JPH09326944A - Image processing unit, image processing method, print processing system, print processing method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the image processing unit in which image gradation, edges of characters and gradation of a natural image are not degraded and a high quality output is obtained at a high speed by discriminating whether or not there is any part of an image scanned by an image scanning means in excess of a preset threshold. SOLUTION: A CPU 12 expands print data from a host computer 3000 into four bit map images of a basic color according to a module in a program ROM 13b and scans the entire images and discriminates whether or not there is any part in excess of a preset threshold as to the scanned images. When discriminating the presence, color space is converted to the bit map image and the color density of the images is adjusted so that a maximum value of the excess part as to the converted bit map images is a maximum value within the threshold. Thus, a high quality output is obtained at a high speed without degrading image gradation, edges of characters and gradation of a natural image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, an image processing method, a print processing system, a print processing method and a storage medium, and more specifically, an image processing apparatus and an image processing method suitable for color printing. , Print processing system,
The present invention relates to a print processing method and a storage medium.

[0002]

2. Description of the Related Art Conventionally, in a color printing apparatus, the total amount of coloring material per pixel is sometimes limited due to the image forming process in the color printing apparatus. In this case, a threshold value for each pixel is set at the stage of developing each of the basic color material colors of cyan (C), magenta (M), yellow (Y), and black (K) bitmap images, The bitmap image of each color is expanded so as not to exceed the threshold value.

[0003]

However, the above-mentioned prior art has the following problems. That is,
Since the threshold values are directly set for the basic color materials cyan (C), magenta (M), yellow (Y), and black (K), there is a problem that the gradation of the image is deteriorated. It was Further, in a mixed image of a character portion and a natural image portion, there is a problem that an edge is lowered in the character portion and gradation is lowered in the natural image portion.
In addition, since the density adjustment is performed so that the entire cyan (C), magenta (M), yellow (Y), and black (K) are within the threshold, there is a problem that it takes time to develop the image. It was

The present invention has been made in view of the above-mentioned points, and it is possible to enhance the gradation of an image without degrading the edge of a character portion without degrading the gradation of an image. An object of the present invention is to provide an image processing apparatus, an image processing method, a print processing system, a print processing method, and a storage medium that are capable of performing high-quality image output and high-speed image development.

[0005]

According to the first aspect of the present invention,
In an image processing apparatus in which the total amount of coloring material per pixel is limited due to the image forming process, C (cyan), M
(Magenta), Y (yellow), K (black) image scanning means for scanning the entire image after developing bitmap images for four surfaces, and a threshold value set in advance for the image scanned by the image scanning means Determining means for determining whether or not there is a portion exceeding the threshold, and a color for performing color space conversion on the bitmap image when the determining means determines that there is a portion exceeding the threshold value. The space conversion means and the conversion color for adjusting the color density of the image so that the maximum value exceeding the threshold value of the bitmap image converted by the color space conversion means becomes the maximum value within the threshold value. And a space adjusting means.

According to a second aspect of the present invention, in an image processing apparatus in which the total amount of coloring material per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) and K (black) image scanning means for scanning the entire image after developing bitmap images for four surfaces, and detection for detecting character portions and natural image portions in the image scanned by the image scanning means Means, a direct density adjusting means for adjusting the color density of the image of the character portion detected by the detecting means, and a color space conversion for converting the color space of the image of the natural image portion detected by the detecting means. And a conversion color space adjusting unit for adjusting the color density of the image of the natural image part converted by the color space converting unit.

According to a third aspect of the present invention, in an image processing apparatus in which the total amount of coloring material per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) Image scanning means for scanning the entire image after expanding the bitmap images for three planes, and storage means for storing the color densities of the three C, M, and Y colors for the image scanned by the image scanning means. , Comparing the color density stored in the storage means with a preset threshold value at the time of developing the K (black) surface, and comparing the entire C, M, Y, K4 surfaces based on the comparison result by the comparing means. And a direct adjusting means for adjusting the color density of the K plane so that the color density falls within the threshold value.

According to a fourth aspect of the present invention, there is provided a print processing system including the image processing apparatus according to the first, second or third aspect.

According to a fifth aspect of the present invention, in an image processing method in which the total amount of color materials per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) and K (black) There are an image scanning step of scanning the entire image after developing the bitmap images for four surfaces, and a portion exceeding a preset threshold for the image scanned in the image scanning step. A determination step of determining whether or not there is a color space conversion step of performing color space conversion on the bitmap image when determining that there is a portion exceeding the threshold value in the determination step; And a conversion color space adjusting step for adjusting the color density of the image so that the maximum value of the bitmap images converted in the spatial conversion step exceeds the threshold value. Is characterized by.

According to a sixth aspect of the present invention, in an image processing method in which the total amount of color materials per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow), K (black) An image scanning step of scanning the entire image after developing the bitmap images for four surfaces, and a detection step of detecting a character portion and a natural image portion in the image scanned in the image scanning step. A direct density adjusting step of adjusting color density of the image of the character portion detected in the detecting step, and a color space converting step of converting a color space of the image of the natural image portion detected in the detecting step. And a conversion color space adjusting step for adjusting the color density of the image of the natural image portion converted in the color space converting step.

