JP2721347B2 - Image processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for processing an image, and more particularly to an image processing apparatus for outputting an image by a multi-value printer.

[Conventional technology]

An example of the configuration of the document image processing device will be described with reference to FIG. FIG. 17 shows the concept of a document / image combining process using the display shown in FIG.

CPU 201 is RAM 203 according to the firmware in ROM 202,
The entire device is controlled using the interrupt controller 204, the timer counter 205, and the like. The disk controller 217 controls a disk drive (not shown) to perform read / write operations on the floppy disk 218 and the hard disk 219. These disks store an OS, application programs, and data files composed of images and characters.

A keyboard 208 and a point device 209 as instruction means from an operator are connected via the I / O port 206. Other external devices 207 are also connected via the I / O port 206. The I / O port 206 includes a communication port such as RS232C or SCSi. CRT controller 211 is memory for display
The contents of VRAM 213 are displayed on CRT 210.

The scanner / printer interface 220 captures an image from the scanner 221 based on a command from the CPU 201,
The image is sent to the printer 222 and printed. The image memories 232 and 233 are bit map memories for storing images taken from the scanner 221 and images to be printed on the printer 222. In the text memory 230, a document file created on the CRT 210 by the operator using the keyboard 208 or the point device 209 (hereinafter referred to as a text file)
Is stored in a code corresponding to the character, and the graphic memory 231 stores graphic information (hereinafter, a graphic file) similarly created on the CRT 210.
The graphic information is stored as a bit image or vector information corresponding to the display pixel of the CRT 210. The text file and the graphic file are usually stored on the floppy disk 218 and the hard disk 219 described above, but are called by the text memory 230 and the graphic memory 231 when edited on the CRT 210.

The code image conversion unit 252 converts each code of the text file on the text memory 230 into a bit image while referring to the font ROM 212 and develops it into the VRAM 213. The graphic processing unit 251 converts the bit image of the To the VRAM 213 using vector data, or in the case of vector information, convert the vector information into a bit
Expand to 3. Furthermore, the natural image processing unit 250
The image of the original read in step (1) is normally reduced from the image memory 232 and transferred to the VRAM 213. Conversion unit 252, processing units 250, 251
Are controlled by the CPU 201, but may have a dedicated CPU for speeding up, or may be controlled by the CRT controller 211.

Screen configuration information such as which part of each file of the text, graphic and image is arranged in the VRAM 213 is tabulated in the RAM 203.

The operator looks at the information displayed on the CRT 210 in this manner, and operates the keyboard 208 and the pointing device 209.
To create a screen that combines text, graphics, and images. During the editing process, the above-described screen configuration information table 254 in the RAM 203 is sequentially rewritten.

When the editing is completed and a print request is issued, the CPU 201 sets the image memory 2 based on the screen configuration information table 254.
33, necessary information from the text memory 230, the graphic memory 231 and the image memory 232 is developed as a bit image in accordance with the coordinate system of the printer.
The image data is sent to the printer 222 via the printer interface 220, and is printed by combining characters, graphics, and a document image.

The image memory 233 may be, for example, a full page memory capable of holding all print bit images for one sheet of paper, or a partial buffer memory if the speed of developing the image memory 233 is sufficient. Further, the natural image processing section 250 extracts a desired portion of the document image information from the image memory 232, and performs processes such as rotation, mirror image, and light / dark inversion in addition to enlargement and reduction.

In the example of FIG. 17, the image memories 232 and 233 are A4 size, 4
It has a capacity of 2 Mbytes so that it can read and print 00 dots per inch. The CRT210 is assumed to be 640 dots x 480 dots in monochrome, so it is the smallest
38K bytes are required. The graphic memory 231 also has a size of 38 Kbytes as a bit image, and the text memory 230 has a display of 40 digits × 25 lines. If the character code is 2 bytes, it is about 2 Kbytes.

Further, at the time of development to the image memory 233, the contents of the VRAM 213 may be directly transferred through the conversion unit 253 from the CRT coordinate system to the printer coordinate system.

[Problems to be solved by the invention]

Document image information and a document in the above-described 16th illustrated apparatus,
The synthesis of figures and the like is intended for binary image signals. That is, when the original is a halftone image such as a photograph, halftone expression is performed in the scanner 221 by pseudo halftone processing such as dithering.

