JPH0481170A - Graphic processing unit - Google Patents

Abstract

PURPOSE:To express ruggedness (alias) smoothly and to improve the quality of an output picture by executing anti-aliasing processing to a border of an area designated by a coordinate designation means and outputting the picture data from a printer when picture processing is executed to the above area with respect to the picture data read by a picture reader CONSTITUTION:A CPU 202 stores a post-script (PDL) language received by a receiver 201 through an internal system bus 203 according to the program stored in a ROM 205. Then the PDL language by one page is received and stored in the RAM 204, then the anti-aliasing processing is applied to a graphic element in the RAM 204 and a multi-value RGB image data is stored in a plane memory section of a page memory 206 (the page memory 206 consists of R, G, B plane memory sections and a characteristic information memory section). Then the data in the page memory 206 is fed to a picture processing unit 400 via a transmitter 207.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphic processing device equipped with coordinate input means for performing image editing processing, and more specifically, the present invention relates to a graphic processing device equipped with a coordinate input means for performing image editing processing, and more specifically, to The present invention relates to a graphic processing device that smoothly expresses (alias).

[Conventional technology]

Conventional digital copying machines have an editing function that allows editing processes such as erasing outside or inside areas of input image information using a digitizer, numeric keypad, etc. Many things have been proposed.

Taking as an example the deletion within a specified area by a digital copying machine equipped with the editing function as described above, the editing operation will be explained using FIGS. 34 to 36.

FIG. 34 shows an image (alpha head "A") read by the image reading device, and FIG. 35 shows area data input using a digitizer or numeric keypad. When intra-region deletion processing is performed on the above image data using the input region data, an image as shown in FIG. 36 is obtained.

As a result, the image data shown in FIG. 34 is subjected to image processing according to the designated area data.

[Problem to be solved by the invention]

However, since the above area data input using a digitizer or numeric keypad is treated as binary data, jaggedness (aliasing) occurs at the boundary of the area specified by the area data, degrading the quality of the output image. There was a problem with this.

The present invention has been made in view of the above, and it is an object of the present invention to smoothly express jagged edges (aliases) that occur at the boundaries of areas designated by area data, and to improve the quality of output images.

[Failure to solve the problem]

In order to achieve the above object, the present invention includes a reading means for reading multivalued image data from a document, a coordinate input means for specifying an area in which image editing processing is to be performed in the image data read by the reading means, and anti-aliasing processing means for performing anti-aliasing processing on the boundary of a region specified by the input means; image processing means for calculating the image data and region data; The present invention provides a graphic processing device including a graphic output means for converting and outputting a graphic.

[For production]

In the graphic processing device of the present invention, when performing image processing processing on the area specified by the coordinate specifying means on image data read by the image reading device, anti-aliasing processing is performed on the boundary portion of the area. After that, the image data is output from the printer.

〔Example〕

The graphic processing apparatus of the present invention will be described below based on the drawings. Multi-value drive (2) The operation of the graphic processing apparatus according to this embodiment will be explained in detail in the following order.

The graphic processing device of this embodiment uses a page description language (P
ageDescriptionLanguage
This configuration is capable of image formation of both image information, including vector data written in the PDL language (hereinafter referred to as PDL language) and image images read by an image reading device.

The configuration of the graphic processing apparatus of this embodiment will be explained below with reference to FIG.

■Schematic configuration of graphic processing device The graphic processing device includes a host computer 100 that creates documents written in the PDL language (Postscript language is used in this embodiment), and a PDL that is sent page by page from the host computer 100. Red (R), green (G), blue (B) while applying anti-aliasing processing to the language.
) PDL controller (anti-aliasing processing means of the present invention) 200 that develops into a three-color image;
An image reading device 300 that reads image information via an optical system unit, and an image processing device 4 that inputs an image output from the PDL controller 200 or the image reading device 300 and performs image processing (details will be described later).
00 and a multi-value color laser printer 500 that prints the multi-value image data output by the image processing device 400.
, a PDL controller 200, and an image reading device 300
, an image processing device 400, and a multivalued color laser
It is composed of a system control unit 600 that controls the printer 500, and a digitizer 700 that inputs coordinates and specifies an area to be edited on an image.

■Anti-aliasing processing In the field of computer graphics, a technique called anti-aliasing processing is used to make the displayed image more beautiful when displaying it on a CRT, which is the output medium. This process applies brightness modulation to the jagged parts (called aliases) on the stairs as shown in Figure 2(a), and visually smooths the displayed image as shown in Figure 2(g)). It is something.

The following methods are known as anti-aliasing processing methods.

i, Uniform averaging method 1!0 weighting is an averaging method iii, Convolution integral method Each of the above methods will be explained in order.