According to a seventh aspect of the present invention, in an image processing method in which the total amount of color materials per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) An image scanning step of scanning the entire image after developing the bitmap images for three planes, a storage step of storing color densities of all C, M, and Y colors of the image scanned in the image scanning step, A comparison step of comparing the color density stored in the storage step with a preset threshold value at the time of developing the K (black) surface, and the colors of the entire C, M, Y, and K surfaces based on the comparison result in the comparison step. And a direct adjustment step of adjusting the color density of the K plane so that the density falls within the threshold value.

The invention according to claim 8 is the print processing method, wherein the image processing method according to claim 5, 6 or 7 is used.

The present invention is used in an image processing apparatus in which the total amount of color materials per pixel is limited due to the image forming process, and is described in a predetermined language format that can be interpreted by the image processing apparatus. Scanning program module that scans the entire image after developing a bitmap image for four planes of C (cyan), M (magenta), Y (yellow), and K (black) in a storage medium that stores the created program And a determination program module for determining whether or not there is a portion exceeding a preset threshold value in the scanned image, and a bitmap image when it is determined that there is a portion exceeding the threshold value. A color space conversion program module that performs color space conversion for
A converted color space adjusting program module for adjusting the color density of the converted bitmap image so that the maximum value of the values exceeding the threshold value becomes the maximum value within the threshold value. And

The invention described in claim 10 is used in an image processing apparatus in which the total amount of color materials per pixel is limited in the image forming process, and is described in a predetermined language format that can be interpreted by the image processing apparatus. In the storage medium storing the selected program, C (cyan), M (magenta), Y
An image scanning program module that scans the entire image after developing bitmap images for four (yellow) and K (black) planes; a detection program module that detects a character portion and a natural image portion in the scanned image; A direct density adjustment program module for adjusting the color density of the detected image of the character portion, a color space conversion program module for converting the color space of the detected image of the natural image portion, and the converted natural image And a conversion color space adjustment program module for adjusting the color density of the partial image.

The invention described in claim 11 is used in an image processing apparatus in which the total amount of color materials per pixel is limited in the image forming process, and is described in a predetermined language format that can be interpreted by the image processing apparatus. In the storage medium storing the selected program, C (cyan), M (magenta), Y
(Yellow) An image scanning program module that scans the entire image after developing the bitmap images for three planes,
A storage program module that stores the color densities of all three colors of C, M, and Y for the scanned image, and a comparison program module that compares the stored color density with a preset threshold value when developing the K plane (black). And a direct adjustment program module that adjusts the color density of the K surface so that the color density of the entire C, M, Y, and K surfaces falls within the threshold value based on the comparison result.

[0016]

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

(1) First Embodiment First, the configuration of a laser beam printer as a printing apparatus according to the first embodiment will be described with reference to FIG. A laser beam printer (hereinafter abbreviated as LBP) is connected to a host computer (see FIG. 1) to form a printing system, and a character source is registered by a data source (not shown) and a fixed form (form data) is formed. It is configured to be able to register. The printing device is not limited to the laser beam printer, and a printer of another type such as an inkjet printer may be used.

The laser beam printer includes an LBP main body 10
00, laser driver 1001, and semiconductor laser 10
02, a rotating polygon mirror 1004, and an electrostatic drum 1005.
Developing unit 1006 and paper cassette 1007
A paper feed roller 1008, and transport rollers 1009, 10
10, a printer controller 1100, and an operation panel 1200.

The LBP body 1000 includes a laser driver 1001 and a semiconductor laser 1 in detail.
002, a rotary polygon mirror 1004, an electrostatic drum 1005, a developing unit 1006, a paper cassette 1007, a paper feed roller 1008, conveyance rollers 1009 and 1010, a printer controller 1100, and an operation panel 1200, which are connected to the outside. Host computer 300
Character information (character code) supplied from 0 (see FIG. 1)
Form information, macro commands, etc. are input and stored, and corresponding character patterns, form patterns, etc. are created in accordance with the information, and an image is formed on a recording paper as a recording medium.

The laser driver 1001 is a circuit for driving the semiconductor laser 1002, and switches ON / OFF of the laser beam 1003 emitted from the semiconductor laser 1002 according to the input video signal. Semiconductor laser 100
2 emits a laser beam 1003 toward the rotary polygon mirror 1004 based on the driving by the laser driver 1001.
The rotating polygon mirror 1004 swings the laser light 1003 emitted from the semiconductor laser 1002 in the left-right direction. The surface of the electrostatic drum 1005 is scanned by the laser beam 1003 reflected by the rotating polygon mirror 1004. This allows
An electrostatic latent image having a character pattern is formed on the surface of the electrostatic drum 1005.

The developing unit 1006 includes the electrostatic drum 10
No. 05 is arranged to develop the electrostatic latent image formed on the electrostatic drum 1005. After the electrostatic latent image is developed, it is transferred to recording paper. The paper cassette 1007 is mounted on the LBP main body 1000, and for example, cut sheet recording paper is stored inside the paper cassette 1007. Paper feed roller 1008
Takes in the cut sheet recording paper stored in the paper cassette 1007 one by one into the apparatus. Transport roller 10
Reference numerals 09 and 1010 convey and supply the cut sheet recording paper fed by the paper feed roller 1008 to the electrostatic drum 1005.