In recent years, however, printers capable of multi-value recording have appeared, as seen in halftone reproduction using PWM control of the laser lighting time of a laser beam printer. These printers record document information that requires resolution,
It has two printing modes for printing a halftone image that requires gradation.

Therefore, in such a multi-value printer, it is necessary to switch the operation of the drive circuit and the like in accordance with the character information and the halftone information.

As described above, the control of the multi-valued printer is different from that of the binary printer. To use the multi-valued printer in the document image processing apparatus shown in FIG. However, it is impossible to obtain an optimal print output corresponding to a halftone image.

[Means for solving the problem]

The present invention has been made in view of the above points, and is an image processing apparatus for an apparatus that expands input multi-valued image data and forms an image based on the expanded multi-valued image data, The image storage means in which the multi-valued image data is expanded, and the recording density of each part of the image when forming the expanded multi-valued image data in correspondence with the multi-valued image data expanded in the image storage means. Recording density storage means for storing screen data to be displayed, a first pulse width modulation signal generated by comparing the multi-valued image data developed in the image storage means with a first pattern signal of a predetermined period, and A second pulse width modulation signal generated by comparing with a second pattern signal having a cycle different from that of the first pattern signal is selectively output according to screen data stored in the recording density storage means. Do Pulse width modulation means, and supplies the multi-valued image data developed in the image storage means and the screen data stored in the recording density storage means to the pulse width modulation means in synchronization with an image forming operation To provide an image processing apparatus.

〔Example〕

 Hereinafter, the present invention will be described using preferred embodiments.

FIG. 1 shows a configuration of an embodiment of a gradation image editing and recording apparatus using the present invention.

Reference numeral 121 denotes a color scanner, which color-separates a color original image line by line and photoelectrically reads it, and outputs color separation signals of three colors R, G, and B as image data consisting of 8-bit digital multivalued signals. Reference numeral 122 denotes a color printer which records an image line by line by raster scanning of a laser beam, and stores yellow (Y),
Based on the multi-valued image signal for each recording toner color of magenta (M), cyan (C), and black (K), each color image of Y, M, C, and K is formed by an electrophotographic process for each color. , And overlay them to produce a color hardcopy.

Reference numeral 120 denotes an interface unit of the color scanner / color printer, which controls a communication interface between the CPU 201, the color scanner 121, and the color printer 122. Further, the interface unit 120 stores one line of image data output from the scanner 121 by line-by-line image reading, transfers the image data to the image memory 132 in accordance with the bus cycle of the CPU bus 223, or stores the image data in the page memory 133. Done Y,
The necessary image signals in M, C, and K are read out by a CPU bus cycle, raster scans of the color printer 122 are stored, and the image signals are transmitted to the printer 122 in accordance with the raster scan of the printer 122. It performs signal speed conversion and synchronization for each line.

Reference numeral 155 denotes a bit map memory corresponding to the maximum recording paper size in the printer 122. The bit map memory 155 stores whether a hard copy formed by the image signal of the page memory 133 is recorded as a character or a halftone image. This is a memory specified for each pixel.

Reference numeral 113 denotes a VRAM composed of three colors of red (R), green (G), and blue (B) to be displayed on the color CRT 110.

The graphic memory 131 stores a graphic file in the same manner as the graphic memory in FIG. 16, and further stores a code indicating the display color of the graphic file.

The image information data developed in the graphic memory 131 includes color data of continuously changing density such as a gradation pattern in addition to a font pattern as character information. This data is developed as 8-bit gradation data for each of R, G, and B, similarly to the image information read from the scanner 121. At this time, identification data is prepared which indicates whether to output to the printer as character data or half-tone data accompanying the 8-bit gradation data.

The text memory 130 stores a text file in the same manner as the text memory 230 in FIG. 16, and a color code indicating a display color is added to each character code similarly to the graphics memory 131.

These graphic memory 131 and text memory 130
In this embodiment, the color code stored in the image data is formed by three bits, and is represented by red (R), green (G), blue (B), magenta (M), cyan (C), yellow (Y), and black (K). 7) are represented.