, Uniform averaging method In the uniform averaging method, each pixel (pixel) is N*M (N, M
is a natural number), performs rask calculation at high resolution, and then calculates the brightness of each pixel by taking the average of N*M subpixels. Anti-aliasing processing using the uniform averaging method will be specifically explained with reference to FIG. 3(a). If the edge of the image overlaps a certain pixel (here, it is assumed that the image is connected to the bottom right of the diagonal line), and when anti-aliasing processing is not performed, as shown in Figure (a), The brightness kid of this pixel is assigned the highest brightness of the displayable gradations (for example, kid·255 for 256 gradations). When performing anti-aliasing processing on this pixel using the uniform averaging method with N=M=7, the pixel is decomposed into 7*7 sub-vixels, as shown in Figure (b).
Count the number of sub-vixels covered by the image. The count number (28) is divided by the total number of sub-vixels in one pixel (49 in this case), normalized (averaged), and multiplied by the maximum brightness (255) to calculate the brightness of that pixel. In this way, in the uniform averaging method, the brightness of each pixel is determined by taking into consideration how the image covers each pixel.

ii. Weighting is an averaging method The weighting and averaging method is a partial modification of the uniform averaging method. In contrast to the weighting method, which simply counts the number of sub-vixels in the image, the averaging method assigns a weight to each sub-vixel, so that the influence on the brightness kid of that sub-vixel differs depending on which sub-vixel the image falls on. I have to. Note that the weight at this time is given using a filter.

Referring to Figures 4(a) and (b), an example is shown in which the same image data as in Figure 3(a) is weighted using the same dividing method (N=M=7) and the averaging method. .

FIG. 4(a) shows the filter (here, conefi
lter), and the corresponding sub-vixel is given the same weight as this characteristic. For example, the weight of the sub-vixel in the upper right corner is 2. When an image is applied to each sub-vixel, the weight value given by the filter characteristics becomes the count value of that sub-vixel. Same figure (G))
In the figure, the display pattern of the image is changed depending on the weight of the sub-vixels. In this case, if we count the weighted sub-vixels of the image, we get
It becomes 199. This value is divided by the sum of the filter values (336 in this case) corresponding to uniform averaging, averaged, and multiplied by the maximum brightness to calculate the brightness of this pixel. In addition, as a filter, Fig. 5 (a), □□□
), (C), and (d) are known.

Mountain-0 convolution method The convolution method is a method that also refers to the appearance of surrounding pixels when determining the brightness of one pixel. That is, around the l pixel whose brightness is to be determined, N
Consider the 'XN' pixels to correspond to the equal-averaging or weighted averaging pixels. 6th
The figure shows a convolution method with 3×3 pixel references. In this figure, the pixel whose brightness is to be determined is indicated at 61. The image continues to the bottom right of the diagonal line, and the sub-vixels painted in black are the sub-vixels that are counted.

Each pixel is divided into 4*4. Therefore, in this case, a 12*12 filter will be used. This method has the effect of removing high frequency components contained in a vector image.

On the other hand, a publishing system using a personal computer,
With the spread of so-called DTP (desk top publishing), systems for printing vector images, such as those used in computer graphics, have become widely used. A typical example is a system using Adobe's Post Script. PostScript is a page description language (Page Des
criptionLanguage: Hereafter, PDL
It belongs to a language genre called "Japanese language", and describes the form of the contents of a document, including the text (letter part), graphics, and their arrangement and appearance. Hector font is used as the character font in such systems. Therefore, even if characters are scaled, the print quality can be dramatically improved compared to systems using bitmap fonts (for example, conventional word processors).
Another advantage is that character fonts, graphics, and images can be mixed and printed.

However, the resolution of the laser printers used in these systems is at most 240dpi to 400dp.
There are many i, computer and graphics C
Similar to RT display, there is a problem in that aliasing occurs due to the low resolution. For this reason, even when printing using a laser printer, there is a need to perform anti-aliasing processing to improve the quality of the printed image.

However, according to the anti-aliasing processing method and device described above, one pixel is divided into a plurality of sub-vixels (for example, 49 sub-vixels), the number of sub-vixels to be filled is counted, and the area ratio ( There is a problem in that it takes time to calculate the area ratio (brightness), which hinders improvement in display speed or printing speed. In particular, the convolution method has problems in that it requires a large amount of calculation and affects multiple pixels, making it difficult to improve processing speed.

In view of the above, an anti-aliasing method has also been proposed that calculates the area ratio at high speed without performing sub-vixel division or counting the number of filled pixels.

1v, method for obtaining approximate area ratio of edge pixels This anti-aliasing processing method calculates the presence or absence of an intersection between vector data and a predetermined group of straight lines when edge pixels are divided by a predetermined group of straight lines, and the type of edge. Based on this, an approximate area ratio of the edge pixel is obtained. Below, Figure 7 (
A method for obtaining an approximate area ratio from the presence or absence of an intersection and the type of edge will be described in detail with reference to a) to ge).

A straight line L1 given by vector data (hereinafter referred to as vector straight line L1) and each line y in the sub-scanning direction y
o, Vr-3'z intersect at the intersection X O+ X l+ X Z as shown in FIG.
+ 'J oL (X l+ y +) to the following formula (1)
It can be found by

X I -χ〇 On the other hand, focusing on pixel P, a new x'y' coordinate system is set, and as shown in FIG. 7(b), the pixel P is drawn as a straight line!
1. l□, ls, 1.4.1s, Eb, 12-
It is divided by eight straight lines (hereinafter referred to as dividing straight lines) of 12 m. Here, the equation of each straight line is the following equation (
3) to θ0).

Also, assuming that the equation of the vector straight line L1 obtained using equation (1) above is y = - (1/3) x + (7/6) - (2), this vector straight line L1 and pixel P are Dividing straight line e,,i,,i,,e,,e5゜z,,z,
, p, and the coordinates of the intersections are shown in the following table.