Next, the configuration of the printer control system of the printing system including the laser beam printer and the host computer according to the first embodiment will be described with reference to FIG. The host computer 3000 has a CPU 1 and a RAM 2
, ROM 3, system bus 4, keyboard controller (KBC) 5, CRT controller (CRT)
C) 6, disk controller (MC) 7, network interface circuit (NW I / F) 8, keyboard (KB) 9, and CRT display (CRT) 1
0 and the external memory 11 are provided.

The laser beam printer has a CPU 1
2, RAM 19, ROM 13, and system bus 15
And network interface circuit (NW I / F)
18, a printing unit interface (I / F) 16, a disk controller (MC) 20, a printing unit (printer engine) 17, an operation panel 1200, and an external memory 1.
4 is provided.

The configuration of each section of the host computer 3000 will be described in detail. The CPU 1 uses the graphics, images, characters, and
The processing of a document in which tables (including spreadsheets and the like) are mixed is executed, and each device connected to the system bus 4 is comprehensively controlled. Further, the CPU 1 executes outline font rasterization processing for the display information RAM set on the RAM 2, and the CRT display 1
0 on WYSIWYG (What You See Is What
You Get: A function that enables printing as it is on the screen). Further, the CPU 1 opens various windows registered on the CRT display 10 according to a command designated by a mouse cursor (not shown) or the like, and executes various data processing.

The RAM 2 functions as a main memory, a work area, etc. of the CPU 1. ROM3 is a font RO
M3a, program ROM 3b, data ROM
It has a storage area divided into 3c. R for font
The OM 3a stores font data and the like used in the above document processing, and the program ROM 3b stores a document processing program to be described later, and the data ROM 3
In c, various data used when performing the document processing and the like are stored.

The keyboard controller (KBC) 5 is
It controls key input from a keyboard (KB) 9 or a pointing device (not shown). A CRT controller (CRTC) 6 controls the display on the CRT display 10. The disk controller (MC) 7 controls access to the external memory 11. The network interface circuit (NW I / F) 8 is connected to another host computer or the LBP main body 10 via a predetermined network 21.
00 to control communication with other devices such as the LBP main body 1000.

The keyboard (KB) 9 has various keys for the user to input various data and the like. CRT
The display (CRT) 10 displays figures, characters, tables and the like. The external memory 11 is configured as a hard disk (HD), a floppy disk (FD), etc. that stores a boot program, various application programs, font data, user files, edit files and the like.

The configuration of the laser beam printer will be described in detail. The CPU 12 is a program ROM of the ROM 13.
Control program or external memory 1 stored in 13b
4 controls the access to various devices connected to the system bus 15 on the basis of the control program stored in the printer 4 and is connected via a printer interface (I / F) 16 to a printer (printer engine). ) 17 to output an image signal as output information. Further, the CPU 12 can perform communication processing with the host computer 3000 and other printers via the network interface circuit (NW I / F) 8, and can notify the host computer 3000 of information and resource data in the printer. Has become.

As shown in FIG. 6, the program ROM 13b of the ROM 13 stores a plurality of program modules (hereinafter referred to as modules) executed by the CPU 12, and each module includes C (cyan) and M (magenta). ), Y (yellow), and K (black) image scanning modules 601 for scanning the entire image after developing the bitmap images for four surfaces, and there is a portion that exceeds a preset threshold value for the scanned image. A determination module 602 for determining whether or not there is a portion, a color space conversion module 603 for performing color space conversion on the bitmap image when it is determined that there is a portion exceeding the threshold value, and the converted bit For the map image, the maximum value that exceeds the threshold is set to the maximum value within the threshold. There is a transformation color space adjustment module 604 for adjusting the concentration. By executing each of these modules, the processing shown in the flowchart of FIG. 3 is executed.

The RAM 2 functions as a main memory, a work area, etc. of the CPU 1, and the memory capacity can be expanded by an optional RAM connected to an expansion port (not shown). The RAM 19 includes an output information expansion area, an environment data storage area, and a non-volatile RAM (NVR).
AM) etc. ROM13 is a font RO
M13a, program ROM 13b, data R
It has a storage area divided into the OM 13c. The font ROM 3a stores font data and the like used when the output information is generated, and is a program ROM.
A control program to be described later is stored in 13b, and an external memory 1 such as a hard disk is stored in the data ROM 3c.
If the printer does not have 4, the host computer 30
The information and the like used on the 00 are stored.

Network interface circuit (NW
The I / F 18 is connected to the host computer 3000 via a predetermined network 21 and controls communication with the host computer 3000. The printing unit interface (I / F) 16 sends and receives signals between the CPU 12 and the printing unit (printer engine) 17. The disk controller (MC) 20 controls access to the external memory 14.

The printing unit (printer engine) 17 is a CP
The printing operation is performed based on the image signal output from U12. The operation panel 1200 includes operation switches, a display unit (for example, an LED display device), and the like. External memory 1
Reference numeral 4 is configured as a hard disk (HD), an IC card, etc., access is controlled by the disk controller (MC) 20 and is connected as an option, and stores font data, emulation program, form data and the like.

The above-mentioned external memory 14 is not limited to one, but a plurality of external memories 14 may be provided. In addition to the built-in font, an optional font card and an external memory storing a program for interpreting a printer control language of a different language system. It may be configured to be able to connect a plurality of. In addition, external memory 1
The operation panel 120 includes an NVRAM (not shown).
The printer mode setting information from 0 may be stored.