The code image conversion unit 152 and the graphic processing unit 151 correspond to the conversion unit 252 and the processing unit 251 in FIG. 16, respectively, and convert the bit image obtained by converting the code of the text file and the bit image of the graphic file into the above-described color code. Is developed as a color bit image in the VRAM 113 or the page memory 133 in response to the request.

The natural image processing unit 150 converts the R, G, B color data when developing the image data in the page memory 133 into Y, M, C, K in addition to the image data reducing function of the natural image processing unit 250 in FIG. It has a function of converting to color data, a function of determining whether the data is recorded as characters or a photograph from the R, G, B data in the image memory 132, and a function of writing the determination result to the memory 155. .

 FIG. 2 is a diagram showing a configuration example of the printer 121.

The printer 121 is a full-color laser beam printer, and the image signal sent from the interface 120 is processed by the processor 401 according to the characteristics of the printer.
WM modulation is performed, and the semiconductor laser 402 is driven according to the PWM signal. The laser light generated by the semiconductor laser 402 is main-scanned by a polygon mirror 403 rotated at a predetermined speed by a motor (not shown), is imaged on a photosensitive drum 406 via an optical system 404 and a mirror 405, and is uniformly charged in advance. A latent image is formed on the photosensitive drum 406. Reference numeral 407 denotes a rotary developing device that converts the latent image formed on the photosensitive drum 406 into Y, M,
Develop with C, K toners. The developed toner images of each color are sequentially transferred to a sheet on a transfer drum 408. The paper supplied from the paper cassette 406 is wound around the transfer drum 408 in advance, and toner images of each color are formed on the same paper in a superimposed manner. The image signal sent from the interface 220 in a frame-sequential manner, ie, Y (yellow), M
In response to the signals of the respective color components of (magenta), C (cyan), and BK (black), the rotary developing device 407 respectively controls Y, M, C, and BK.
Develop with toner. After all the toner images of Y, M, C, and BK have been transferred to the sheet, the sheet is released from the transfer drum 408, is conveyed by the conveyor belt 409, passes through the fixing device 410, is fixed, and is discharged outside the apparatus. Is done.

FIG. 3 shows a configuration example of a laser imaging system in the printer shown in FIG.

The reference signal BD for each raster scan of the laser scan is a BD mirror
Optical fiber 505
And is generated by detection by a BD detection circuit 501 composed of a photoelectric conversion element via the. By sending this BD signal to the scanner / printer interface 120, the interface 120 outputs a one-line horizontal synchronization signal HSYNC1 synchronized with the BD signal, a video clock 1, which is an image clock,
8-bit signal Video1, which is image data, indicating the number of recording lines
Screen Data1 is sent.

In this embodiment, the effective length of the photosensitive drum 408 in the laser scanning direction (main scanning direction) is the length of the short side of the A3 size, and the recording density is the main scanning direction / drum rotation direction (sub scanning). Both are 400 dots / inch (dpi) and 400 lines / inch (lpi), and the peripheral speed of the drum is 0.3 inch per second. Therefore, the period of the BD signal is 1/120 line seconds, that is, 8.3.
3 milliseconds.

The interface 120 transmits one line of image data at an arbitrary speed of 4677 pixels of A3 width in accordance with the BD signal having a period of 8.33 milliseconds. The image data Video1 and the line frequency data ScreenData1 from the interface 120 are stored in the image frequency conversion unit 502 comprising one line of FIFO memory, and the image clock Vid from the laser pulse width modulation unit 503 is stored.
Read as Video2 and Screen Data2 by eo Clock2.

The frequency of this Video Clock2 is defined by 70% of the effective use rate of the dodecahedral mirror. That is, to read 4677 pixels of A3 width image data at 70% of the 8.33 ms BD period
The frequency of Video Clock2 is 802KHz.

Video Clock2 synchronized with BD signal and main scanning synchronization signal H
FIG. 4 shows the generation timing of SYNC2.