Here, the range of is the dividing line 13. There are three dividing straight lines, la and 18. Conversely, within the range of this pixel P, the three dividing straight lines x3. i,,i,
The equation of a vector straight line with only and intersection points is shown in Figure 7 (
If the intersection points are A and B as shown in C), the coordinates of intersection A are (1/3<x'≦2/3.y'
-1), the coordinates of the intersection B are (x'-L 2/3<y'<1
) will definitely pass through the range. Therefore, the three dividing straight lines f3. j2. ．． The area ratios of pixels P that are divided by vector straight lines that intersect only with f are close to each other. In other words, when a group of vector straight lines that have intersections with a predetermined dividing straight line group are set as one set, The area ratio of the pixels P divided by the set of vector straight lines indicates a similar area ratio within a predetermined range. Therefore, the vector straight line and the dividing straight line 1+, lz, E3, 14. is, lb, 1
7. The individual area ratios of the set classified based on the intersection information with j2a can be approximated to one area ratio.

Therefore, in this anti-aliasing processing method, a set of vector straight lines is created based on the intersection information and edge information indicating which edge is on the left or right, and an approximate area ratio is calculated for each set in advance. For example, a LUT (Look Up Table) as shown in FIG. 7(d) is created which includes intersection information, edge information, and approximate area ratio. Then, when performing anti-aliasing processing,
Instead of performing sub-pixel division and calculating the area ratio of edge pixels, based on intersection information and edge information,
The output adjustment for edge pixels is performed by inputting the corresponding approximate area ratio from the LUT.

In the LOT shown in FIG. 7(d), the edge information flag indicates a left edge when the left edge flag = 1 and the right edge flag is -0, and indicates a right edge when the left edge flag = 0 and the right edge flag = 1. .

Also, when the left edge flag = right edge flag = 1,
It represents a vertex as shown in (e) in the same figure, and the division straight line flag =
1, each dividing line 1. , l! 2...
・It shows that 18 and the vector straight line intersect (that is, there is an intersection). The figure (e) shows a straight line that can be considered under the conditions of the LUT data D1, and the data D also includes the approximate area ratio of the diagonally shaded portion shown in the figure (e) as information. Similarly, the straight line that can be considered under the conditions of the data D2 of the LUT is shown in (Figure 1), and the data D2 includes the approximate area ratio of the shaded portion shown in Figure (Figure 2) as information. Therefore, for example, when calculating the area ratio of the vector straight line shown in FIG.・・・・・・Find the intersection with 28, then use the edge information determined by the PDL specifications to determine whether the edge is a left edge or a right edge, and based on these intersection information and edge information, create a LUT. Obtain the applicable approximate area ratio from .

■Configuration and operation of PDL controller FIG. 8 shows the configuration of the PDL controller 200, which includes a receiving device 201 that receives the PDL language sent from the host computer 100, and storage control and control of the PDL language received by the receiving device 201. A CPU 202 that executes anti-aliasing processing, an internal system bus 203, a RAM 204 that stores PDL language to be transferred from the receiving device 201 via the internal system bus 203, and a ROM 205 that stores anti-aliasing programs and the like.
, a page memory 206 that stores multivalued RGB image data subjected to anti-aliasing processing, a transmitting device 207 that transfers the RGB image data stored in the page memory 206 to the image processing device 400 , and a system control unit 600 . It is composed of an I10 device 208 that performs transmission and reception.

Here, the CPU 202 receives the P received by the receiving device 201.
The DL language is stored in the RAM 204 through the internal system hash 203 according to the program stored in the ROM 205. After that, receive one page of PDL language,
Once stored in the RAM 204, the graphic elements in the RAM 204 are subjected to an anti-aliasing processing method based on the flowchart described later, and the multi-level RGB image data is stored in the plain memory section of the page memory 206 (the page memory 206 has R, (consisting of plane memory sections of G and B, and a feature information memory section).

The data in the page memory 206 is then transferred to the transmitter 2
07 to the image processing device 400.

The operation of the PDL controller 200 will be described below with reference to FIGS. 9(a) and 9(b).

FIG. 9(a) shows a flowchart of processing performed by the CPU 202. As described above, the PDL controller 200 performs anti-aliasing processing on the PDL language sent page by page from the host computer 100, and generates three-color images of red (R), green (G), and blue (B). Expand to.

In the PDL language, graphics and characters are all described using hector data, and as the name "page description language" indicates, image information is processed in units of pages. Furthermore, one page is made up of at least one path, with each path being made up of one or more elements (graphic elements and character elements).

First, when PDL language is input, it is determined whether the element is a curved vector, and if it is a curved vector, it is approximated to a straight line vector and registered as a straight line element (line) in the work area. This is performed for all graphic and character elements within one path, and linear elements are registered in the work area for each path (processing 1).

Then, the straight line elements of the work area registered in this path unit are sorted by the starting X coordinate of the straight line (processing 2)
.

Next, in process 3, while updating the X coordinate one by one,
Performs filling processing using scanning lines. For example, in Figure 9 (
When performing the path filling process shown in b), the elements of the side across which the scanning line yc to be processed and the real values of the X coordinates across the scanning line yc (x, Xz shown in FIG. 9(b)
x3 x4) and AET (Active Edge)
Table: registers the X coordinate of the edge portion appearing on the scanning line). Here, the order of the elements registered in the work area is the order in which they were registered in process 1, so they are not necessarily registered in order of decreasing X coordinate across the scanning line yc. For example, process 1
If the linear element passing through scans iyc and X3 in FIG. 9(b) is processed first, then will be registered. Therefore, after the AET is registered, the elements on each side within the AET are sorted in descending order of X coordinate. Then, the first two elements of the AET are paired and the space between them is filled in (filling process using scanning lines). In this filling process, anti-aliasing processing
This is achieved by adjusting the density and brightness of the pixels in the edge portion according to the approximate area ratio. After that, move the processed side to A
Remove from ET, update scan line (update X coordinate), A
Similar processing is repeated until all edges in ET are processed, in other words, until all elements in one path are processed.