Next, in the printing system including the laser beam printer and the host computer according to the first embodiment configured as described above, the process of limiting the total amount of the coloring material per pixel is shown in the flowchart of FIG. It will be explained based on. In FIG. 3, after the images for four planes of cyan (C), magenta (M), yellow (Y), and black (K) are developed, color space conversion is performed, and color density correction is performed in the converted color space. It is a flow chart which shows the processing procedure which performs.

First, the print data input from the host computer 3000 is developed into a bitmap image for each color component (step S101). Similarly, the development processing into the bitmap image is repeated for all the color components of the four surfaces of cyan (C), magenta (M), yellow (Y), and black (K) (step S102). Next, 4
Scan the bitmap image of the area. here,
In each of the four bitmap images, the pixel values at the same pixel position are accumulated for four surfaces (step S10).
3).

Next, the pixel value P accumulated in step S103 is compared with a preset threshold value T (step S104). When the pixel value P is larger than the threshold value T, the value and position of the pixel value P are temporarily stored. Next, when a pixel value P ′ larger than the threshold value T appears, the pixel value P and the pixel value P ′ are compared, and the larger one is stored as P. When the comparison between the pixel value and the threshold value for the entire bitmap image is completed, the color space of the image is converted (step S10).
5). After that, the CMYK color space is converted into a YUV color space which is information on luminance and color.

Next, in the bitmap of the converted color space, the color density of the entire bitmap image is adjusted based on the value of the color information UV at the position of the stored pixel value P (step S106). When adjusting the color density, the color information UV at the position of the stored pixel value P is shifted to the maximum value that the pixel can take, and the color information at other positions is also shifted so as to be proportional to the difference from the pixel value P. . When the shift of the color information is completed for the entire bitmap image, the inverse conversion of the image color space is performed (step S107).

As described above, according to the first embodiment, the printing system uses C (cyan), M (magenta),
After the Y (yellow) and K (black) four-sided bitmap images are developed, the entire image is scanned and it is determined whether or not there is a portion of the scanned image that exceeds a preset threshold value. , If it is determined that there is a part that exceeds the threshold value, color space conversion is performed on the bitmap image, and the maximum value of the values exceeding the threshold value for the converted bitmap image is within the threshold value. Since the color density of the image is adjusted to be the maximum value of, the high-quality output can be performed without degrading the gradation of the image even when the total amount of the color material per pixel is limited.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. .

That is, in the present embodiment, the ROM 13b is used as a storage medium for storing each program module for realizing the present invention, and the present invention is realized by the CPU reading and executing each program module from the ROM 13b. In addition, the ROM 13b storing each program module constitutes the present invention.

As a storage medium replacing the ROM 13b, for example, a floppy disk, a hard disk,
Optical disc, magneto-optical disc, CD-ROM, CD-
R, a magnetic tape, a nonvolatile memory card, or the like can be used.

(2) Second Embodiment A laser beam printer as a printing apparatus according to a second embodiment has an LBP main body 1000, a laser driver 1001 and a laser driver 1001 as in the first embodiment. Semiconductor laser 1002, rotating polygon mirror 1004, electrostatic drum 10
05, the developing unit 1006, and the paper cassette 100
7, paper feed roller 1008, and conveyance rollers 1009, 1
010, a printer controller 1100, and an operation panel 1200 (see FIG. 2 above).

The host computer 3000 constituting the printing system according to the second embodiment is the above-mentioned first computer.
Similar to the embodiment described above, the CPU 1, the RAM 2, and the RO
M3, system bus 4, keyboard controller (KBC) 5, CRT controller (CRTC) 6
A disk controller (MC) 7, a network interface circuit (NW I / F) 8, a keyboard (KB) 9, a CRT display (CRT) 10,
And an external memory 11 (see FIG. 1 above).

The laser beam printer constituting the printing system according to the second embodiment has a CPU 12, a RAM 19, and a ROM, as in the first embodiment.
13, a system bus 15, a network interface circuit (NW I / F) 18, a printing unit interface (I / F) 16, and a disk controller (MC) 2
0, a printing unit (printer engine) 17, an operation panel 1200, and an external memory 14 (see FIG. 1 above).
reference). The detailed configuration of each of the above-described units has been described in detail in the first embodiment, and thus description thereof will be omitted.

In the first embodiment, the color space is converted for the entire developed bitmap image, but in the second embodiment, the image area is divided into the natural image portion and the character portion. The feature is that the color space is converted only for the natural image portion. Specifically, as shown in FIG. 7, the ROM 31b scans the entire image after developing the bitmap images for four C (cyan), M (magenta), Y (yellow), and K (black) planes. An image scanning module 701, a detection module 702 that detects a character portion and a natural image portion in the scanned image, a direct density adjustment module 703 that adjusts color density for the image of the detected character portion, and a detected natural image portion. A color space conversion module 704 that converts the color space of the partial image, and a conversion color space adjustment module 7 that adjusts the color density of the converted image of the natural image portion.
05 is stored, and the CPU reads and executes each module to execute the processing shown in the flowchart of FIG. 4 described later.