As can be seen from this figure, the laser pulse width modulation section 503 has an oscillator having a frequency fc 64 times that of Video Clock 2,
Video Clock2 is generated in synchronization with the rise of the signal. Then, in the pulse width modulation section 503, Video Data2
Is subjected to pulse width modulation by comparison with a triangular wave signal having a period corresponding to the number of recording lines specified by Screen Data 2 and is given to the laser unit. Pulse width modulation (PW
M) The laser light whose blinking is controlled in accordance with the image signal forms a latent image having a potential corresponding to the pulse width on the photosensitive drum 408. In the present embodiment, the number of recording lines indicates the number of triangular waves for an image signal per inch.

FIG. 5 is a detailed diagram of the pulse width modulation section 503 that performs the above-described pulse width modulation operation.

The clock generator 610 generates Video Clock2, HSYNC2, and Screen Clock shown in FIG. 4 in synchronization with the BD signal. 40
An 8-bit image signal Video2 having a resolution of 0 dpi is a latch 611.
After the timing is adjusted by D / A converter 613
It is converted into an analog image signal 604 of 400 dpi. Screen C
lock is divided into 1/2 and 1/4 by dividers 603 and 604 respectively, and R and C
Are applied by the triangular wave generators 601 and 602 comprising an integrator of
Thereby, a 400-line triangular wave and a 200-line triangular wave shown in FIG. 4 are formed, respectively.

The two triangular waves having different periods are output from comparators 605, 60
At 6, the pulse width is compared with the analog image signal 604 from the D / A converter 613 and pulse width modulated. The two pulse width modulation signals 614 and 615 are selected by the selector 608, and the laser light is output as a drive signal for flashing control.

Here, an example of PWM modulation using the 200-line triangular wave 617 by the triangular wave generator 2 and an example of PWM modulation using the 400-line triangular wave 616 by the triangular wave generator 3 for the same image signal 614 are described in the sixth section.
Figures (a) and (b) show these respectively.

This switching of the triangular wave is effective, for example, in the case where image formation by electrophotography is performed by controlling the blinking of a laser beam with a pulse width modulation signal. That is, the reproducibility of each image such as a character or a photograph is improved by selectively using the electrophotographic material according to the characteristics of the electrophotographic material such that the longer the triangular wave generation cycle is, the better the gradation is, and the shorter the triangular wave is, the better the resolution is. .

That is, character recording requiring resolution is performed by using a PWM signal obtained by comparing 400 dpi image data with a 400-line triangular wave 616, and gradation is required by using a 200-line triangular wave 617 PWM signal. Perform halftone recording. Switching between these two PWM signals is interface 1
Controlled by Screen Data1, which is read data from the screen configuration memory sent from 20, character recording is performed when Screen Data1 is at "H" level, and halftone recording is performed when Screen Data1 is at "L" level.

FIG. 7 shows a configuration example of the color scanner 121. A color separation image sensor 903 such as a three-line CCD is used to separate the image information of the original 902 placed on the original glass 901 pressed by the original cover 900 and read. The reflected light from the original 902 illuminated by the light source 904 is imaged on the image sensor 903 by the lens 908 via mirrors 905, 906, and 907. First optical unit 910 including light source 904 and mirror 905 and mirror
The second optical unit 911 composed of 906 and 907 moves at a relative speed of 2: 1. This optical unit 910,91
1 is moved left and right (sub-scanning direction) at a constant speed by a stepping motor 909.

The three line CCDs used in this example were a red filtered CCD 1020 and a green filtered CCD 1021.
And a CCD 1022 to which a blue filter is applied is formed in parallel on the same chip 302. Each CCD has 5,000 pixels, and reads 297 mm in the longitudinal direction of an A4 document at a resolution of 400 dots / inch.

The R, G, and B three-line CCDs are each shifted by 18 lines in the sub-scanning direction at a resolution of 400 lines / inch. In general, a color scanner outputs a color separation signal of the same line on the platen as, for example, R, G, B signals standardized by the NTSC method or the like. Must be corrected. For this reason,
In the present embodiment, as shown in FIG.
A large buffer 210 for delaying the line and a small buffer 211 for delaying the image signal of the G line by 18 lines are provided.

In FIG. 8, signals read by the three lines of CCDs 1020, 1021, and 1022 are amplified by amplifiers 1004, 1005, and 1006, respectively.
The signals are converted into 256-stage digital signals by the D converters 1007, 1008, and 1009. A clock generator 1013 includes two-phase clocks 1016 and 1017 for driving CCDs 102 to 1022 and a pixel clock 101.
9 and HSYNC1018 which is a line synchronization signal.

