JPH04207260A - Figure output device - Google Patents

Abstract

PURPOSE:To assure the continuity of images and to enhance an antialiasing effect by selectively using a pulse width modulation system and a power modulation system in accordance with the information on the coordinates at the end points of picture elements and the number of vectors in the picture elements. CONSTITUTION:A PDL controller 200 and a system control section 600 cooperatively drive an image processor 400 and an image reader 300 under the control of a host computer 100. Namely, the end point of the vector image is decided and the number of vectors existing in the picture elements is decided. The information on the vector intersection in the picture element is then detected. The pulse width (vertically long dot diameter) modulation writing section and power (horizontally long dot diameter) modulation writing section of a laser writing section 110 which outputs the image information are selectively controlled from the various results thereof. The continuity of the images is assured and the zigzaging (aliasing) at the end edges of the output images is removed by this constitution.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a graphic output device that performs anti-aliasing processing to remove jagged edges of an output image, and more specifically, Focusing on the end points,
The present invention relates to a graphic output device that selects an appropriate modulation method based on information such as the coordinates of the end points to improve continuity with adjacent pixels.

[Conventional technology]

In the field of computer graphics, when displaying an image on a CRT, which is an output medium, a technique called anti-aliasing processing is used to make the displayed image more beautiful.

This process applies brightness modulation to the jagged parts (called aliases) on the stairs as shown in Figure 29(a),
This visually smooths the displayed image as shown in FIG. 29 (b).

In addition, there is a multilevel color laser printer as a method for outputting data after anti-aliasing processing, and the power modulation method and pulse width modulation method are generally used as driving methods.

[Problem to be solved by the invention]

However, in a multilevel printer that forms an electrostatic latent image using a power modulation method, the pixel latent image of the figure edge extending in the sub-scanning direction is separated from the upper and lower pixel latent images, as shown in FIG. 30(a). Put it away.

In addition, in a multilevel printer that forms an electrostatic latent image using a pulse width modulation method, as shown in FIG. As shown in Figure 30 (C), the beam is irradiated far away from the end point, and the continuity with adjacent pixels is lost, so the continuity of the entire image is lost.
There is a problem in that the effect of anti-aliasing processing is diminished.

The present invention has been made in view of the above, and aims to ensure continuity of images and enhance the effect of anti-aliasing processing.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an anti-aliasing processing means that smoothly expresses jagged edges (aliases) of a vector image, and a pulse that outputs image data subjected to anti-aliasing processing by the anti-aliasing processing means. A graphic output device comprising an image output means having a width modulation writing section and a power modulation writing section, an end point determination means for determining an end point of the vector image, and a vector number for determining the number of vectors existing in a pixel. a determining means, a cross information detecting means for detecting cross information in pixels of each vector, and a pulse width modulation writing section and a power modulation writing section based on the results of the end point determining means, the vector number determining means, and the cross information detecting means. The present invention provides a graphic output device comprising a control means for selectively controlling the embedding section.

Further, a first calculation means for calculating a pulse position from the coordinates of the end point, and a storage means for storing pulse position information and pulse width information calculated by the first calculation means;
The present invention provides a graphic output device comprising a second calculation means for calculating a more appropriate area ratio from each piece of information and the area ratio stored in the storage means.

[For production]

The graphic output device of the present invention has coordinates of an end point in a pixel,
Based on information such as the number of vectors existing in a pixel, a pulse width modulation method (vertical dot diameter) and a power modulation method (horizontal dot diameter) are selectively used.

〔Example〕

Hereinafter, one embodiment of the graphic output device of the present invention will be described based on the drawings. Configuration of a color laser printer (configuration and operation of the developing section of a multivalued color laser printer) ■Details will be explained in the order of multivalued drive of the driver.

(1) Outline of the present invention FIG. 1(a) is a schematic explanatory diagram showing the peripheral portion of a laser writing section in a graphic output device according to the present invention.

In the present invention, a plurality of information signals are input to a laser writing section 110 using a device as illustrated, and the laser writing section 110
controls the laser diode 111 and switches its output method.

Further, this device requires the following information to be input: 1, power data nn 2, pulse width data mm 3, and pulse position data xx.

The above three types of data are each written independently in the laser writing section 110.
control.

FIG. 1(b) shows the state of latent image formation based on pulse width data mm (where XX=O5nn=7), and FIG. 1(C) shows the state of latent image formation based on pulse position data XX. (however, mm=1, nn=7), Fig. 1 (d
) indicates the formation state of a latent image based on power data nn (however, mm=7, x x -0).

Next, an outline of the antialiasing process with elevated end points according to the present invention will be explained.

An end point means that two or more hectares exist within one pixel. In this embodiment, we will take up the case of 2 vectors, and for 3 hectares or more, the fixed value will be treated as the area ratio of the pixel.