The operations of process 1, process 2, and process 3 described above are executed pass by pass, and repeated until all passes for one page are completed.

Next, the anti-aliasing process executed during the scan line filling process of process 3 described above will be described in detail with reference to the flowchart of FIG. 9(C).

Here, for example, in process 1 of FIG. 9(a), FIG.
If a pentagon ABCDE as shown in a) is input, this figure has the following elements.

(() AB, BC, CD, DE, EA (7) Five line vectors (represented by real numbers) (0) Color and brightness values inside the figure This figure is shown in Figure 10 (b) by the above operation. As shown in FIG.

That is, (c) Starting point coordinate values (real number expression) of the vector elements ((a) above) forming the starting point and ending point of the straight line vector (d) Slope information (near ) Characteristic information of the start point and end point of a straight line vector (right edge, left edge, apex of a figure, line of 1 dot or less, intersection of straight lines, etc.) In the flowchart of FIG. 9(C), first, antialiasing processing is started. Pixel X, (X+ in the same figure (b)
5401), and calculate the equation of the straight line from the intersection with the scanning line yc to be filled (
S402). Equation of this straight line and dividing line 1,,! 2
．． 13. l<, j2s, lb, 17.41! e
(S403), and based on the edge information (left edge, right edge, or apex of the figure) in the feature information described above, refer to the LUT and read the corresponding approximate area ratio (S404) ). Thereafter, the image data including the approximate area ratio is transferred to Line Hanfa (5405),
Move by 1 pixel in the X coordinate direction (5406), move by 1 pixel in the X coordinate direction
The X coordinate value of the pixel moved in the coordinate direction is the antialiasing completed pixel X, x2. If the end pixel is not X8, the process returns to 5403 and the above process is repeated, and the end pixel
If it is 8, the process advances to 5408 (S407).

Subsequently, in 5408, it is determined whether all the pixel data of the scanning line yc has been processed, and if it is not finished, the next image data is set (data shift: 5410), and the processing is repeated from 5401. On the other hand, if all the pixel data of the scanning line yc has been processed, the line yc is filled with line buffer data (S409).

The CPU 202 repeats the above processing up to the last pixel of the scanning line (y coordinate), and at the same time updates the contents of (c) above with the information of (d) above. The approximate area ratio of the figure in FIG. 1O(a) obtained by the anti-aliasing process in this way has a value as shown in FIG.

Here, the figure in FIG. 10(a) has a background color of white (maximum brightness: 255) and a figure color of red (maximum brightness: 255).
55), the approximate area ratio k (first
(See Figure 1), the brightness values of each color of the figure (red), (green), and Kb (blue) are determined based on the following formula.

Kr = Ki+Xk + Kt□X(1-k)K
9 = KGI X k+ KG2X (1-k) Kb
= Ki+Xk + KmzX(1k) However,)
(*+, KGI, and Kll each indicate the brightness value of the color (red, green, and blue, respectively) of the figure given in (II+) above, and K, □, KGZ, and Kg□ are the brightness values of each previously painted color. Note that KR□, KGZ, and KBZ refer to data in each plane memory section corresponding to RGB of the page memory 206.

The brightness values K1.1K91 and K91 obtained in this way are stored in the RGB image in the corresponding brain memory section of the page memory 206, as shown in FIGS. 12(a), (b), and (C). Stored as data.

Here, for comparison, RGB image data without anti-aging processing is shown in Figure 13(a).
Shown in (b) and (C).

(2) Configuration of Image Processing Apparatus The configuration of the image processing apparatus 400 will be explained with reference to FIG.

The image processing device 400 is a CC in the image reading device 300.
Black (BK), yellow (Y), and
It is converted into magenta (M) and cyan (C) recording signals. Furthermore, the RGB image data given from the PDL controller 200 described above is similarly black (B
K), yellow (Y), magenta (M), and cyan (C). Here, the mode in which image signals are input from the image reading device 300 is called a copying machine mode, and the mode in which RGB image data is input from the PDL controller 200 is called a graphics mode.

The image processing device 400 includes CCDs 7r, 7g, and 7b.
The color gradation data obtained by A/D converting the output signal of 8 bits is input, and the optical illumination unevenness, CC
A shading correction circuit 401 that performs correction for variations in sensitivity of internal terminal elements of D7r, 7g, and 7b.
and a multiplexer 402 that selectively outputs either the color gradation data output from the shading correction circuit 401 or the color gradation data (RGB image data) output from the PDL controller 200 according to the above-described mode.
and the 8-bit data output from the multiplexer 402 (
A γ correction circuit 403 inputs color gradation data), changes the gradation according to the characteristics of the photoconductor, and outputs it as 6-bit data;
The 6-bint gradation data representing the gradation of green (G) and blue (B) is converted into complementary colors cyan (C) and magenta (M).
A complementary color generation circuit 405 converts into yellow (Y) gradation data (6 bits), and a masking processing circuit 406 performs predetermined masking processing on each Y, M, and C gradation data output from the complementary color generation circuit 405. , a UCR processing/black generation circuit 407 that inputs Y, M, and C gradation data after masking processing and executes UCR processing and black generation processing;
Y, M, output from the UCR processing/black generation circuit 407
Convert each 6-bit gradation data of C1 and BK into 3-bit floor 3-cycle data YLMI, CL, and BKI,
It is composed of a gradation processing circuit 408 that outputs output to the laser drive processing section 502 inside the multivalued color laser printer 500, and a synchronization control circuit 409 for synchronizing each circuit of the image processing apparatus 400.

