JPH04144352A - Graphic output device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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. The present invention relates to a graphic output device that further enhances the effect of anti-aliasing processing on image data by controlling laser output from a multivalued color laser printer.

[Prior Art] FIG. 31 shows a driver in a conventional multilevel color laser printer using power modulation.

In multi-value drive by power modulation, since each of the plurality of drivers has the same configuration, here, the driver 505
y and the laser diode 504y will be explained as an example.

The driver 505y turns on/o the laser diode F504y based on a predetermined LD drive clock.
ff Laser diode on/off circuit 55
0, and a D/A converter 551 that converts 3-bit image density data (here, Y data) into an analog signal, and an analog signal based on the image density value is input from the D/A converter 551, and the laser diode 504y and a constant current circuit 552 that supplies a current (LD drive current) Td for driving the laser diode on/off circuit 550.

Here, the LD drive clock is defined as on at 1'' and off at 0, and the laser diode is on10f.
f circuit 550 accordingly connects laser diode 504
Turn off y. 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, a laser beam power output corresponding to the image density data value can be obtained. .

In the above configuration, the laser diode On/o
f f circuit 550 causes laser diode 504y
emits light, becomes a parallel light beam by a collimating lens 580, is shaped into a parallel light beam by an aperture 582, and is emitted to a polygon mirror 583.

As a result, in multilevel color laser printers that form an electrostatic latent image on a photoreceptor using the power modulation of image data that has undergone anti-aliasing processing, a pixel latent image as shown in Figure 32 is formed, and this figure is Compared to the image without aliasing processing (FIG. 34), it is clear that the jagged portions (aliases) on the steps that appear in the diagonal lines of the figure are visually smoothed out.

Incidentally, in a multilevel color laser printer that forms a latent image on a photoreceptor using pulse width modulation, a pixel latent image as shown in Figure 33 is formed, and this figure is converted into an image without anti-aliasing processing (see Figure 34). ), as in the case of power modulation described above, there is an effect of visually smoothing out the jagged portions (aliases) on the steps that appear in the hatched portions of the figure.

[Problem to be solved by the invention]

However, in multilevel color laser printers that form a latent image on a photoreceptor by power modulating image data that has undergone conventional anti-aliasing processing, the shape of the aperture is fixed, and the value of the current flowing through the laser diode or Since the multi-level write process was executed only by controlling the time during which the current was applied, the pixel latent image of the figure edge extending in the sub-scanning direction was separated from the upper and lower pixel latent images, as shown in FIG. However, there is a problem in that the effect of anti-aliasing processing, which visually smooths out jagged parts (aliases) on the steps, is diminished.

Similarly, as shown in FIG. 33, even in a multilevel color laser printer that forms a latent image on a photoreceptor by pulse width modulation, the pixel latent image of the figure edge extending in the main scanning direction is There is a problem in that the effect of anti-aliasing processing is diminished because it is separated from the pixel latent image.

Furthermore, in conventional multi-value color laser printers, multi-value writing processing is performed only by controlling the current value or the time period in which the current flows through the laser diode, as described above, so the effects of thermal dow loops can be avoided. However, there is also the problem that the image density fluctuates.

The present invention has been made in view of the above-mentioned problems, and the jagged portions (
The primary purpose is to enhance the visual smoothing effect of aliases).

A second purpose is to create a latent image with stable density without the influence of thermal dow loop.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an anti-aliasing processing means that smoothly expresses jagged edges (aliases) of an output image, and converts image data subjected to anti-aliasing processing into multivalued data using the anti-aliasing processing means. A graphic output device comprising an image output means for converting and outputting the image data, a shutter means arranged in an aperture section of the image output means and partitioned into a plurality of regions and capable of being opened and closed; The object of the present invention is to provide a graphic output device equipped with a control means for controlling the graphic output device.

Further, it is preferable that the shutter means is a liquid crystal shutter.

[Function] The graphic output device of the present invention is a multi-level color laser printer, in which an aperture equipped with a seven-trix shunter means is arranged, and the shutter means is controlled with the laser diode constantly lit. By this,
The shape of the laser beam can be changed arbitrarily in real time.