Therefore, examples of classification are shown in FIGS. 1(e) to (0) by focusing on which side the 2 hectares intersect with each pixel.

FIG. 1(e) shows the side numbers of pixels.

Written to the right of each pixel is the intersecting side number.

Figures 1(f) to 1(h) are shown in Figure 1(e).
, A group that contacts 3 on two sides or 2.4 on every side,
FIG. 1(i) to FIG. 1(0) are B groups other than the above A group.

If the vector is a left edge, set it to 2, if it is a right edge, set it to 4.

Hereinafter, a detailed description will be given of the A group and the B group.

The i, A group pulse width is determined by the percentage of filled area, and the pulse position is determined by the calculation result obtained by rounding the X coordinate of the end point T.

If the system has eight patterns of position control capability as shown in Figure 1 (C), refer to Figure 1 (C) and determine which of the 1/8 pitches the X coordinate of the end point T corresponds to. demand. The position L dwn is t, +w, = INT (8x + 0.5)
It can be obtained by the formula 1.

In each case, □ is tdw, , l in the table of Fig. 25, which will be described later.
"" Make it correspond to L dwnt.

However, if the X coordinate of the end point T is large and the area ratio is also large, tdwn7 in FIG. can't get it.

Therefore, FIG. 1(b) shows a possible state (conversion table) when the two methods are used together in the above situation. Therefore, the area ratio (Here, it is assumed that a level corresponding to a pulse width of 3 is obtained through anti-aliasing processing.The method of calculating the area ratio will be described later, but for example, the method using submatrix division, the simple area ratio neighbor method) It is necessary to change the pulse position to satisfy the following method. That is, in FIG. 1(q), the state is changed from point a to a point with a pulse width of 3 and a maximum Ldw.

By the above operation, an output as shown in FIG. 1(r) is obtained.

ii. Group B In the case of group B, it is necessary to determine the left and right edges, but this information is stored in advance in the filling process shown in FIG. 8(a), which will be described later.

1) For the left edge, control is performed at a level 7 pulse position and at a pulse width according to the area ratio.

2) In the case of the right edge, it follows the above A group (however, the difference from the above A group is that in this process, f and dwnl are always taken, whereas the A group does not necessarily take t.77). ) and then performs the conversion in the conversion table.

By performing the above operations, end point processing according to the present invention can be realized.

■Schematic configuration of image forming system The image forming system of this embodiment uses a page description language (page description language) output from DTP (desk top publishing).
Page Description Language
This configuration allows 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 image forming system of this embodiment will be described below with reference to the first E(S).

The image forming system includes a host computer 100 that creates a document written in PDL language (Postscript language is used in this embodiment);
A PDL controller (the anti-aliasing processing of the present invention) that applies anti-aliasing processing to the incoming PDL language sent page by page from Bag W) 200
an image reading device 300 that reads image information through an optical system unit; and an image processing device 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). device 400, and a multivalued color laser printer 5 that prints multivalued image data output by the image processing device 400.
00, PDL controller 200, and image reading device 3
00, an image processing device 400, and a system control unit 600 that controls a multivalued color laser printer 500.

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

i, Uniform averaging method ii, Weighting is the averaging method ji, convolution integral method Each of the above methods will be explained in turn.

i, Uniform averaging method The uniform averaging method calculates each pixel by 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 sub-pixels. Figure 2 (a), (
Anti-aliasing processing using the uniform averaging method will be specifically explained with reference to b).

If the edge of the image is over a certain pixel (here, the image is connected to the bottom right of the diagonal line),
When anti-aliasing processing is not performed, the same figure (a)
), the brightness kid of this pixel is the highest brightness of the gradation that can be displayed (for example, for 256 gradations, kid=
255) is assigned. N=M= for this pixel
When performing anti-aliasing processing using the uniform averaging method of 7*, as shown in FIG.
The image is divided into 7 sub-pixels and the number of sub-pixels covered by the image is counted. The count number (28) is 1
The maximum brightness (255) is divided by the total number of sub-vixels in the pixel (49 in this case) and normalized (averaged), and then 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, the weighted averaging method assigns a weight to each subpixel, and the brightness of that subpixel (kid) is calculated based on which subpixel the image covers. The impact is different. Note that the weight at this time is given using a filter.

Referring to Figures 3(a) and (b), an example is shown in which the same image data as in Figure 2(a) is weighted using the same dividing method (N=M=7) and the averaging method. show.

