the first band at this time).
xel) Calculate the coordinates of the overlapping bands. Then, in step S13, the OS 4 is notified of the coordinates of the band calculated in step S14.

Thereafter, the same processing is performed each time a band area is notified from the OS 4, so that the coordinates (size) of each band are sequentially notified to the OS 4. On the other hand, O
On the S4 side, a process of dividing one page of image data into a plurality of bands is performed according to the coordinates of the bands notified from the printer driver 4. Incidentally, the number of band divisions for dividing image data for one page is appropriately set according to, for example, the size of the image data and the size of the paper on which the image data is printed.

FIG. 3 shows a conceptual diagram of band division. As illustrated, the image data 20 for one page is divided into three bands, for example, a first band 21, a second band 22, and a third band 23. At this time, the boundary between adjacent bands is divided in such a manner as to overlap by eight pixels calculated in the previous step S14.

That is, the boundary between the adjacent first band 21 and the second band 22 is defined by the overlapping portions 21A and 22 of 8 pixels at the lower end of the first band 21 and the upper end of the second band 22, respectively.
A is provided and divided. In addition, the adjacent second band 22
The boundary between the second band 22 and the third band 23 is located at the lower end of the second band 22 and the upper end of the third band 23, respectively.
B and 23A.

When the image data 20 for one page is divided into a plurality of bands, the bands 21, 22, 23
The image data included in the printer driver 4
Are sequentially notified, and band processing is performed there. At this time,
Each time the OS 4 notifies image data in one band, a band end notification is sent. Upon receiving the band end notification, the printer driver 4 determines the end of each band.

FIG. 4 is a flowchart showing band processing of the printer driver 4. In FIG. 4, step S
At 21, it is determined whether or not the band has ended based on the presence or absence of the band end notification from the OS 4. At this time, when the band image data is notified from the OS 4, the determination is No, and the process proceeds to step S22.

In step S22, it is determined whether or not the notified image data needs to be compressed. Regarding the compression of image data, for example, if the image data notified from the OS 4 includes only black-and-white image data, a sufficient compression effect cannot often be obtained even if the image data is compressed. On the other hand, if the image data notified from the OS 4 includes multi-valued (color) image data, a high compression effect can be obtained by compressing the image data. For this reason, in step S22, for example, if the image data notified from the OS 4 includes multi-valued image (color image) data, it is determined that compression is necessary, and only black-and-white image data not including multi-valued image data is determined. In the case of, it is determined that compression is unnecessary.

If it is determined in step S22 that compression is necessary, the process proceeds to step S23, where the coordinates of a sampling block of 8 × 8 pixels with the upper end of the band as a boundary are calculated. Next, in step S24, the image data is compressed for each sampling block partitioned by the above calculation. Incidentally, in the present embodiment, the JPEG method is adopted as the compression method of the image data.

FIG. 5 is a schematic diagram showing a sampling method at the time of compressing image data according to the present embodiment. Note that FIG. 5 illustrates a sampling method when compressing the image data of the second band 22. As shown in the figure, the second band 22 has a sampling start end S at the upper end of the band.
It is partitioned into sampling blocks of 8 pixels × 8 pixels (length × width) as p. Then, the image data in the second band 22 is JPEG-compressed for each block.

After the band image data is compressed in this way, the compressed image data is transmitted to the output interface 6 in step S25. On the other hand, if it is determined in step S22 that the compression of the image data is unnecessary, the process proceeds to step S25, and the image data notified from the OS 4 is transmitted to the output interface 6 as it is.

Thereafter, when a band end notification is sent from the OS 4, a band end is determined in step S21, and the process proceeds to step S26. In this step S26, a band end command is transmitted to the output interface 6.

Thereafter, the image data of the next band is stored in OS4
The same processing as described above is performed each time a notification is sent from the server. Thus, the first band 21, the second band 22, and the third band 23 are output from the output interface 6 of the host computer 1.
Image data (including compressed image data) corresponding to
Is transmitted in band units. In addition, a band end command is added to the transmission data for each band.

The image data transmitted from the host computer 1 is received by the input interface 7 of the printer 2 together with the band end command. The image data received by the input interface 7 is stored in the input buffer 8.

When the coordinates of a sampling block of 8 × 8 pixels are set based on the upper end of the band as shown in FIG. 5, the boundary of the sampling block does not coincide with the band boundary at the lower end of the band. As a result, an odd block smaller than 8 pixels × 8 pixels may exist. Since the image data of such odd blocks is not appropriately processed (compressed or decompressed), it appears as image distortion during printing. Therefore, in the CPU 9, the ROM 1
The following data processing is executed according to the control program stored in “0”.

FIG. 6 is a flowchart showing the processing procedure of the CPU 9. First, in step S31, it is determined whether the data received by the input interface 7 is image data. If it is determined that the data is image data, the process proceeds to step S32. Then, step S32
, The image data stored in the input buffer 8 is extracted and transferred to the decompressor 11.

As a result, in the decompressor 11, FIG.
It is determined whether or not image data needs to be decompressed in accordance with the processing procedure shown in (1) (step S41). Here, it is determined that expansion is necessary when the image data extracted from the input buffer 8 is compressed, and it is determined that expansion is unnecessary when the image data is not compressed.