Although details will be omitted, the γ correction circuit 403 has a configuration in which the gradation can be arbitrarily changed using an operation button on the console 701.

Further, as an algorithm used in the gradation processing circuit 408, a multi-value dither method, a multi-value error diffusion method, etc. can be applied. For example, a dither matrix of the multi-value dither method is
x3, multilevel color laser printer 500
The number of gradations is the product of 3×3 area gradations and 3-bit (that is, 8 steps) multilevel level, and is 3×3×8=72 (gradations).

Next, the processing of the masking processing circuit 406 and the UCR processing/black generation circuit 407 will be explained.

Generally, the arithmetic expression for the masking process of the masking process circuit 406 is as follows: Y, , M, C8: Data before masking process Y O,M
O, CO: Data after masking processing Also, the arithmetic expression for UCR processing of the UCR processing/black generation circuit 407 is generally expressed as follows.

Therefore, in this embodiment, new coefficients are obtained using the product of both coefficients from these equations.

In this embodiment, a new coefficient (al+'', etc.) that performs this masking process and UCR process simultaneously is calculated and obtained in advance.
Furthermore, using the new coefficients, the masking processing circuit 40
6 scheduled input values Y, M, , Ci (6 bints each)
The output value corresponding to (Y.

etc.: A value that is the calculation result of the OCR processing/black generation circuit 407) is obtained and stored in a predetermined memory in advance. Therefore, in this embodiment, the masking processing circuit 406 and tJcR
The processing/black generation circuit 407 is composed of a set of ROM, and the data at the address specified by the inputs Y, M, and C of the masking processing circuit 406 is processed by the UCR processing/black generation circuit 40.
It is given as the output of 7.

In addition, for boat fishing, the masking processing circuit 406 performs Y and M according to the characteristics of the spectral reflection wavelength of the toner for forming a recorded image.
, C signals, and the UCR processing/black generation circuit 407 performs correction for color balance in overlapping toners of each color. UCR processing/black generation circuit 4
07, black component data BK is generated by combining the input three color data of Y, M, and C, and the output Y,
The M and C color component data are corrected to values obtained by subtracting the black component data BK.

In the above configuration, the T correction circuit 403 executes processing based on the T correction conversion graph shown in FIG. 15, and the complementary color generation circuit 405 executes the complementary color processing shown in FIGS. Suppose that processing is executed based on the generation conversion graph, and then the masking processing circuit 406 and the OCR processing/black generation circuit 407 execute processing based on the following equation.
The RGB image data shown in FIGS. 12(a), (b), and (C) includes a T correction circuit 403, a complementary color generation circuit 405,
17(a), (b), (C),
It is converted as shown in (d).

Furthermore, when the gradation processing circuit 408 uses the Bayer type 3×3 multi-level dither matrix shown in FIG. 18, Y in FIGS. ,M,C,
The data for BK are shown in Figure 19 (a), (b), and (C), respectively.
), converted into the data shown in (d).

For comparison, when data without anti-aliasing processing (data in FIGS. 13(a), (b), and (C)) is processed by the image processing device 400, the 20th
Figures (a), (b), (c), and (d) were transformed as shown.

■Configuration of multivalued color laser printer First, the 21st
The schematic configuration of the multivalued color laser printer 500 will be described with reference to the control block diagram shown in the figure.

A photoreceptor development processing unit 501 uniformly charges the surface of a photoreceptor tram (described later), exposes the charged surface to a laser beam to form a latent image, develops the latent image with toner, and transfers it to recording paper. The details will be explained later, but the development and development of BK data is
A black developing/transfer section 501bk that performs transfer, a cyan developing/transfer section 501C that develops and transfers C data,
Cyan development/transfer section 501 that develops/transfers M data
m, and a cyan developing/transfer section 501y that develops and transfers Y data.

The laser drive processing unit 502 includes the image processing device 4 described above.
The laser beam is output by inputting the 3-bit data of Y, M, C, and BK output from 00 (in this case, image density data). Input buffer memory 503y, 503m
, 503c, and a laser diode-F 504 that outputs laser beams corresponding to Y, M, C, and BK, respectively.
Drivers 505y, 505m, and 505c drive the laser diodes 504y, 504m, 504c, and 504bk, respectively.
, 505bk.

In addition, the black developing/transfer section 5 of the photoreceptor development processing section 501
0 l bk, laser drive processing unit 502 laser diode-F 504 bk, and driver 505bk
The combination is called a black recording unit BKU (see FIG. 22). Similarly, the cyan developing/transfer section 501c,
A combination of a laser diode 504C, a driver 505C1, and a buffer memory 503c is connected to a cyan recording unit CU (see FIG. 22) and a magenta developing/transfer section 501.
m, laser diode 504m, driver 505m,
The combination of the buffer memory 503m is a magenta recording unit (MU) (see FIG. 22), a yellow developing/transfer section 501y, a laser diode 504y, and a driver 5.
05y and the buffer memory 503y is called a yellow recording unit (YU) (see FIG. 22). As shown in the figure, these recording units include a black recording unit 1-BKU, a cyan recording unit CU, a magenta recording unit MU, and a yellow recording unit YU around a conveyor belt 506 that conveys the recording paper from the conveying direction of the recording paper. They are arranged in order.