FIG. 3(a) shows a filter (here, conefi
lter), and the corresponding sub-pixel is given the same weight as this characteristic. For example, the weight of the upper right corner subpixel is 2. When an image is applied to each subpixel, the weight value given by the filter characteristics becomes the count value of that subpixel. FIG. 6B shows the display pattern of the image changed depending on the weight of the sub-pixels. In this case, if we count the weighted sub-vixels of the image, we get 1
It becomes 99. 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. The filters shown in Fig. 4 (a), (b),
Filters shown in (C) and (d) are known.

ji1 Convolutional Integral Method The convolutional integral method is a method that also refers to the appearance of surrounding pixels when determining the brightness of one pixel. That is, the area around one pixel whose brightness is to be determined is N
'XN' pixel, equal-averaging or weighting is considered to correspond to the pixel of the averaging method. FIG. 5 shows the convolution method with 3×3 pixel references. In this figure, the pixel whose brightness is to be determined is indicated at 51.

The image continues below and to the right of the diagonal line, and the subpixels painted black are the subpixels 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 belongs to the language genre of page description languages, and is a form that describes the contents of a single document, including the text (letter part), graphics, and their arrangement and appearance. It is a programming language for writing, and in such systems, vector fonts are used as character fonts. Therefore, even when characters are scaled, the print quality can be significantly improved compared to systems that use bitmap fonts (for example, conventional word processors, etc.). It has the advantage that it can be printed with a mixture of

However, according to the conventional anti-aliasing processing method and its device, one pixel is divided into a plurality of sub-pixels (for example, 49 sub-pixels), and the number of filled-in sub-pixels is counted to calculate the area. Since the ratio (brightness) is calculated, it takes time to calculate the area ratio, which poses a problem in that it becomes an impediment to improving 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.

iv. Method for obtaining approximate area ratio of edge pixels This anti-aliasing processing method determines whether or not there is an intersection between hector data and a predetermined group of straight lines when edge pixels are divided by a predetermined group of straight lines, and Based on the type, an approximate area ratio of the edge pixel is obtained. Below, Figure 6 (
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).

Straight line Ll given by vector data (hereinafter referred to as vector straight line L1) and each line in the sub-scanning direction y)
' 0+ )TI+ )+2 intersect at the intersection Xo+X++Xz, as shown in FIG.
From O+ Y O) + (X l+ yI), the following formula (
1).

On the other hand, focusing on the pixel P, a new x'y' coordinate system is set, and as shown in FIG. 6(b), the pixel P is
-+, lz, lx, l-, is, lb, 17. im 8
Divide by two straight lines (hereinafter referred to as dividing straight lines). Here, the equations of each straight line are expressed by the following equations (3) to 00).

Divided straight line 1! +: x = O------(3)
I! , z:χ=1/3 ------- (4)13
: x = 2 / 3 −−−−−− (5)! ! ,
4: x=1 --111・-(6) f 5: y=
O------(7)1! , b: y=1/3-
−・−(8)17 :y=2/3 ・−−−−−(
9) j2e: y = 1 −1−−・−0
0) Also, assuming that the equation of the vector straight line L1 obtained using the above formula (1) is y - (1/3) x 0 (7/6) - (2), this vector straight line L1 and Dividing straight line 1+, lz, is, la, 15°i,, p, which divides pixel P
The coordinates of the intersection with i are shown in the following table.

Here, X'' and y of pixel P in the χ'' y゛ coordinate system
The range of o is 0 ≦ On the contrary, within the range of this pixel P, the above three dividing straight lines 13
．． Is,! ! , s, the equation of a vector line that intersects only with
Then, the coordinates of intersection A are (1/3<x”≦2/3.y”-1
) The coordinates of the intersection B always pass through the range (x'=1.2/3<y'<1). Therefore, the area ratios of pixels P divided by vector straight lines that have intersections with only the three dividing straight lines 1z, 14, and 18 have close values; in other words, the area ratios of pixels P that have intersections with a predetermined group of dividing straight lines When the group of vector straight lines is set as one set, the area ratio of the pixels P divided by the group of vector straight lines in the set indicates a similar area ratio within a predetermined range. Therefore, the vector line and the dividing line 1+, 12z, ! ! , 3.14. ls, R
The individual area ratios of the sets classified based on the intersection information with h and I17.1m 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, as shown in FIG. 6(d), a LUT (Lookllp Table) consisting of intersection information, edge information, and approximate area ratio is created. After that, when performing anti-aliasing processing, instead of performing sub-vixel division and calculating the area ratio of edge pixels, the corresponding approximate area ratio is input from the LUT based on the intersection information and edge information. The output of the edge pixels is adjusted accordingly.

In the LUT shown in FIG. 6(d), the edge information flag indicates a left edge when the left edge flag = 1 and the right edge flag = 0, and indicates a right edge when the left edge flag is -0 and the right edge flag is -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+, lt.