〔Example〕

Hereinafter, one embodiment of the graphic output device of the present invention will be described based on the drawings. ■ Schematic configuration of image forming system ■ Anti-aliasing processing ■ Configuration and operation of PDL controller ■ Configuration of image processing device ■ Multilevel color laser printer Configuration (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.

■Schematic configuration of image forming system The image forming system of this embodiment uses a page description language (Paper
ge Description Language
The configuration is such that image formation can be performed using image information of both hector data written in PDL language (hereinafter referred to as PDL language) and image information read by an image reading device.

The configuration of the image forming system of this embodiment will be described below with reference to FIG.

The image forming system uses a PDL command (in this embodiment, boss 1
A host computer 100 that creates a document written in the Hessflip 1-language) and a host computer 1
While applying anti-aliasing processing to the PDL language sent page by page from 00, red (R), green (G)
, PDL controller (anti-aliasing processing device of the present invention) 2 that develops images in three colors of blue (B)
00, an image reading device 300 that reads image information via an optical system unit, and a PDL controller 200, or an image that receives an image output from the image reading device 300 and performs image processing (details will be described later). A processing device 400, a multivalued color laser printer 500 that prints the multivalued image outputted by the image processing device 400, a PDL controller 200, an image reading device 300, an image processing bag w400, and a multivalued color laser. Printer 500 III? It is composed of a system control unit 600 for exporting data.

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

1. Uniform averaging method 111 Weighting is an averaging method iii, Convolution integral method Each of the above methods will be explained in turn.

, 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 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 hangs 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 maximum brightness of the gradation that can be displayed (for example, for 3 rounds on the 256th floor, kid
=255) is assigned. N=M for this pixel
When performing anti-aliasing processing using the uniform averaging method of =7, as shown in Figure (b), the pixels are
*Divides into 7 subpixels and counts the number of subpixels covered by the image. The maximum brightness (255) is obtained by dividing the count number (2 days) by the total number of subpixels in one pixel (49 in this case) and normalizing (averaging) it.
Multiply by 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 is applied to 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 determined depending on which subpixel the image covers. The effects are different. Note that the weight at this time is given using a filter.

With reference to FIGS. 3(a) and (b), FIG. 2(a),!
- An example is shown in which the same image data is weighted using the same dividing method (N=M=7) and the averaging method.

FIG. 3(a) shows a filter (here, cone f
itter ), 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. The same figure (b
) shows the display pattern of the image changed depending on the weight of the sub-pixels. In this case, if we ignore the weight and count the subpixels that are affected by the image, we get 199. This value is divided by the sum of the filter values (33G in this case) corresponding to the uniform averaging, averaged, and multiplied by the maximum brightness to calculate the brightness of this pixel. In addition, as a filter, Fig. 4 (a), (
Filters shown in b), (C), and (d) are known.

iii. Convolution integral method The convolution 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
' The intended pixel is indicated by 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 describes the content that makes up a single document, including the text (characters), graphics, etc.
Alternatively, it is a programming language for describing forms including their arrangement and appearance, and such systems employ vector fonts as character fonts. Therefore, even when characters are scaled, the print quality can be significantly improved compared to systems using Bittmann Pfsund (for example, conventional word processors), and character fonts and graphics can be It has the advantage that it is possible to print a mixture of images.

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), the number of filled sub-pixels 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.

iv. Method for obtaining approximate area ratio of edge pixels This anti-aliasing processing method calculates the presence or absence of intersections 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 6 (
With reference to a) to (f), 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.

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+y++yz is the intersection point X, as shown in FIG. 6(a). If it intersects at +XI+X2, this vector straight line L1
For example, the equation of these two points (Xo+yo)+(X
zy+) using the following equation (1).

3'+ V.

y 3'o −(x xo) −(1)x
, -X.

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
1. lz, I! 3. i! ,4. j23. fl
b, 17. Divide by 8 straight lines of 42□ (hereinafter referred to as dividing straight lines). Here, the equations of each straight line are expressed by the following equations (3) to 00).

Dividing straight line 1- +: x = O----(3)
lz: x = 1/3--- (4) 1!
3: X = 2 / 3 ---- (5) 14:
x = 1 ------- (6) (2s:
y = O---(force 12 b: y = 1
/ 3 ---- (8) 1, : y=2/3
--- (9) ρe: y = 1 ---
--00) Also, assuming that the equation of the hector straight line L1 obtained using the above equation (1) is y--(1/3)x+ (7/6)-(2), this vector straight line L1 and dividing straight lines fi,, f2, which divide the pixel P. ff 3. ! 1. i5p
,,p,,I! The coordinates of the intersections with , , and are shown in the following table.