Next, the processing of the printing system including the laser beam printer and the host computer according to the second embodiment configured as described above will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing a processing procedure for performing color space conversion by performing area division of an image and correcting color density.

First, the print data input from the host computer 3000 is developed into a bitmap image for each color component (step S101). Similarly, the development processing into the bitmap image is repeated for all the color components of the four surfaces of cyan (C), magenta (M), yellow (Y), and black (K) (step S102). Next, 4
Scan the bitmap image of the area. here,
In each of the four bitmap images, the pixel values at the same pixel position are accumulated for four surfaces (step S10).
3). That is, similarly to the first embodiment, the print data from the host computer 3000 is developed into a bitmap image in steps S101 to S103.

Next, the bitmap image of four planes of cyan (C), magenta (M), yellow (Y), and black (K) is divided into blocks for every several pixels, and the blocks are detected by edge detection or the like so that the blocks are displayed in the natural image portion. And the character part (steps S201 and 202).

In the natural image portion (the determination in step S202 is positive), the pixel value P accumulated in step S103 is compared with the preset threshold value T (step S104). When the pixel value P is larger than the threshold value T, the value and position of the pixel value P are temporarily stored. Next, when a pixel value P ′ larger than the threshold value T appears, the pixel value P and the pixel value P ′ are compared, and the larger one is stored as P. When the comparison between the pixel value and the threshold value is completed for the entire bitmap image, the color space of the image is converted (step S105).
After that, the CMYK color space is converted to YUV which is information on luminance and color.
Convert to color space.

Next, the color density of the entire bitmap image is adjusted based on the value of the color information UV at the position of the pixel value P stored in the converted bitmap of the color space (step S106). When adjusting the color density, the color information UV at the position of the stored pixel value P is shifted to the maximum value that the pixel can take, and the color information at other positions is also shifted so as to be proportional to the difference from the pixel value P. . When the shift of the color information is completed for the entire bitmap image, the inverse conversion of the image color space is performed (step S107).

That is, in the natural image portion, similarly to the first embodiment, the pixel value is compared with the threshold value, the color space is converted, and then the color density is corrected.

On the other hand, in the character portion (step S20 above)
When the determination of 2 is negative), the pixel value P accumulated in step S103 is compared with a preset threshold value T (step S104). When the pixel value P is larger than the threshold value T, the value and position of the pixel value P are temporarily stored.

Next, in the bitmap of the character part,
The values of the stored color information CMYK at the position of the pixel value P are directly changed to adjust the color density (step S
106).

That is, in the character portion, after the pixel value is compared with the threshold value, the pixel value is directly corrected.

As described above, according to the second embodiment, the printing system uses C (cyan), M (magenta),
After the Y (yellow) and K (black) four-sided bitmap images are developed, the entire image is scanned, the character portion and the natural image portion are detected in the scanned image, and the detected character portion image is detected. The color density is adjusted, the color space is converted to the detected image of the natural image portion, and the color density is adjusted to the converted image of the natural image portion. In addition, it is possible to perform high-quality output without degrading the gradation of the natural image portion.

(3) Third Embodiment A laser beam printer as a printing apparatus according to a third embodiment is similar to the first and second embodiments described above.
LBP main body 1000, laser driver 1001, semiconductor laser 1002, rotating polygon mirror 1004, electrostatic drum 1005, developing unit 1006, paper cassette 1007, paper feed roller 1008, and conveyance roller 10.
09, 1010, the printer controller 1100,
And an operation panel 1200 (see FIG. 2 above).

The host computer 3000 constituting the printing system according to the third embodiment is the first computer
And, similarly to the second embodiment, the CPU 1 and the RAM 2
, ROM 3, system bus 4, keyboard controller (KBC) 5, CRT controller (CRT)
C) 6, disk controller (MC) 7, network interface circuit (NW I / F) 8, keyboard (KB) 9, and CRT display (CRT) 1
0 and an external memory 11 (see FIG. 1 above).

The laser beam printer constituting the printing system according to the third embodiment has a CPU 12 and a RAM 19 as in the first and second embodiments.
A ROM 13, a system bus 15, a network interface circuit (NW I / F) 18, a printing unit interface (I / F) 16, a disk controller (MC) 20, a printing unit (printer engine) 17,
An operation panel 1200 and an external memory 14 are provided (see FIG. 1 above). The detailed configuration of each of the above-described units has been described in detail in the first embodiment, and thus description thereof will be omitted.

In the first and second embodiments, all the colors are displayed after the development of the four cyan (C), magenta (M), yellow (Y), and black (K) planes into a bitmap is completed. Although the color density is corrected, the third embodiment is characterized in that the color density is corrected only on the K plane after the development of the CMY3 plane into the bitmap is completed. Specifically, in the ROM 31b, as shown in FIG. 8, an image scanning module 801 that scans the entire image after developing the bitmap images for the three planes C, M, and Y, and C, M, and Y3 for the scanned image. A storage module 802 that stores the color density of all colors, a comparison module 803 that compares the stored color density with a preset threshold value when developing the K plane, and C, M, Y, and K planes based on the comparison result. A direct adjustment module 804 that adjusts the color density of the K plane so that the overall color density falls within the threshold value is stored, and each module is read out and executed by the CPU, which is shown in the flowchart of FIG. 5 described later. The process is executed.