...I! , ll and the vector straight line intersect (that is, there is an intersection). The same figure (e
), and the data D1 also includes information on the approximate area ratio of the shaded area shown in FIG. 2(e). Similarly, LUT
(Figure 3) shows a straight line that can be considered under the conditions of data D2, and data D2 includes information about the approximate area ratio of the shaded area shown in figure (f). Therefore, for example,
When calculating the area ratio of the hector straight line in FIG.・・・・・・! 8, and then determine whether the edge is a left edge or a right edge using edge information determined by the PDL specifications. Based on these intersection information and edge information, LUT
Obtain the applicable approximate area ratio from .

■Configuration and operation of PDL controller FIG. 7(a) shows the configuration of the PDL controller 200.
A receiving device 201 that receives the L language, a CPU 202 that performs storage control and anti-aliasing processing for the PDL language received by the receiving device 201, an internal system hash 203, and a receiving device 2 via the internal system path 203.
RAM 204 that stores the PDL language to be transferred from 01
RA that stores anti-aliasing programs, etc.
M204, a page memory 206 that stores multivalued RGB image data subjected to anti-aliasing processing, and a transmitter W 207 that transfers the RGB image data stored in the page memory 206 to the image processing device 400;
I10 device 20 that performs transmission and reception with the system control unit 600
It consists of 8.

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, you will receive one page of PDL language,
When stored in the RAM 204, the graphic elements in the RAM 204 are subjected to an anti-aliasing processing method and multivalued RGB
Image data is stored in the plain memory section of the page memory 206 (the page memory 206 has R, G, and B plain memory sections 206a, as shown in FIG. 7(b),
).

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 FIG.

FIG. 8(a) shows a flowchart of the 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 converts it into three-color images of red (R), green (G), and blue (B). Expand to image.

In the PDL language, graphics and characters are all described using vector 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 text elements).

First, when the FDP 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 linear 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 step 3, filling in with scanning lines is performed while updating the X coordinate one by one. For example, when performing the path filling process shown in FIG.
(XIX shown in Figure 8(b))
z X3 Xa) 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 the
The X coordinates crossing 1 Ayc are not necessarily registered in descending order. For example, in process 1, if a straight line element passing through scanning line yc and X3 in FIG. 8(b) is processed first, be registered first. Therefore, A.E.
After registering T, 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). Anti-aliasing processing is achieved in this filling processing by adjusting the density and brightness of the pixel in the cut and cut portions according to the approximate area ratio.

Then, remove the processed edge from the AET, update the scanline (update the Repeat the process.

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, (2) the end point processing of the graphic output device according to the present invention, which has been described in detail, will be explained based on the flowchart of FIG. 8(C).

First, it is determined whether two vectors exist within one pixel (step 5301). As a result, if it is determined that 2 hectares do not exist in one pixel, the fixed value is treated as the area ratio of the pixel (step S318). On the other hand, if it is determined that two vectors exist within one pixel, it is then determined whether or not an end point exists (step 5).
302). As a result, if it is determined that there is no end point, the series of processing ends. On the other hand, if it is determined that an endpoint exists, find the intersection information between each vector and the pixel edge (
Step 5303). After that, the obtained intersection information is the intersecting sequence number 11.33 shown in Figures 1) to (5).
．． 24 (step 3304).
). As a result, if it is determined that this applies, the area ratio calculation is executed based on the above information (step 5305), and tdw is calculated from the X coordinate of the end point T. (Step 5306
). Thereafter, referring to the conversion table shown in FIG. 1 (9) (step 5307), it is determined whether or not the area ratio can be secured (step 330B). As a result, if it is determined that the area ratio cannot be secured, the pulse position is changed so as to satisfy the area ratio (step 5309).

On the other hand, if it is determined that the area ratio can be secured, the series of operations ends.

Next, in step 5304, the obtained intersection information is the intersecting sequence number 11.
If it is determined that 33.24 does not apply, then it is determined whether or not there is a right edge (step S310). If it is determined that it is a right edge, the pulse position modulation is set to level 0.Step S311L calculates the area ratio (Step 5312L) Determines the pulse width according to the calculated area ratio (Step S313) Control is executed using the pulse width.

In step 5310, if it is determined that the edge is not the right edge, in other words, it is the left edge, the pulse position modulation is set to Ldwr+'7 in step 531.
4) Then, referring to the conversion table shown in FIG. 1(q) (step 5315), it is determined whether the area ratio can be secured (step 5316). As a result, if it is determined that the area ratio cannot be secured, the pulse position is changed to satisfy the area ratio (step 5317).
. On the other hand, if it is determined that the area ratio can be secured,
Finish a series of actions.

After the end point processing, printing processing is executed by appropriately switching the beam power between the power modulation method and the pulse width modulation method using a laser printer to be described later.