If it is determined in step S41 that decompression is necessary, the flow shifts to step S42, where the image data is transferred to the JP
After performing the EG decompression process (restoration process), the process proceeds to step S43. If it is determined in step S41 that decompression is unnecessary, the process proceeds directly to step S43. And step S
At 43, the image data is developed (drawn) in the band buffer 12. The processing of the decompressor 11 is now completed.

On the other hand, if a band end command is received in the processing of the CPU 9 shown in FIG.
At 33, it is determined that the band has ended, and the routine goes to Step S34. In step S34, a bandwidth is calculated by removing the overlapping portion at the lower end of the band that causes image distortion.
The image data to be transmitted is determined. And step S
At 35, the image data of the band buffer determined earlier is transmitted to the printing unit 13.

By the processing of the CPU 9, the image data of each band is transmitted to the printing unit 13 in a form as shown in FIG. That is, the image data of the first band 21 is transmitted in such a manner that the overlapping portion at the lower end of the band (that is, the overlapping portion of the band boundary located on the side opposite to the sampling start end when compressing the image data) 21A is removed. You.
The image data of the second band 21 is transmitted in such a manner that the overlapping portion 22B at the lower end of the band is removed. On the other hand, the image data of the third band 23 is transmitted as it is because there is no overlapping portion at the lower end of the band.

At this time, the first band 21 and the second band 2
In the boundary portion 2, the width (overlap width) of the overlapping portions 21A and 22A is set to 8 pixels, that is, the same as the sampling block width used for the compression processing of the image data. Therefore, the overlapping portion 22A at the upper end of the second band 22
Can be appropriately processed (compressed, decompressed). Also, at the boundary between the second band 22 and the third band 23, the width of the overlapping portions 22B and 23A is set to be the same as the sampling block width. for that reason,
The overlapping portion 23A at the upper end of the third band 23 can be properly processed.

Thus, only the image data appropriately processed (compressed and decompressed) can be transmitted to the printing unit 13. Therefore, when the printing unit 13 combines and prints out the image data of each band, it is possible to output a good print image without causing image distortion at the joint of the bands.

In the above embodiment, the sampling start end when compressing the image data of each band is set as the upper end of the band, and the overlapping portion of the band boundary (lower end of the band) located on the opposite side is removed. However, the present invention is not limited to this. That is, when the sampling start end when compressing the image data of each band is the lower end of the band, the same effect can be obtained by removing the overlapping portion of the band boundary (the upper end of the band) located on the opposite side. .

Further, in the above embodiment, the case where the image data for one page is divided into a plurality of bands in the vertical direction, but other than this, for example, the image data for one page is divided in the horizontal direction. In the case of dividing into a plurality of bands, the same effect can be obtained by adopting the following processing mode. That is, when the sampling start end at the time of data compression is the left end of the band, the overlapping portion of the band boundary (the right end of the band) located on the opposite side is removed, and when the sampling start end is the right end of the band, the opposite side is used. A similar effect can be obtained by removing the overlapping portion of the band boundary (the left end of the band) located at.

In addition, in the above embodiment, the JPEG system is adopted as the image data compression system. However, the present invention is not limited to this, and another data compression system that performs sampling in a specific block unit is employed. The same can be applied to the case.

In the above embodiment, the overlap width of the adjacent band boundary is set to be the same as the sampling block width used for the compression processing of the image data.
The overlap width of the band boundary may be set wider than the sampling block width at the time of data compression.

[0047]

As described above, according to the present invention, 1
When the image data for a page is divided into a plurality of bands, and the image data of each of the divided bands is compressed and decompressed and transmitted to the image output unit, only the appropriately processed (compressed and decompressed) image data is converted to an image. It can be supplied to the output unit. As a result, the image output unit can output a high-quality image without causing distortion at the band joint. In addition, when expanding image data of each band, it is not necessary to use other band data, so that the memory for expansion can be reduced, and the configuration and processing of the entire system can be simplified to reduce manufacturing costs. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a printing system using an image processing system according to the present invention.

FIG. 2 is a flowchart illustrating a processing procedure of a printer driver.

FIG. 3 is a conceptual diagram of band division.

FIG. 4 is a flowchart illustrating band processing of a printer driver.

FIG. 5 is a schematic diagram showing a sampling method at the time of compressing image data.

FIG. 6 is a flowchart illustrating a processing procedure of a CPU.

FIG. 7 is a flowchart showing a decompression process.

FIG. 8 is a conceptual diagram of a data transmission process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Printer, 3 ... Application, 4 ... OS, 5 ... Printer driver, 6 ... Output interface, 7 ... Input interface, 8 ... Input buffer, 9 ... CPU, 10 ... ROM, 11 ... Decompressor, 12: band buffer, 13: printing unit

Claims (2)

[Claims] 1. A band forming unit that divides one page of image data into a plurality of bands, and, at the time of the band division, divides by overlapping boundaries of adjacent bands. A data compression unit for compressing the image data of the band; a data expansion unit for expanding the image data of each band compressed by the data compression unit; and the image data expanded by the data expansion unit is transmitted to an image output unit. And data transmission means for removing the overlapping portion of the band boundary located on the side opposite to the sampling start end when compressing the image data by the data compression means and transmitting the data when transmitting the data. Image processing system. 2. The image forming apparatus according to claim 1, wherein the band forming unit sets an overlapping width of the adjacent band boundaries to be equal to or larger than a sampling block width used for compressing image data by the data compressing unit. The image processing system described in the above.