Next, the processing of the printing system including the laser beam printer and the host computer according to the third embodiment configured as described above will be described with reference to the flowchart of FIG. FIG. 5 is a flowchart showing a processing procedure for correcting the color density only on the K plane.

First, the print data input from the host computer 3000 is developed into a bitmap image for each color component (step S101). Similarly, the expansion processing into the bitmap image is repeated for the three color components of cyan (C), magenta (M), and yellow (Y) (step S301). Next, the bitmap images for three surfaces are scanned (step S103). here,
Pixel values at the same pixel position are accumulated for three surfaces in the bitmap images of each of the three surfaces (step S30).
2).

Next, the K-side bitmap image is developed (step S303). At this time, the result of accumulating the pixel values of the K plane expanded to the pixel value accumulated in step S302 is compared with a preset threshold value. If the pixel value accumulated for four surfaces is larger than the threshold value, the pixel value for the K surface is directly corrected.

As described above, according to the third embodiment, the printing system scans the entire image after expanding the bitmap images for C, M, and Y3 planes, and C for the scanned image, The color densities of all the three colors M and Y are stored and stored, and the stored color density and a preset threshold value are stored as K.
Compared when the surface is developed, and based on the comparison result, C, M, Y, K
It has a direct adjustment function that adjusts the color density of the K plane so that the color density of all four planes falls within the threshold, so that even when the total amount of color material per pixel is limited, image development can be performed at high speed. Can be done.

[0064]

As described above, according to the first aspect of the invention, in the image processing apparatus in which the total amount of the coloring material per pixel is limited due to the image forming process, C (cyan), M ( An image scanning unit that scans the entire image after developing bitmap images for four surfaces of magenta), Y (yellow), and K (black), and a threshold value set in advance for the image scanned by the image scanning unit. Determination means for determining whether or not there is a portion that exceeds the threshold, and a color space for performing color space conversion on the bitmap image when the determination means determines that there is a portion that exceeds the threshold value A conversion unit and a conversion color space that adjusts the color density of the image so that the maximum value of the bitmap images converted by the color space conversion unit exceeds the threshold value. To and a regulating means, even when there is a limit to the total amount of colorant per pixel, it is possible to perform high-quality output without lowering the gradation of the image, an effect that.

According to the second aspect of the invention, in the image processing apparatus in which the total amount of the color material per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) and K (black) image scanning means for scanning the entire image after developing bitmap images for four surfaces, and detection for detecting character portions and natural image portions in the image scanned by the image scanning means Means, a direct density adjusting means for adjusting the color density of the image of the character portion detected by the detecting means, and a color space conversion for converting the color space of the image of the natural image portion detected by the detecting means. And a conversion color space adjusting unit that adjusts the color density of the image of the natural image part converted by the color space converting unit. Therefore, it is possible to perform high-quality output without degrading the gradation of the natural image portion.

According to the third aspect of the invention, in the image processing apparatus in which the total amount of the color material per pixel is limited due to the image forming process, C (cyan), M (magenta), Y
(Yellow) Image scanning means for scanning the entire image after expanding the bitmap images for three planes, and storage means for storing the color densities of the three C, M, and Y colors for the image scanned by the image scanning means. , Comparing the color density stored in the storage means with a preset threshold value at the time of developing the K (black) surface, and comparing the entire C, M, Y, K4 surfaces based on the comparison result by the comparing means. Since the direct adjustment means for adjusting the color density of the K surface so as to keep the color density within the threshold value is provided, the image development can be performed at high speed even when the total amount of the color material per pixel is limited. The effect is that it can be performed.

According to the invention of claim 4, since the print processing system has the image processing device according to claim 1, 2 or 3, when the print processing by this print processing system is performed,
Even if there is a limit to the total amount of colorant per pixel,
It is possible to perform high-quality printing without degrading the gradation of the image, or it is possible to suppress edge deterioration etc. in the character part, and high-quality printing without degrading the gradation of the natural image part. It is possible to perform the above, or even when the total amount of the color material per pixel is limited, the image development can be performed at high speed.

According to the fifth aspect of the present invention, in the image processing method in which the total amount of color material per pixel is limited in the image forming process, C (cyan), M (magenta), Y
(Yellow) and K (black) There are an image scanning step of scanning the entire image after developing the bitmap images for four surfaces, and a portion exceeding a preset threshold for the image scanned in the image scanning step. A determination step of determining whether or not there is a color space conversion step of performing color space conversion on the bitmap image when determining that there is a portion exceeding the threshold value in the determination step; A bitmap color image converted in the spatial conversion step, and a conversion color space adjustment step of adjusting the color density of the image so that the maximum value of the values exceeding the threshold value becomes the maximum value within the threshold value. Even when the total amount of color material per pixel is limited, it is possible to perform high-quality output without degrading the gradation of the image.

According to the sixth aspect of the present invention, in the image processing method in which the total amount of color materials per pixel is limited in the image forming process, C (cyan), M (magenta), Y
(Yellow), K (black) An image scanning step of scanning the entire image after developing the bitmap images for four surfaces, and a detection step of detecting a character portion and a natural image portion in the image scanned in the image scanning step. A direct density adjusting step of adjusting color density of the image of the character portion detected in the detecting step, and a color space converting step of converting a color space of the image of the natural image portion detected in the detecting step. , And a conversion color space adjusting step of adjusting color density for the image of the natural image portion converted in the color space converting step, it is possible to suppress edge deterioration and the like in the character portion and High-quality output can be performed without degrading gradation.
This has the effect.