0 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.
The three-color image signals read by D7r, 7g, and 7b are converted into black (BK), yellow (Y), magenta (M), and cyan (C) recording signals necessary for recording. Furthermore, the RGB image data given from the PDL controller 200 described above is similarly black (BK).
), yellow (Y), magenta (M), and cyan (
C) into each recording signal. Here, the image reading device W
The mode for inputting image signals from 300 is copy machine mode,
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
a shading correction circuit 401 that performs correction for sensitivity variations, etc. of internal terminal elements of 7r, 7g, and 7b;
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;
A γ correction circuit 40 receives the 8-bit data (color gradation data) output from the multiplexer 402, changes the gradation according to the characteristics of the photoreceptor, and outputs it as 6-bit data.
3, (R) and green (G) output from the γ correction circuit 403.
), 6-bit 7-bit gradation data indicating the gradation of blue (B) is converted into gradation data (6 bits) of the respective complementary colors cyan (C), magenta (M), and yellow (Y). Complementary color generation circuit 405 and Y output from complementary color generation circuit 405
A masking processing circuit 406 performs predetermined masking processing on each gradation data of , M, and C, and a masking processing circuit 406 that performs predetermined masking processing on each gradation data of Y,
A UCR processing/black generation circuit 407 that inputs M and C gradation data and executes UCR processing and black generation processing;
Y, M, C1 output from the R processing/black generation circuit 407
and a gradation processing circuit that converts each 6-bit gradation data of BK into 3-bit gradation data Yl, MLCL, and BKI, and outputs it to the laser drive processing section 502 inside the multi-valued color laser printer 500. 408, and a synchronization control circuit 40 for synchronizing each circuit of the image processing device 400.
It consists of 9.

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 700.

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
x 3, the number of gradations of the multilevel color laser printer 500 is the product of the area gradation of 3 x 3 and the multilevel level of 3 bits (i.e., 8 levels), and 3X3X8 = 72 (gradations). Become.

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,,Ml,,C,: Data before masking process Yo,
M O+ G o: Data after masking processing is used.

Further, the arithmetic expression for UCR processing of the UCR processing/black generation circuit 407 is also generally expressed as follows.

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

In this embodiment, new coefficients (such as "all") that perform this masking process and UCRM process simultaneously are calculated and obtained in advance.
Furthermore, using the new coefficients, the masking processing circuit 40
6 scheduled input values Y,,M,.

Output value (Y0' etc.: O
A value that is the calculation result of the CR 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 U
The CR processing/black generation circuit 407 is composed of a set of ROMs, and the data at the address specified by the inputs Y, M, and C of the masking processing circuit 406 is given as the output of the UCR processing/black generation circuit 407.

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.

■Configuration of multi-value color laser printer (configuration and operation of developing section of multi-value color laser printer) First, with reference to the control block diagram shown in FIG. explain.

A photoreceptor development processing unit 501 uniformly charges the surface of a photoreceptor drum (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,
A magenta developing/transfer section 50 that develops/transfers M data.
1m, and a yellow 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 504y that outputs laser beams corresponding to Y, M, C, and BK, respectively.
Drivers 505y, 505m, and 505C15 drive the laser diodes 504y, 504m, 504c, and 504bk, respectively.
It consists of 05bk.

In addition, the black developing/transfer section 5 of the photoreceptor development processing section 501
01bk, the laser drive processing unit 502, the laser diode 504bk, and the driver 505bk are called a black recording unit BKU (see FIG. 11). Similarly, the combination of cyan developing/transfer section 501C, laser diode 504c, driver 505c, and buffer memory 503c is connected to cyan recording unit CU (
11), a magenta developing/transfer section 501m, a laser diode 504m, a driver 505m, and a buffer memory 503m.
y, laser diode 504y, driver 505
The combination of Y and the buffer memory 503y is called a yellow recording unit (YU) (see FIG. 11). As shown in the figure, these recording units are arranged around a conveyor belt 506 that conveys the recording paper in the order of the conveyance direction of the recording paper: a black recording unit BKU, a cyan recording unit CU, a magenta recording unit MU, and a yellow recording unit YU. It is set up.

Due to this arrangement of each recording unit, the laser diode 5 for black exposure starts exposure first.
04bk, and the laser diode 504y for yellow exposure starts exposure last. Therefore,
There is a time difference in the order of exposure start between each laser diode,
Data recorded during the time difference (output of the image processing device 400)
In order to maintain the information, the laser drive processing unit 502 includes the three sets of haphazard memories 503y, 503m, and 503C described above.
is provided.