256 delayed by 36 lines by large buffer 1001
The R signal of the stage, the G signal of the 256 stage delayed by 18 lines by the small buffer 1011, and the B signal of the 256 stage read from the CCD 1022 are respectively supplied to the masking circuit 1012.
R-NT which is input to the r, g, b inputs and is a 256-stage NTSC R, G, B signal by the masking matrix operation of the following equation
It is converted to SC1028, G-NTSC1029, B-NTSC1030. That is, Becomes

These three color separation reading signals are synchronized signals H for each line.
Along with -SYNC, it is input to the scanner / printer interface 120 by the pixel clock V-CLK, and is written to each of the R, G, and B areas of the image memory 132 by DMA transfer.

FIG. 9 shows an operation of expanding the text data stored in the text memory 130 into the page memory 133. The text memory 130 stores text codes to be expanded in ASCII codes. The first two bytes are
The number of stored text, which is a hexadecimal code. The text memory 130 now has six characters: red “R”, green “G”, blue “B”, yellow “Y”, magenta “M”, and cyan “C”. Is stored. The ASCII code 52H, 47H, 42H, 59H, 4DH, 43H indicating R, G, B, Y, M, C has a color code indicating the color of each character, that is, 00H indicating the red color, green color 01H indicating blue, 02H indicating blue, 05H indicating yellow,
04H indicating magenta and 03H indicating cyan are added. In addition, the black color is represented by a color code of 06H.

The screen configuration information table 254 stores the expansion format of the code in the text memory described in the CPU 201 in the page memory 133. An identifier 00H indicating a text code is stored in the first 0 byte. The first byte and the second byte store the development start row address of the page memory 133 and the screen configuration memory 155. The development start column address is stored in the third and fourth bytes. The number of characters arranged in one line is stored in the fifth and sixth bytes, and the number of characters arranged in one column is stored in the seventh and eighth bytes.

The code image conversion unit 152 is constituted by a dedicated CPU, and has a memory based on the procedure shown in the flowchart of FIG.
133, code information is expanded in the memory 155.

Here, as an example, the operation when the recording color in the printer is magenta is described.

First, when developing a text image,
In step 1201, a text code table whose head data is 00H is searched from the screen configuration information table 254, and the following 8-byte data is read. In step 1202, the starting address 2 of the text memory 130, the page memory 133, and the development start row address 248H and the development initiator address 248H of the screen configuration memory 155 are obtained, and each memory pointer is set.

In step 1203, three codes of three characters R, G, and B constituting the first line of the first line and each recording color code are read from the text memory 130. Next, at step 1204, a bit image corresponding to each code is read out from the font ROM 212, and is expanded in the multi-valued bit image memory for one line in the code-to-image conversion unit 152. In color recording by a printer, a color is expressed by mixing (toner) of the four color developing materials of yellow, magenta, cyan, and black. The mixing ratio of the developing material for realizing the color corresponding to each color code is as follows. It looks like Figure 11.

To achieve this, the recording density data of the "R" character recorded in red color on the magenta developing material is developed in the multi-valued bit image memory as a value E5H of 90% of the 8-bit full range value FFH. Also, "G" recorded in green color
Since the characters do not use the magenta developing material, they are not developed in the multi-valued bit image memory. Similarly, the "B" character recorded in blue is developed as FFH in the multi-valued bit image memory.

Next, in step 1205, the code-to-image conversion unit 15
The number of row addresses for DMA-transferring the data expanded in the multi-valued bit image memory in 2 to the page memory 133 and the screen configuration memory 155 is calculated. In this case, one character is vertical,
Since it is also 64 dots, the number of line addresses is 3 characters and 19
Two addresses. By performing DMA transfer in step 1206 using this value, multi-valued bit images for one row are sequentially developed from the pointer addresses (248H, 288H) of the page memory 133 and the screen configuration memory 155. At this time, since the screen configuration memory 155 is a binary bit map memory, data 1 indicating that recording is performed with 400 lines is developed only when the multi-valued bit image for one row is not 0.