According to the invention of claim 7, in the image processing method in which the total amount of the coloring material per pixel is limited in the image forming process, C (cyan), M (magenta), Y
(Yellow) An image scanning step of scanning the entire image after developing the bitmap images for three planes, a storage step of storing color densities of all C, M, and Y colors of the image scanned in the image scanning step, A comparison step of comparing the color density stored in the storage step with a preset threshold value at the time of developing the K (black) surface, and the colors of the entire C, M, Y, and K surfaces based on the comparison result in the comparison step. Since there is a direct adjustment step of adjusting the color density of the K surface so that the density falls within the threshold value, the image development can be performed at high speed even when the total amount of the color material per pixel is limited. There is an effect that it can.

According to the eighth aspect of the present invention, the print processing method uses the image processing method according to the fifth, sixth or seventh aspect. Even when the total amount is limited, it is possible to perform high-quality printing without degrading the gradation of the image, or it is possible to suppress the edge deterioration in the character portion and the gradation of the natural image portion. There is an effect that high-quality printing can be performed without deteriorating the property, or even when the total amount of color materials per pixel is limited, image development can be performed at high speed.

According to the invention described in claim 9, a predetermined language format which can be used by an image processing apparatus in which the total amount of coloring materials per pixel is limited in the image forming process and which can be interpreted by the image processing apparatus. In the storage medium storing the program described in, C (cyan), M (magenta),
An image scanning program module that scans the entire image after developing the Y (yellow) and K (black) four-sided bitmap images, and whether there is a portion of the scanned image that exceeds a preset threshold value. A determination program module for determining whether or not there is a portion exceeding the threshold value, a color space conversion program module for performing color space conversion on the bitmap image, and the converted bitmap image With respect to each of the modules, the conversion color space adjusting program module for adjusting the color density of the image so that the maximum value exceeding the threshold value becomes the maximum value within the threshold value. Even if the total amount of color material per pixel is limited, high-quality output can be performed without reducing the gradation of the image. Can, an effect that.

According to the tenth aspect of the present invention, a predetermined language format which can be used by an image processing apparatus in which the total amount of color materials per pixel is limited due to the image forming process and which can be interpreted by the image processing apparatus. Image scanning for scanning the entire image after developing a bitmap image for four planes of C (cyan), M (magenta), Y (yellow), and K (black) in a storage medium storing the program described in A program module, a detection program module that detects a character portion and a natural image portion in the scanned image, a direct density adjustment program module that adjusts color density for the image of the detected character portion, and the detected natural portion A color space conversion program module for converting the color space of the image of the image portion, and a color for the converted image of the natural image portion. Since it has a conversion color space adjusting program module for adjusting the degree, by executing each module in the image processing apparatus, it is possible to suppress the edge deterioration in the character portion and to reduce the gradation of the natural image portion. The effect is that high-quality output can be performed without having to do so.

According to the eleventh aspect of the present invention, a predetermined language format which can be used by an image processing apparatus in which the total amount of coloring materials per pixel is limited due to the image forming process and which can be interpreted by the image processing apparatus. An image scanning program module that scans the entire image after developing a bitmap image for three C (cyan), M (magenta), and Y (yellow) planes in a storage medium that stores the program described in A storage program module that stores the color densities of all three colors of C, M, and Y for the scanned image; and a comparison program module that compares the stored color density with a preset threshold value when developing the K plane (black),
A direct adjustment program module that adjusts the color density of the K plane so that the color density of the entire C, M, Y, and K planes falls within the threshold value based on the comparison result. By executing the above, there is an effect that the image development can be performed at high speed even when the total amount of the color material per pixel is limited.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a printer control system including a host computer and a laser beam printer according to first to third embodiments of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of the laser beam printer according to the first to third embodiments of the present invention.

FIG. 3 is a flowchart showing a processing procedure for performing color density correction in a converted color space according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure for performing color space conversion and color density correction after performing image area division according to the second embodiment of the present invention.

FIG. 5 is a flowchart showing a processing procedure for performing color density correction only on the K plane according to the third embodiment of the present invention.

FIG. 6 is a diagram showing an example of a memory map of a ROM according to the first embodiment of the invention.

FIG. 7 is a diagram showing an example of a memory map of a ROM according to a second embodiment of the present invention.

FIG. 8 is a diagram showing an example of a memory map of a ROM according to a third embodiment of the present invention.