Due to this arrangement of each recording unit, the laser diode 5 for black exposure starts exposure first.
04bk, and the laser diode 504:Y for yellow exposure starts exposure last. Therefore, there is a time difference in the order of exposure start between each laser diode, and in order to hold the recorded data (output of the image processing device 400) during the time difference, the laser drive processing unit 502 has the three sets of Hanwha memories 503y and 503m described above. , 503
c is provided.

Next, the configuration of the multilevel color laser printer 500 will be specifically explained with reference to FIG. 22.

The multilevel color laser printer 500 includes a transport heald 506 that transports recording paper, and recording units YU, MU, and
Paper cassette 507 containing CU, BKU, and recording paper
a, 507b, and paper feed rollers 508a, 508b that feed the recording paper from 507a, 507b, respectively.
The recording units BKu, CU, M
A fixing roller 510 transports U and YU sequentially and fixes the transferred image onto the recording paper, and the recording paper is transferred to a predetermined ejection section (
(not shown). Here, each recording unit YtJ, MLI, CU, BK
U represents photoreceptor drums 512y, 512m, 512c, 5
12bk, and photoreceptor drums 512y and 512m, respectively.
, a charger 513 that uniformly charges 512C1512bk.
y, 513m, 513C1513bk, and photosensitive drums 512y, 512m, 512C.

512bk (for guiding the laser beam to polygon mirrors 514y, 514m, 514C1514bk and motors 515y, 515m, 515c, 515bk, and electrostatic latent images formed on photoreceptor drums 512y, 512m, 512C1512bk of the respective colors. Toner developing devices 516y, 516m, 5 that perform development using toner
16c, 516bk, and transfer chargers 517y, 517m, 517c, 51 that transfer the developed toner image to recording paper.
7bk, and photoreceptor drums 512y, 512m, after transfer.
Cleaning device 518y, 518m, 518C1518 that removes toner remaining on 512C1512bk
It consists of bk. In addition, 519y, 519m, 51
9c and 519bk are photosensitive drums 512y and 519bk, respectively.
A COD line sensor for reading a predetermined pattern provided on 512m, 512c, and 512bk is shown, and although the details are omitted, the process status of the multivalued color laser printer 500 is detected by this.

In the above configuration, the operations of the yellow recording unit YU will be explained using exposure, development, and transfer as examples.

FIGS. 23(a) and 23(b) show the configuration of the exposure system of the yellow recording unit YU. In the figure, a laser beam emitted from a laser diode 504y is reflected by a polygon mirror 514y, passes through an f-theta lens 520y, is further reflected by mirrors 521y and 522y, passes through a dustproof glass 523y, and hits a photoreceptor drum 512y. irradiated. At this time, the laser beam is
4y is driven to rotate at a constant speed by the motor 515y, so it moves in the direction along the axis of the photosensitive tram 512y (main scanning direction). Furthermore, in this embodiment, a photosensor 524y is provided to detect the base point for tracking the scanning position of the main scan, so that the laser beam at the non-exposed position is detected. Since the laser diode 504y is activated to emit light based on the recorded data (3-bit data from the image processing device 400), multivalue exposure corresponding to the recorded data is applied to the photoreceptor drum 504y.
performed on the surface of The surface of the photosensitive drum 504y is uniformly charged in advance by the charger 513y as described above, and an electrostatic latent image corresponding to the original image is formed by the exposure. The electrostatic latent image is developed by a yellow developing device 516y to become a yellow toner image. This toner image is transferred from the cassette 507a (or 507b) to the paper feed roller 508a (or 5
08b), and is transferred by the registration rollers 509 to the recording paper conveyed by the conveyor belt 506 in synchronization with the formation of the black recording unit (BKU) toner image.

The other recording units BKU, CU, and MU have similar configurations and perform similar operations, but the black recording unit BKU is equipped with a black toner developing device 516bk and forms and transfers a blank toner image, and the cyan recording unit C
U is equipped with a cyan toner developing device 516C, which forms and transfers a cyan toner image, and a magenta recording unit M
U includes a magenta toner developing device 516m, which forms and transfers a magenta toner image.

■Driver multi-value drive driver 505 ”j, 505m, 505C1505b
are Y, M, and C sent from the image processing device 40゛0.
, BK, the corresponding laser diodes 504y, 504m, 504c, 504bk
It performs control for multivalue driving, and power modulation, pulse width modulation, etc. are generally used as driving methods.

Hereinafter, the multivalue drive by power modulation which is used in this embodiment will be explained in detail with reference to FIGS. 24(a), 24(a), 24(d). In addition, drivers 505y, 505m, 505
c, 505b, and laser diode 504y, 5
Since 04m and 504C1504bk each have the same configuration, the driver 505y and laser diode 504y will be explained here as an example.