Next, in step 1207, the screen configuration information table 254
The number of column characters represented by the 7th and 8th byte data is reduced by 1, and whether or not the expansion of all the text data has been completed is determined based on whether the value is 0 or not. As a result, in the present embodiment, another line of data is stored in the text memory 130.
Therefore, the process returns to step 1202 to set a pointer for data expansion on the second line. The pointer of the text memory 130 is at address 8 indicating the fourth character "Y", and the pointers of the page memory 133 and the screen configuration memory 155 are increased by 64 addresses in the line direction for line change, and (248H, 288H)
Becomes Hereinafter, the data development of the second row is performed in the same manner as the first row by the processing of steps 1203 to 1207. As a result, all the text data pages memory 133 and the screen configuration memory 155 are developed.

As described above, magenta data is developed in the printer 122, and data is developed in the same manner for other yellow, cyan, and black.

In order to expand the multi-valued scanner read data stored in the image memory 132 into the page memory 133, the natural image processing unit 150 performs light amount / density conversion of read color data which is a complementary color of a developed color in the printer 122. . In the natural image processing unit 150, the expanded data
It is determined whether to perform the character recording of the 0 line or the photograph recording of the 200 line, and the result is developed in the screen configuration memory 155 for each pixel data.

FIG. 12 shows the operation of the natural image processing unit 150 when developing magenta developed color data. When the content of the head address of the screen configuration information table 254 is 02H, it indicates that the natural image data read by the color scanner 121 stored in the image memory 132 is expanded in the page memory 133. In the subsequent four bytes, the start address of the exposed rectangular area in the image memory 132 is stored. In the next four bytes, the end address of the exposed rectangular area in the image memory 132 is stored. The next four bytes store the destination address of the natural image data of the extracted rectangular area in the page memory 133 and the screen configuration memory 155. The data of the leading address of the exposed rectangular area in the image memory 132 is stored. Is expanded corresponding to this expansion destination address.

In the screen information table of FIG. 12, the row address 490H, the column address 490H and the row address DBOH,
Data for developing the natural image data of the rectangular area up to the column address DBOH into the rectangular area from the row address 836H, the column address 836H to the row address 1156H, and the column address 1156H of the page memory 133 and the screen configuration memory 155 is stored. I have. The data in the table 254 is set in the natural image processing unit 150 by the CPU 201, and the natural image data is transferred by DMA transfer. FIG. 12 shows the formation of image data on the page memory 133 recorded by the magenta developing material of the printer 122. Natural image data of a green image memory having a complementary color relationship with magenta is transferred. 156 is G
An address line for transferring local data from the data image memory 132 to the natural image processing unit, and 157 is a local data line.

In this embodiment, when natural image data is recorded by a printer, image information of a portion having a large density change (for example, a character portion) such as an edge portion of a character is recorded by using a 400-line triangular wave, and a continuous image such as a photograph is obtained. The image information of the portion where the density is changed (halftone portion) is recorded by using a 200-line triangular wave. Therefore, only the edge portion of the character A in the image memory 132 is developed as 1 in the image configuration memory 155 for character recording, and is developed as 0 for halftone recording in the other portions. The determination of the magnitude of the density change for performing the character recording is performed based on the Laplacian operation value of the four pixels around the image data of interest in the natural image processing unit 150.

The Laplacian operation value L is obtained by the following convolution operation.

FIG. 13 shows the configuration of the natural image processing unit 150.

1501 is the local row address 1 to the image memory 132
This is a row address counter for generating 504, and counts by a bus clock sent from the CPU bus 223 in correspondence with DMA transfer for each pixel from the natural image processing unit to the page memory 133 and the screen configuration memory 155. 1502 is a column address counter that generates a local column address 1505,
The count operation is performed by the output 1512 of the comparator 1503 indicating the end of reading of the image data of one row in the direction of the arrow in the figure from the image memory 132. The output 1512 of the comparator 1503 returns the row address counter 1501 to the initial value.

Reference numeral 1506 denotes a line buffer memory that stores three lines of natural image data delayed one line at a time.
Addressed by 1504. Image data is simultaneously read from the memories a, b, and c from the address specified by the row address 1504 and sent to the pixel delay unit 1507, and then the image data read from the image memory 132 is stored at the same address in the memory a. Is written, the read data from the memory a is written to the memory b, and the read data from the memory b is written to the memory c. This results in three rows of memory
From 1506, three pixel data having the same row address and continuous column address is read.