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

The multilevel color laser printer 500 includes a conveyance heald 506 that conveys recording paper, and recording units YU, MU, and YU arranged around the conveyance belt 506 as described above.
Paper cassette 507 containing CU, BKU, and recording paper
a, 507b, and paper feed rollers 508a, 508b that feed recording paper from paper feed cassettes 507a, 507b, respectively.
, a registration roller 509 that aligns the recording paper sent out from the paper feed cassettes 507a and 507b, and a conveyor belt 506 that connects the recording unit 1-BKUXCU,
It is composed of a fixing roller 510 that sequentially transports MU and YU and fixes the transferred image on the recording paper, and a paper discharge roller 511 that discharges the recording paper to a predetermined discharge section (not shown). Here, each recording unit YU, MU, CU, BKU
are photoreceptor drums 512"l, 512m, 512c, 5
12bk, and photoreceptor drums 512y and 512m, respectively.
, 512c, and 512bk uniformly.
y, 513m, 513C1513bk, and polygon mirrors 514y, 514m for guiding the laser beam to the photosensitive drums 512y, 512m, 512C1512bk.
, 514C1514bk and motor 515y, 515m
, 515C1515bk, and photosensitive drums 512y, 5
Toner developing devices 516y, 516m, and 516C1516bk that develop the electrostatic latent images formed on 12m, 512c, and 512bk using toners of corresponding colors, and a transfer charger 51 that transfers the developed toner images onto recording paper.
7y, 517m, 517c, 517bk and photosensitive drum 512y, 512m, 512C1512bk after transfer
A cleaning device 518 for removing toner remaining on the
y, 518m, 518C1518bk. In addition, 519y, 519m, 519C1519bk are
Photoreceptor drums 512y, 512m, and 512C1, respectively.
A COD line sensor for reading a predetermined pattern provided on the 512bk is shown, and the details are omitted, but
As a result, the process status of the multivalued color laser printer 500 is detected.

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

FIG. 12(a) shows 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 502y, is further reflected by mirrors 521y and 522y, passes through a dustproof glass 523y, and hits a photosensitive drum 512y. irradiated. At this time, the laser beam is transmitted to the polygon mirror 514.
Since y is rotationally driven at a constant speed by the motor 515y, it moves in the direction along the axis of the photosensitive drum 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 recording data (3-bit data from the image processing device 400), multilevel exposure corresponding to the recording data is performed on the surface of the photoreceptor drum 504y. 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 508
b), and is transferred by registration rollers 509 to the recording paper conveyed by conveyor belt 506 in synchronization with the toner image formation in blank recording unit BKU.

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 black toner image, and the cyan recording unit C
Unit U is equipped with a cyan toner developing device 516C to form and transfer a cyan toner image, and magenta recording unit MU is equipped with a magenta toner developing device 516m to form and transfer a magenta toner image.

■ Multi-value drive drivers 505y, 505m, 505C1505bk drive Y, M, C, and B signals sent from the image processing device 400.
Based on the 3-bit data of K, control is performed to drive the corresponding laser diodes 504y, 504m, and 504C1504bk in multiple values, and power modulation, pulse width modulation, etc. are generally used as the driving method. It is being

Below, power modulation, pulse width modulation, and
Multi-level driving that integrates three pulse position modulation methods will be explained in detail with reference to FIGS. 13 to 28. Furthermore, driver 5
05y, 505m, 505C1505bk and laser diode 504y, 504m, 504C1504
bk have the same configuration, so here, the driver 505y and laser diode 504y will be explained as an example.

The driver 505y, as shown in FIG.
A laser diode on10ff circuit 322 that turns on and off the laser diode 504y based on the D drive clock (LDCK), and a D/A converter 32 that converts 3-bit power data nn into an analog signal.
1 and an analog signal based on the image density value are input from the D/A converter 321, and the laser diode 504y
(constant current circuit 323 that supplies the LD drive current id to the laser diode ON10FF circuit 322)
and a pulse width/position modulation circuit 320 that modulates the pulse width and pulse position of the LD drive clock based on the 3-bit pulse width data mm and pulse position data Xχ.
It consists of

Next, referring to FIG. 14, the laser diode on1
A specific circuit configuration of the 0ff circuit 322, the D/A converter 321, and the constant current circuit 323 is shown. The laser diode on10ff circuit 322 includes TTL inverters 553 and 554, differential switching circuits 555 and 556 that perform onloff toggle operation, and VG 1>V.
When G2, the differential switching circuit 555 is on and the differential switching circuit 556 is off, and when VGI<VG2, the differential switching circuit 555 is off and the differential switching circuit 556 is on. VG to do
It is composed of resistors R, , R, forming a voltage dividing circuit that generates 2. Therefore, when the LD drive clock is "1°", the output of the inverter 554 generates VGI, the above condition (VG 1 > VG2) is satisfied, the differential switching circuit 555 is turned on, and the differential switching circuit 556
is turned off, and 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 (VG
I<VG2), and the differential switching circuit 555
is turned off, and the differential type switching circuit 556 is turned on.
Turn off the laser diode 504y.