As shown in FIG. 24(a), the driver 505y turns the laser diode 504y on and off based on a predetermined LD drive clock.
n10ff circuit 550 and 3-focus image density data (
Here, the D/A converts Y data) into an analog signal.
A current (LD drive current) Id that drives the laser diode 504y by inputting the analog signal based on the image density value from the D/A converter 551 and the analog signal based on the image density value.
and a constant current circuit 552 that supplies the laser diode on10ff circuit 550 with the constant current circuit 552.

Here, the LD drive clock is On “0°” at 1°°.
As shown in FIG. 24(b), the laser diode on10ff circuit 550 turns off the laser diode 5o4y accordingly. Furthermore, since there is a proportional relationship between the LD drive current 1d and the laser beam power, by generating the LD drive current Id based on the image density data value, the laser beam power output corresponding to the image density data value can be obtained. It turns out. For example, as shown in FIG. 24(b), when the image density data value is "4" (data N-1 in the figure), the corresponding LD drive current 1d is supplied by the constant current circuit 552, The laser beam power of the laser diode 504y is level 4. Also, the image density data value is “7”.
In the case of (data N in the figure), the corresponding LD drive current 1d is supplied by the constant current circuit 552, and the laser beam power of the laser diode 504y becomes level 7.

Next, with reference to FIG. 24(C), a specific circuit configuration of the laser diode on10ff circuit 550, the D/A converter 551, and the constant current circuit 552 will be shown. The laser diode on10ff circuit 550 includes TTL inverters 553 and 554, differential switching circuits 555 and 556 that perform an onloff toggle operation, and a VG
1>VC2, the differential switching circuit 555 is on, the differential switching circuit 556 is off, V
When GI<VC2, the differential switching circuit 555 is turned off and the differential switching circuit 556 is turned on.It is composed of resistors R2 and R3 forming a voltage dividing circuit that generates VC,2 which satisfies the condition that the differential switching circuit 555 is turned off and the differential switching circuit 556 is turned on. . Therefore, when the LD drive clock is "1", the output of the inverter 554 generates VGI, the above condition (VGI>VO2) is satisfied, the differential switching circuit 555 is turned on, and the differential switching circuit 556 is turned on. offL, the laser diode 504y is turned on. Conversely, when the LD drive clock is "0", there is no output from the inverter 554, so the above condition (VGI<VO2) is satisfied, and the differential switching circuit 555 is off, the differential switching circuit 556 is on, and the laser diode 504y is turned off.
f.

The D/A converter 551 includes a latch 557 that latches input image density data while the LD drive clock is "1", a V rmf generator 558 that provides a maximum output value V ref, and a V rmf generator 558 that outputs the image density data and maximum output. Value V ra
3-bit D outputting analog data Vd based on f
/A converter 559. Furthermore, here V
The relationship between d, image density data, and maximum output value V raf is expressed by the following equation.

The constant current circuit 552 includes the laser diode 504 in the laser diode ON10ff circuit 550 as described above.
y current, and the transistor 560
and resistors R4 and Rs. The output Vd from D/A converter 551 is applied to the gate of transistor 560 to determine the voltage applied to resistor R4. In other words, since the current flowing through the resistor R4 is approximately equal to the collector current of the transistor 560, the current Id flowing through the laser diode 504y is controlled by Vd.

FIG. 24(d) shows the output of the aforementioned launch 557, VG
5 is a timing chart showing the relationship between I, Vd, and Id. Here, Vd is Vref
x takes eight levels from O/7 to 7/7, and Id indicates eight levels from 10 to I7 based on this VdO value. The laser diode 504y has eight levels of this Id (1, -level 0, I, -levelt...I7-
level 7), the second
A latent image as shown in FIG. 5 is formed.

When the edge pixels are divided into a predetermined group of straight lines, as explained in the above section ∎Anti-aliasing processing, whether or not there is a favorable change between the vector data and the predetermined group of straight lines, and the proximity of the pixels of the edge based on the type of edge. In the image forming system applying the anti-aliasing method to obtain the effective area ratio, the toner image shown in FIG. 26 is finally recorded on the pentagon ABCDE shown in FIG. 10(a) by the above-described configuration and operation. Formed on paper. - Considering that the resolution of a laser printer for boat fishing is 240 dpi to 400 dpi, the density of the edges of the figure becomes visually lighter due to the anti-aliasing process. Figure 27 shows pentagon ABC without anti-aliasing processing.
FIG. 26 shows a toner image of DH (toner image of the present invention)
As is clear from a comparison between FIG. 27 and FIG. 27, the anti-aliasing process visually smooths out the jagged portions (aliases) on the stairs that appear in the hatched areas of the figure.

Further, in this embodiment, multi-value driving using power modulation is applied, but it goes without saying that similar effects can be obtained by using multi-value driving using pulse width modulation.

For reference, FIG. 28 shows the change in latent image form depending on the level of pulse width modulation, and also shows the toner image when pulse width modulation is applied to the pentagon ABCDE shown in FIG. 10(a). It is shown in FIG.

(2) Operation of graphic processing apparatus according to non-embodiment The operator uses the digitizer 700 to input predetermined coordinates to designate an area in which image editing processing is to be performed. The data indicating the area specified by the digitizer 700 is sent to the PDL controller 2 as hefter data.
Output as 00.

The hector data input to the PDL controller 200 is converted into raster data while performing anti-aliasing processing, and the raster data is sent to the image processing device 4.
Output to 00.

The image processing device 400 calculates the area data output from the PDL controller 200 and the image data from the image reading device 300, and executes editing processing based on the calculation results.