This data is delayed one pixel at a time by the bus clock in the pixel delay unit 1507, and then the convolution operation unit 15
At 08, the Laplacian operation of the second expression is performed. The calculated values L having positive and negative values are all converted into positive data in the absolute value calculation unit 1509. This converted data is output from comparator 1510.
The value is compared with the fixed value 80H set by the CPU 201.
If the comparator input data is larger than 80H, data "1" indicating a character recording pixel having a large density change is output,
If it is smaller than 80H, data “0” indicating a halftone recording pixel with a small density change is output, and the screen configuration memory
It is expanded by DMA transfer to 155 corresponding addresses.

The green reading data of the target pixel quadrupled by the convolution operation unit 1508 is converted into a complementary magenta image by the light amount / density conversion unit 1511 and stored in the page memory 133.
MA is transferred. Generally, the light quantity / density conversion converts the light quantity signal E into a density signal by the following equation.

V = -logE (Equation 3) In Equation 3, the light amount E is a value normalized as the maximum value 1, and when E approaches 0, V increases to infinity. Therefore, the value of E is made variable from 0 to 255, and when E = 1, V = 2
The conversion table of the fourth formula, which is set to 55, is used for the light quantity / density conversion unit.

The CPU 201 sets the start address 490H in the row address counter 1501 and the start address 490H in the column address counter 1502 before transferring the natural image data.
The last row address of the rectangular area is set in the comparator 1503. Furthermore, the transfer start address (836H, 836H) of the page memory 133 and the screen configuration memory 155 to the DMA controller 214.
Then, the number of one row data 920H and the total number of columns 920H are set, and DMA transfer is started. In this way, a printer for natural image data
Development for 122 magenta colors is performed. The processing for other cyan, yellow, and black is executed in the same manner.

In this manner, the magenta multi-valued image data developed in the page memory 133 and the one-bit character / halftone recording switching signal developed in the screen configuration memory 155 are synchronized with the image forming operation of the printer. The data is transferred to the color printer 122 through the printer interface 120.

Note that a pattern requiring halftone recording such as a gradation pattern stored in the graphic memory 131 is stored in the corresponding area of the screen configuration memory 155 in accordance with the development position of the image data in the page memory 133. By developing bit data 0 to be recorded, halftone recording is performed when a hard copy is created by the printer 122.

(Second Embodiment) When character information or the like is not included in the natural image data, it is not necessary to switch the recording mode in pixel units. In this case CPU2
01 is the main scanning pixel address H on the recording paper as shown in FIG.
By designating the sub-scanning pixel addresses V1, V2, V3, V4 of 1, H2, H3, H4, the recording mode can be switched between inside and outside the rectangular area defined by those addresses. For example, in the example of FIG. 9, the text codes R, G, B, Y, M, and C are expanded. V1 = 248
By setting H, V2 = 2C8H and designating H1, H2, V1, V2, the area including the periphery of the character code is recorded as a character using a 400-line triangular wave.

The main scanning and sub-scanning address values of this rectangular area are calculated by the CPU 201 as follows from the text code development position information stored in the screen configuration information table 254 shown in FIG.

H1 = (line start address) H2 = (line start address) + 64 x (number of line characters) V1 = (column start address) V2 = (column start address) + 64 x (number of column characters) where 64 corresponds to the text code The dot size in the row direction and column direction of a font for one character.

When the recording mode of the printer 122 is switched based on the code information in this manner, a switching designation unit for each pixel such as the screen configuration memory 155 in FIG. 1 is not required. Instead, the scanner / printer interface 120 has a rectangular area forming unit synchronized with the transfer of image data, and generates a character / halftone recording switching signal (Screen Data 1).

 FIG. 15 shows a configuration example of the rectangular area forming unit.

Reference numeral 1701 denotes a main scanning address counter, which is counted by a video data transfer clock Video Clock 1 and is cleared by a main scanning synchronization signal HSYNC1. Reference numeral 1702 denotes a sub-scanning address counter which counts the number of lines by HSYNC1 and is cleared by a clear signal from the CPU 201 before transferring one page of image data.