The D/A converter 321 includes a latch 557 in which the LD drive clock launches the input image density data while the LD drive clock is "1", a r, f generator 558 that provides the maximum output value V ref, and a generator 558 that outputs the image density data and 3-bit D/A that outputs analog data Vd based on maximum output value ■9.
converter 559. Note that the relationship between Vd, image density data, and maximum output value V ref is expressed by the following equation.

The constant current circuit 323 includes the laser diode 504 in the laser diode ON10ff circuit 322 as described above.
y current, and the transistor 560
and resistors R, , R5. The output Vd from D/A converter 321 is applied to the base of transistor 560 to determine the voltage applied to resistor R4.

In other words, the current flowing through the resistor R4 is the current flowing through the transistor 5.
60, the current Id flowing through the laser diode 504y is controlled by Vd.

Next, the pulse width/position modulation circuit 320 will be explained.

FIG. 15 shows an embodiment of the pulse width/position modulation circuit 320.

330 to 338 are inverter circuits, and 339 to 345 are delay elements, each of which provides a delay time of tl-L7 to LDCK.

346 to 366 are AND circuits, 367 to 371 are buffer circuits, 371 to 380 are OR circuits, and 383
~386.390 are each 8-person selector circuits,
Selection of A, B, and C Select one from D0 to D7 manually and output Y output number. Incidentally, the relationship between A, B, C and selection is shown in FIG.

387 and 388 are selector circuits powered by four people, which select one from D0 to D3 according to selection inputs A and B, and send it to the Y output. Incidentally, the relationship between A, B and selection is shown in FIG.

389 depends on the selection input to the 2-person selector circuit. , DI is selected and sent to the Y output. The relationship between A and selection is shown in FIG.

381.382 is a latch, and the rising edge of the clock input. ～D2 Converts human power and outputs to Q0～Q2. This will convert the data of PWDO~2 and PPDO~2 to LD.
This is to launch and hold at the rising edge of CK, and to prevent abnormal operation even if these human forces change until the next rising edge of LDCK.

Selectors 383 to 389 select pulse position modulated pulses based on selection data of PPDO to 2. Further, the selector 390 selects the pulse position modulated clock of each pulse width according to the selection data of PWDO to 2, and generates LDCKI.

FIG. 19 shows a timing chart of C0 to C7 shown in FIG. 15. In addition, pH ~ P18, P21 is shown in Figure 20.
~P27, P31~P36, P41~P45, P51~
The timing routes of P54, P61 to P63, and P71 to P72 are shown.

In the above configuration, pulse width data 301 to 303 and pulse position data 304 to 306 as image data.
, power data 307 to 309, and an LD drive clock 310 as a clock pulse are added to drive the laser diode 504y. FIG. 21 shows the temporal relationship of each data.

When pulse width data and pulse position data are applied to pulse width/position modulation circuit 320, the desired pulse is
Obtained as I 311, laser diode on10
It is applied to the ff circuit 322.

Laser diode on10ff circuit 322 is LDCK
When l is "1", current Td flows through the laser diode 504y, and conversely, when LDCKI is II 011,
The current 1d for the laser diode 504y is set to O.

Current 1d is generated by constant current circuit 322 as Id313.

On the other hand, the power data PPWDO~2 is input to the D/A converter circuit 321, and the control voltage Vd312 that determines the current 1d of the constant current circuit 323 is input to the D/A converter circuit 321.
21.

In the above embodiment, the power data is 3 bits, so Id takes seven types of data from Id to Id7.

FIG. 22 shows the relationship between PPWDO~2, Id, ~Id7 and the latent image.

Further, FIG. 23 shows the relationship between Id and optical output when the LDCKI is set to a specific value.

Next, the operation of the pulse width/position modulation circuit 320 will be explained.

The pulse width/position modulation circuit 320 has one period T of LDCK.
Divide d (= 1 pixel) into 8 parts and calculate pulse width/from LDCK.
Generate a position modulated LDCK1 pulse.

PWDO~2 determines the pulse width of LDCKl. Second
Figure 4 shows the relationship between PWDO~2 and LDCKl. Further, FIG. 25 shows the relationship between LDCKI and latent image. In order to simplify the explanation, these figures are shown with pulse position modulation fixed (PPDO~2=000).

On the other hand, PPDO~2 similarly divides one cycle Td (=1 pixel) of LDCK into 8, and selects the time from the rise of LDCK (=start point of pixel) to the rise of LDCKI.

Note that since PPDO~2 can be selected independently of PWDO~2, it is also possible to control the rise time of the pulse width modulated pulse.

FIG. 26 and FIG. 27 show the relationship between PPDO~2, LDCKI, and the latent image. Further, FIG. 28 shows an example in which pulse width modulation and position modulation are applied simultaneously.