After the editing process is completed, the image processing device 400 outputs the multivalued image data to the multivalued color laser printer 500, and the multivalued color laser printer 500 executes the printing process based on the multivalued image data. .

The editing function processing according to this embodiment will be explained in more detail by taking intra-area deletion as an example.

FIG. 30 shows the density of image data read by the image reading device 500, here the maximum density (255).

FIG. 31 shows the result of filling in area data using 3×3 subpixels.

For example, when the uniform averaging method described in the section (2) about anti-aliasing processing is executed as anti-aliasing processing, the contribution rate of each pixel becomes as shown in FIG. 32. To execute intra-area deletion, it is sufficient to multiply the image data by a number obtained by subtracting the above contribution rate from 1. The results are shown in FIG.

Incidentally, if the region data is processed in binary without performing anti-aliasing processing, X7, X, . The contribution rates of each pixel are both 1, and as a result, aliasing occurs.

〔Effect of the invention〕

As explained above, according to the graphic processing device of the present invention, when performing image processing on the area specified by the coordinate specifying means on the image data read by the image reading device, the boundary portion of the area is Since the image data is output from the printer after performing anti-aliasing processing, it is possible to smoothly express jaggedness (aliasing) that occurs at the boundary of the designated area by area data, and improve the quality of the output image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a graphic processing device according to the present invention, FIGS. 2(a) and (b) are explanatory diagrams showing conventional antialiasing processing, and FIGS. 3(a) and (b) are uniform An explanatory diagram showing antialiasing processing using the averaging method,
Figures 4 (a) and (b) are explanatory diagrams showing anti-aliasing processing using the weighted averaging method, and Figures 5 (a) and (b).
), (C), and (d) are explanatory diagrams showing examples of filters used in the weighted averaging method. Fig. 7 is an explanatory diagram showing a convolution method with 3 x 3 pixel reference. Fig. 1 (a) Figure 8 is a block diagram showing the configuration of the PDL controller shown in Figure 1, and Figure 9(a) shows the operation of the PDL controller. Flowchart, FIG. 9(b) is an explanatory diagram showing path filling processing, FIG. 9(C) is a flowchart showing anti-aliasing processing of the present invention, 10th
Figures (a) and (b) are explanatory diagrams showing linear vector division of a figure, Figure 11 is an explanatory diagram showing the return area ratio after performing anti-aliasing processing, and Figures 12 (a), (b), ( C
) is the RG stored in the plain memory section of the page memory.
Explanatory diagrams showing B image data, FIGS. 13(a), (b), and (C) are R images stored in the plain memory section of the page memory when anti-aliasing processing is not performed.
An explanatory diagram showing GB image data, Fig. 14 is an explanatory diagram showing the configuration of the image processing device, Fig. 15 is an explanatory diagram showing a conversion graph for T correction of the T correction circuit, Figs. 16 (a) and (b).
, (C) is an explanatory diagram showing a conversion graph for complementary color generation used in the complementary color generation circuit, and FIGS.
) is an explanatory diagram showing the state in which the RGB image data shown in FIGS. 12(a), (b), and (C) is output from the UCR processing/black generation circuit, and FIG. 18 is a Heyer type 3×3 An explanatory diagram showing the multivalued dither matrix of FIG.
, (b) An explanatory diagram showing the state in which the Y, M, and CXBK data are converted by the gradation processing circuit, Fig. 20 (a), (
b), (C), and (d) are shown in Fig. 13 (a), (b), and (c).
) (D Cheetara An explanatory diagram showing the state of processing by the image processing device, Fig. 21 is a control block diagram showing a multi-value color laser printer, and Fig. 22 is a multi-value color laser printer.
Explanatory diagram showing the configuration of a laser printer, Fig. 23 (a
), (b) are explanatory diagrams showing the configuration of the exposure system of the yellow recording unit, FIGS. Figure 25 is an explanatory diagram showing the state of the latent image depending on the power modulation level.
FIG. 6 is an explanatory diagram showing the final toner image of the pentagon ABCDH shown in FIG. is an explanatory diagram showing the state of the latent image depending on the level of pulse width modulation, and Fig. 29 is Fig. 10 (a).
An explanatory diagram showing a toner image when pulse width modulation is applied to the pentagon ABCDE shown in FIG. 32 is an explanatory diagram showing the result of executing the filling process using sub-pixels of No. 3; FIG. 32 is an explanatory diagram showing the contribution rate of each pixel shown in FIG. 31;
Fig. 33 is an explanatory diagram showing the result of multiplying image data by the number obtained by subtracting the contribution rate shown in Fig. 32 from 1, and Figs. 34 to 36 are editing operations for deletion within a specified area in a conventional digital copying machine. FIG. Explanation of symbols 10CI - host computer 200 - PD L controller 300 - multivalued color laser printer 400 - image processing device 403 - high resolution circuit 451 - counters 452 to 455 - line memory 456 - line memory control Circuit 464 - arithmetic circuit 470 - shift register 500 - image reading device 600 - system control unit 700 - digitizer

Claims (1)

[Scope of Claims] Reading means for reading multivalued image data from a document; coordinate input means for specifying an area in which image editing processing is to be performed in the image data read by the reading means; anti-aliasing processing means for performing anti-aliasing processing on the boundaries of regions; image processing means for calculating the image data and region data; and converting the data image-processed by the image processing means into multivalued data and outputting the multivalued data. A graphic processing device comprising: graphic output means.