1705 to 1711 are comparators, and address 1703,1
704 and rectangular area data H1 set by CPU 201
H4 and V1 to V4. Reference numerals 1712 to 1715 denote SR flip-flops, each of which forms a section signal by a signal from a corresponding comparator. The F / F 1712 forms a main scanning section signal from H1 to H2, and the F / F 1713 forms a main scanning section signal from H3 to H4. The F / F 1714 and the F / F 1715 form sub-scanning interval signals from V1 to V2 and V3 to V4, respectively. These signals cause the AND gate 1716 to go from (H1, V1) to (H
2, and V2), and the AND gate 1717 forms rectangular area signals from (H3, V3) to (H4, V4). These two area signals are combined by the OR gate 1718 and become a signal for switching between character and halftone recording of the printer.

As described above, the switching signal of the multi-value recording mode in the printer is generated at an arbitrary position in the page memory in accordance with the position of the expanded text data or natural image data or the degree of the density change of the data. By providing the means, it is possible to record the edge portion of information such as text data or character image data in a natural image that requires sharpness, and to record the halftone image such as a natural image or a gradation pattern. Enables density recording suitable for various types of information, such as recording of multiple gradations.

(Effect)

As described above, according to the present invention, according to the present invention, the recording density of each part of the image when forming the developed multi-valued image data is shown in correspondence with the developed multi-valued image data. Screen data is stored, the multi-valued image data and the screen data are supplied to a pulse width modulation section in synchronization with an image forming operation, and a pulse width modulation process is selected according to the screen data. Both sex images and character images can be reproduced with high quality.

In addition, since the discrimination process (screen data generation process) for selecting the pulse width modulation process is not required at the time of image formation, a delay circuit or the like for image data corresponding to the discrimination processing time is not required. Synchronization of multi-valued image data and the screen data is also easy,
As a result, there is an effect that the configuration of the pulse width modulation processing is simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a gradation image signal editing and recording apparatus to which the present invention is applied, FIG. 2 is a diagram illustrating a configuration example of a printer, FIG. 3 is a diagram illustrating an image forming unit of the printer in FIG. The figure shows a multi-value image recording control unit of the printer, FIG. 5 shows the operation of the PWM control of the printer, FIG. 6 shows the timing of generating an image synchronization signal for each line, and FIG. 7 shows the scanner 8 is a diagram showing an image signal forming unit of the scanner shown in FIG. 7, FIG. 9 is a diagram showing an operation of expanding multi-valued text data, and FIG. 10 is a control procedure for expanding text code data. FIG. 11 is a diagram showing the mixing ratio of the developer when recording the text code color. FIG. 12 is a diagram showing the operation of the natural image processing unit. FIG. 13 is a diagram showing the operation of the natural image processing unit. FIG. 14 is a diagram showing the configuration. FIG. 15 is a diagram showing a rectangular region generating circuit, FIG. 16 is a configuration diagram of a binary document image processing device, and FIG. 17 is a diagram showing an operation of the binary document image processing device shown in FIG. 110 is a CRT, 113 is a VRAM, 130 is a text memory, 131 is a graphics memory, 132 is an image memory, 133 is a page memory, 121 is a color scanner, 122 is a color printer,
201 is a CPU, 601 is a triangular wave generator 1, 602 is a triangular wave generator 2, and 608 is a selector.

Claims (1)

(57) [Claims] An image processing apparatus for developing input multi-valued image data and forming an image based on the developed multi-valued image data, wherein the image on which the multi-valued image data is developed is provided. Storage means; storage density storage for storing screen data indicating a storage density of each part of an image when forming the expanded multi-value image data in association with the multi-value image data expanded in the image storage means; Means, a first pulse width modulation signal generated by comparing the multi-valued image data expanded in the image storage means with a first pattern signal having a predetermined cycle, and a cycle of the first pattern signal. A pulse width modulation means for selectively outputting a second pulse width modulation signal generated by comparing with a different second pattern signal according to screen data stored in the recording density storage means. , An image processing apparatus for supplying multi-valued image data developed in the image storage means and screen data stored in the recording density storage means to the pulse width modulation means in synchronization with an image forming operation. .