〔Effect of the invention〕

As explained above, according to the graphic processing device according to the present invention, jaggedness (alias) at the edge portion of a vector image
Anti-aliasing processing means that smoothly expresses
In a graphic output device comprising an image output means having a pulse width modulation writing section and a power modulation writing section outputting image data subjected to anti-aliasing processing by the anti-aliasing processing means, the end points of the vector image are An end point determining means for determining, a vector number determining means for determining the number of vectors present in a pixel, and an intersection information detecting means for detecting intersection information at the pixel of each vector,
control means for selectively controlling the pulse width modulation writing section and the power modulation writing section based on the results of the end point determination means, the vector number determination means, and the intersection information detection means; It is possible to increase the effectiveness of anti-aliasing processing.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1(a) is an explanatory diagram showing the peripheral configuration of the laser writing section, FIG. 1(b) is an explanatory diagram showing the state of formation of a latent image based on pulse width data, FIG. (C) is an explanatory diagram showing the state of latent image formation based on pulse position data, FIG. 1(d) is an explanatory diagram showing the state of latent image formation based on power data, and FIG. 1(e)
~Figure 1 (0) is an explanatory diagram showing an example of classifying two vectors for a pixel based on which side they intersect, and Figure 1 (P) is an explanatory diagram showing an example in which two vectors are classified for a pixel based on which side they intersect. Figure 1 (q) is a table used to find which of the 8 pitches corresponds to the pulse position when changing the pulse position to satisfy the area ratio when the X coordinate of the end point T is large and the area ratio is also large. FIG. 1(r) is an explanatory diagram showing an output example according to the present invention; FIG. 1(S) is an explanatory diagram showing the configuration of the image forming system of this embodiment; FIG. 2(a), 0)) is an explanatory diagram showing anti-aliasing processing using the equalization method, Figures 3 (a) and (b) are explanatory diagrams showing anti-aliasing processing using the weighting averaging method, and Fig. 4 (a) ), (b)
, (C), (d) are explanatory diagrams showing examples of filters used in the weighted averaging method, FIG. 5 is an explanatory diagram showing a convolution method with 3×3 pixel reference, and FIG. (b), (
C), (d), (e), ge) are explanatory diagrams showing anti-aliasing processing to obtain approximate area ratios of edge portion pixels; FIG. 7(a) is an explanatory diagram showing the configuration of a PDL controller;
FIG. 7(b) is an explanatory diagram showing the configuration of the page memory;
FIG. 8(a) is a flowchart showing the operation of the PDL controller, FIG. 8(b) is an explanatory diagram showing path filling processing, and FIG. 8(C) shows three types of information generation methods to implement the present invention. Flowchart, FIG. 9 is an explanatory diagram showing the configuration of the image processing device, FIG. 10 is a multi-value color laser printer, FIG. 11 is an explanatory diagram showing the configuration of the multi-value color laser printer, and FIG. 12 (a) , (b) is an explanatory diagram showing the configuration of the exposure system of the yellow recording unit, FIG. 13 is a block diagram showing multi-value drive using power modulation and pulse width/position modulation, and FIG. 14 is the configuration of the laser diode ON10FF circuit, etc. FIG. 15 is a circuit diagram showing a pulse width/position modulation circuit. FIGS. 16 to 28 are explanatory diagrams showing the operation of multi-level drive using power modulation and pulse width/position modulation. FIG. 29 is a circuit diagram showing a pulse width/position modulation circuit. (a), (b) are explanatory diagrams showing the effect of anti-aliasing processing, and Fig. 30 (a), (b), (C
) is an explanatory diagram showing an example of outputting a latent image based on conventional anti-aliasing processing. Explanation of symbols 100-host computer 110-11 laser writing section 111-laser diode 112-photoreceptor 200-
PDL controller 201-receiving device 202-CP U 2O5-internal system 20t-RAM 205--ROM 206-pacy memory 207-transmitting device 20 B-,
I10 device 300-image reading device 320-pulse width/position modulation circuit 321-D/A converter

Claims (2)

[Claims] (1) Anti-aliasing processing means that smoothly expresses jagged edges (aliases) of a vector image, and a pulse width modulation writing section and power modulation that outputs image data subjected to anti-aliasing processing by the anti-aliasing processing means. A graphic output device comprising: an image output means having a writing section; an end point determination means for determining an end point of the vector image; a vector number determination means for determining the number of vectors present in a pixel; Cross information detection means for detecting cross information in pixels; and selectively controlling the pulse width modulation writing section and the power modulation writing section based on the results of the end point determination means, the vector number determination means, and the cross information detection means. A graphic output device comprising a control means. (2) In claim 1, a first calculation means for calculating a pulse position from the coordinates of the end point; a storage means for storing pulse position information and pulse width information calculated by the first calculation means; A graphic output device characterized in that it comprises a second calculation means for calculating a more appropriate area ratio from each piece of information and the area ratio stored in the storage means.