Table Here, the range of χ and y゛ of pixel P in the χ° y゛ coordinate system is 0≦X゛≦1.0≦y''≦1, and therefore, an intersection exists within the range of this pixel P. The result is three dividing lines pV, 3.Ila, and Ee.Conversely, within the range of this pixel P, the three dividing lines j23.f
f14. The equation of a vector line that intersects only Nu is as shown in Figure 6 (C), where the intersection points are A and B, and the coordinates of intersection A are (1/3<x'≦2/3.y' −
1) The coordinates of intersection B are (x'=1.2/3<y'<1)
It will definitely pass through the range. Therefore, the three dividing straight lines 1s, Is, 1. The area ratios of pixels P that are divided by vector straight lines that intersect only with o are close to each other. The area ratio of the pixel 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 21, 2□, i3.14. fls,
! ! , b, lq, ff18 The individual area ratios of the set classified according to the intersection information can be approximated to one area ratio.

Therefore, in this anti-aliasing processing method, a set of straight lines is created based on 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. Then, for example, a LUT (Look Up Table) consisting of intersection information, edge information, and three approximate area ratios as shown in FIG. 6(d) 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 is -1 and the right edge flag is -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 straight line N,, fi2゜...
... indicates that lo and the vector straight line intersect (that is, there is an intersection). Figure (e) shows a straight line that can be considered under the conditions of data D of LUT.
The data D also includes information on the approximate area ratio of the shaded area shown in FIG. 3(e). Similarly, the same figure (f
), and the data D2 includes information on the approximate area ratio of the shaded area shown in FIG. Therefore, for example, when calculating the area ratio of the vector straight line shown in FIG.・・・・・・llll
Find the intersection with P D It, then determine whether the edge is a left edge or a right edge using the edge information determined by the P D It specifications, and based on these intersection information and edge information, calculate the corresponding approximate area from the LUT. Get the rate.

■Configuration and operation of PDL controller FIG. 7 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 a storage device for the PDL language received by the receiving device 201. A CPU 202 that performs control and anti-aliasing processing, and an internal system hash 20
3 and the receiving device 201 via the internal system HAS 203.
RAM 204 that stores the PDL language to be transferred from
RO that stores anti-aliasing programs, etc.
A page memory 20 that stores M2O3 and multivalued R, G, B image data subjected to anti-aliasing processing.
6, and a transmitting device 207 that transfers the RG and B image data stored in the page memory 206 to the image processing device 400.
and an I10 device 208 that performs transmission and reception with the system control unit 600.

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 path 203 according to the program stored in the ROM 205. After that, you will receive one page of PDL language,
Once stored in the RAM 204, the graphic elements in the RAM 2'04 are subjected to an anti-aliasing processing method based on the flowchart described later, and then stored in the plain memory section of the multilevel R, G, B image booter page memory 206 (page The memory 206 consists of a plain memory section of R, G, 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. 8(a) and 8(b).

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 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 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 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 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 process 3, while updating the X coordinate one by one,
Performs filling processing using scanning lines. For example, in Figure 8 (
When performing the bus filling process shown in b), the element on the side across which the scanning line yc to be processed and the real value of the X coordinate across the scanning line yc (X, x2 not shown in Figure 8(b)
χ, X4) and AET (Active Edge T
able: registered in a table that records the X coordinate of an edge portion appearing on a 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, 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, 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). Anti-aliasing processing is achieved in this filling processing by adjusting the density and brightness of the pixels in the edge portion according to the approximate area ratio. Then, remove the processed edge from the AET and update the scanline (X
coordinates) and repeats the same process until all edges in the AET are processed, in other words, until all elements in one path are processed.

” Biped process 1, process 2, and process 3 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. 8(C).

Here, for example, in process 1 of FIG. 8(a),
), this figure has the following elements.