[Explanation of symbols]

 1 CPU 12 CPU 17 Printing Unit 21 Network 31 ROM 1000 Laser Beam Printer 1200 Operation Panel 3000 Host Computer

Claims (11)

[Claims] 1. In an image processing apparatus in which the total amount of color material per pixel is limited in the image forming process, C (cyan), M (magenta), Y (yellow), K
(Black) Image scanning means for scanning the entire image after developing the bitmap images for four surfaces, and whether or not there is a portion exceeding the preset threshold value for the image scanned by the image scanning means Determining means, a color space converting means for converting the color space of the bitmap image when the determining means determines that there is a portion exceeding the threshold value, and the color space converting means. And a conversion color space adjusting unit that adjusts the color density of the image so that the maximum value of the values of the bitmap image converted by the above becomes the maximum value within the threshold value. Image processing device. 2. In an image processing apparatus in which the total amount of color materials per pixel is limited due to the image forming process, C (cyan), M (magenta), Y (yellow), K
(Black) Image scanning means for scanning the entire image after developing the bitmap images for four surfaces, detection means for detecting a character portion and a natural image portion in the image scanned by the image scanning means, and the detection Direct density adjusting means for adjusting the color density of the image of the character portion detected by the means, color space converting means for converting the color space of the image of the natural image portion detected by the detecting means, and the color An image processing apparatus comprising: a conversion color space adjusting unit for adjusting color density of an image of a natural image portion converted by the space converting unit. 3. An image processing apparatus in which the total amount of color materials per pixel is limited due to the image forming process, and bitmap images for three C (cyan), M (magenta), and Y (yellow) planes are displayed. An image scanning unit that scans the entire image after development, a storage unit that stores the color densities of the entire C, M, and Y colors of the image scanned by the image scanning unit, and the color densities stored in the storage unit in advance. Comparing means for comparing the set threshold value with each other when the K (black) surface is developed, and C, M, based on the comparison result by the comparing means.
An image processing apparatus comprising: a direct adjustment unit that adjusts the color density of the K surface so that the color density of the entire Y, K4 surface falls within the threshold value. 4. A print processing system comprising the image processing apparatus according to claim 1, 2, or 3. 5. In an image processing method in which the total amount of color materials per pixel is limited in the image forming process, C (cyan), M (magenta), Y (yellow), K
(Black) An image scanning step of scanning the entire image after developing the bitmap images for four surfaces, and determining whether or not there is a portion of the image scanned in the image scanning step that exceeds a preset threshold value A color space conversion step for performing color space conversion on the bitmap image when it is determined that there is a portion exceeding the threshold value in the judgment step, and conversion in the color space conversion step A bitmap image, the conversion color space adjusting step of adjusting the color density of the image so that the maximum value exceeding the threshold value becomes the maximum value within the threshold value. Processing method. 6. An image processing method in which the total amount of color materials per pixel is limited due to the image forming process, and C (cyan), M (magenta), Y (yellow), K
An image scanning step of scanning the entire image after developing the (black) four-sided bitmap image, a detection step of detecting a character portion and a natural image portion in the image scanned in the image scanning step, and a detection step. A direct density adjustment step for adjusting the color density of the detected character portion image; a color space conversion step for converting the color space of the natural image portion image detected in the detection step; And a conversion color space adjusting step for adjusting the color density of the image of the natural image portion converted in the step. 7. An image processing method in which the total amount of color materials per pixel is limited in the image forming process, wherein C (cyan), M (magenta), and Y (yellow) bitmap images for three planes are formed. An image scanning step of scanning the entire image after development, a storage step of storing the color densities of the entire C, M, and Y colors of the image scanned in the image scanning step, and a color density stored in the storage step are preset. A comparison step of comparing the threshold value with the K (black) surface when developing, and based on the comparison result in the comparison step, the color densities of the entire C, M, Y, and K4 surfaces are set within the threshold value And a direct adjustment step of adjusting the color density of the K plane. 8. A print processing method using the image processing method according to claim 5, 6, or 7. 9. A program, which is used in an image processing apparatus in which the total amount of color materials per pixel is limited in the image forming process and is described in a predetermined language format that can be interpreted by the image processing apparatus, is stored. C (cyan), M (magenta), Y (yellow), K
An image scanning program module that scans the entire image after developing (black) four-sided bitmap images,
A determination program module for determining whether or not there is a portion exceeding a preset threshold value in the scanned image, and for the bitmap image when it is determined that there is a portion exceeding the threshold value. And a color space conversion program module that performs color space conversion, and adjusts the color density of the image so that the maximum value of the converted bitmap images that exceeds the threshold value becomes the maximum value within the threshold value. A storage medium having a conversion color space adjustment program module for adjustment. 10. An image processing apparatus in which the total amount of coloring material per pixel is limited in the image forming process,
In a storage medium storing a program described in a predetermined language format that can be interpreted by the image processing apparatus, C (cyan), M (magenta), Y (yellow), K
An image scanning program module that scans the entire image after developing (black) four-sided bitmap images,
A detection program module that detects a character portion and a natural image portion in the scanned image, a direct density adjustment program module that adjusts color density for the detected character portion image, and an image of the detected natural image portion A storage medium, comprising: a color space conversion program module for performing color space conversion on a color space; and a conversion color space adjustment program module for adjusting color density of the converted natural image portion image. 11. An image processing apparatus in which the total amount of color materials per pixel is limited in the image forming process,
In a storage medium that stores a program described in a predetermined language format that can be interpreted by the image processing apparatus, after developing C (cyan), M (magenta), and Y (yellow) three-sided bitmap images An image scanning program module that scans the entire image, a storage program module that stores the color densities of all the C, M, and Y colors of the scanned image, and the stored color density and a preset threshold value on the K plane. A comparison program module to be compared when developing (black) and C based on the comparison result,
A storage medium having a direct adjustment program module for adjusting the color density of the K plane so that the color density of the entire M, Y, K planes falls within the threshold value.