(a) Five line vectors AB, BCXCD, DE, and EA (represented by real numbers) (b) Color and brightness values inside the figure As shown in Fig. 9(b), this figure is mainly It is divided into seven straight line vectors (expressed as real numbers) extending in the scanning direction. At this time, in this embodiment, the following information is added to the starting and ending points of the straight line vectors of the seven trees. That is, (c) Starting point coordinate value (real number expression) of the vector element ((a) above) that constitutes the starting point and ending point of the straight line vector (d) Slope information (*) of the vector element that constitutes the starting point and ending point of the straight line vector ) Characteristic information of the starting point and ending point of a straight line vector (right edge, left edge, apex of a figure, line of one dot or less, intersection of straight lines, etc.).

In the flowchart of FIG. 8(C), first, the starting pixel X of the anti-aliasing process, (x in FIG. 8(b)
1, pixels corresponding to χ3) are input (5401), and the equation of the straight line is calculated from the intersection with the filled scanning lines y and c (S402). The equation of this straight line and the dividing line N,
ffi□, j2:+, 1.4. ffs, lb,
E? , ρ. (S403), and based on the edge information (left edge, right edge, or vertex of the figure) in the feature information described above, 1. , UT and read the corresponding approximate area ratio (S404). after that,
The image data including the approximate area ratio is transferred to the line buffer (5405), and the image data is moved by one pixel in the X coordinate direction (540).
6) Determine whether the X-coordinate value of the pixel that has been moved by one pixel in the X-coordinate direction has reached the anti-aliasing processing completed pixel χe (pixel corresponding to X 2.X 4 in FIG. 2B); If it is not the end pixel XIl, return to 5403 and repeat the above process, and if it is the end pixel Xe, proceed to 3408 (
S407).

Subsequently, in 5408, it is determined whether all the pixels of the scanning line yc have been processed, and if the process is completed, the next image data is set, data shift: 5410), and the process 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 bumper 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. 9(a) obtained by the anti-aliasing process in this way has a value as shown in FIG. 10.

Here, if the figure in FIG. 9(a) has a white background color (
The figure color is red (maximum brightness: 25) on top of (maximum brightness: 255)
5), the approximate area ratio k (10th
(see figure), the brightness value for each color of the figure is (red),
(green) and Kb (blue) are obtained based on the following formula.

K, = KR,Xk 1KR2X(1-k)KG =
Kc+Xk+K6□×(1~k)Kb=KB
IXk 10KB2X (11'c) However, K R1-, K
G, , KBI indicate the brightness values of the figure colors (red, green, and blue, respectively) given in (II) above, and KR2,
KG2 and KIl□ indicate the luminance value of each previously painted color. Note that K, 2, Ko2, and KR2 refer to data in each plane memory section corresponding to R, G, and B of the page memory 206.

The brightness values of the brightness values Kr and KgK obtained in this way are as shown in FIGS. 11(a), (b), and (c).
R in the corresponding plain memory part of the page memory 206,
It is stored as C, B image data. For comparison, R, G, and B image data without anti-aliasing processing are shown in Figure 12 (a) and (b).
, shown in (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.
The three-color image signals read by D7r, 7g, and 7b are converted into blank (BK), yellow (Y), magenta (M), and cyan (C) recording signals necessary for recording. Similarly, the RGB image data given from the PDL controller 200 described above is converted into black (BK).
, yellow (Y), magenta (M), and cyan (C
) into each recording signal. Here, the image reading device 3
The mode for inputting image signals from 00 is copy machine mode, P
The mode in which RlG and B image data are input from the DL controller 200 is called a graphics mode.

The image processing device 400 includes CCDs 7r, 7g, and 7b.
111 color tone data obtained by A/D converting the output signal of
Shading correction circuit 401 that performs correction for sensitivity variations in internal terminal elements of CD7r, 7g, and 7b.
and a multiplexer 4 that selectively outputs either the color gradation data output from the shading correction circuit 401 or the color gradation data (R, G, B image data) output from the PDL controller 200 according to the above-described mode.
02, and a T correction circuit 403 that inputs the 8-bit data (color gradation data) output from the multiplexer 402, changes the gradation according to the characteristics of the light scattering object, and outputs it as 6-bit data. Output from 403 (R)
, 6-bit gradation data indicating the gradations of green (G) and blue (B) are used as their 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 and M output from the UCR processing/black generation circuit 407
.

Convert each 6-bit gradation data of C1 and BK to 3-bit gradation data Yl, Ml, CI, and BKI, and output to the laser drive processing section 502 inside the multi-color laser printer 500. The device consists of a gradation processing circuit 408 that synchronizes each circuit of the image processing device 400, and a synchronization control circuit 409 that synchronizes each circuit of the image processing device 400. Although the details are omitted, the γ correction circuit 403 can be operated from the operation button of the console 700. This configuration allows the gradation to be changed arbitrarily.

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, multivalued color laser printer 500
The number of gradations is the product of 3×3 area gradations and 3-bit (that is, 8 steps) multivalue level, and is 3×3×8=72 (8 floors).

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

Generally, the calculation formula for the masking process of the masking process circuit 406 is M.

C.

:Data before masking processing Y, , M, , Co: data after masking processing.

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 from these equations using the product of both coefficients.

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,.

Output values (such as yo'': values that are the calculation results of the UCR processing/black generation circuit 407) corresponding to Mi, C, (6 bits each) are obtained and stored in a predetermined memory in advance. Therefore,
In this embodiment, the masking processing circuit 406 and the UCR processing/black generation circuit 407 are composed of one set of ROM,
Data at the address specified by inputs Y, M, and C of the masking processing circuit 406 is given as an 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.
, and the C signal.A UCR processing/black generation circuit 407 performs correction for dark color balance in the superposition of toners of each color. UCR processing/black generation circuit 40
7, 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 γ correction circuit 403 executes processing based on the T correction conversion graph shown in FIG. 14, and the complementary color generation circuit 405 generates complementary colors shown in FIGS. Assuming that processing is executed based on the generation conversion graph, and then the masking processing circuit 406 and the UCR processing/black generation circuit 407 execute processing based on the following equations, FIGS. 11(a), (b), ( The R, G, B image data shown in C) is processed by the γ correction circuit 403. Complementary color generation circuit 405
．． After passing through the masking processing circuit 40B and the UCR processing/black generation circuit 407, the
C), converted as shown in (d).

Furthermore, if the gradation processing circuit 408 uses a Bayer type 3×3 multivalued dither matrix shown in FIG. 17, Y in FIGS. ,M
.

The data for C and BK are shown in Figure 18 (at (bL
(Converted to data shown in CL(d).

For comparison, when data without anti-aliasing processing (data in FIGS. 12(a), (b), and (C)) is processed by the image processing device 400, the data in FIGS. 19(a), ( b), (c), (a) Transform Salel as shown.

■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. Details will be given later, but BK Deday's development and
A black developing/transfer section 501bk that performs transfer, a cyan developing/transfer section 501c that develops and transfers C data,
Magenta development/transfer section 501 that performs M-pig development/transfer
m, 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 50 that outputs laser beams corresponding to Y, M, C, and BK, respectively.
4y.

504m, 504c 504bk and laser diode 504y, 504m, 504c.

Driver 505y505 that drives 504bk respectively
m, 505c, and 505b.

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. 21). 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 (see FIG. 21) and magenta developing/transfer section 501.
A combination of a laser diode 504m, a driver 505m, and a buffer memory 503m is connected to a magenta recording unit MU (see FIG. 21), a yellow developing/transfer section 501yl, and a laser diode 504.
y, driver 505 y, and.

The combination of buffer memories 503y is called a yellow recording unit YU (see FIG. 21). As shown in the figure, each of these recording units is connected to a transport heald 506 that transports the recording paper.
around the recording paper conveyance direction or rough-rank recording unit B.
They are arranged in this order: KU, cyan recording unit CU, magenta recording units 1 to MU, and yellow recording unit YU.

With this arrangement of the recording units 1 to 1, the laser diode 504bk for black exposure starts exposure first, 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, 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 includes the three sets of buffer memories 503y, 503m, and 503C described above.
is provided.

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

The multilevel color laser printer 500 includes a conveyor belt 506 that conveys recording paper, and recording units YU, MU, and YU arranged around the conveyor belt 506 as described above.
Paper cassette 507 containing CU, BKU, and recording paper
a, 507b, and paper feed rollers 508a, 508b that feed the recording paper from paper feed rollers 507a, 507b, respectively.
The recording units I-BKU, CU, and the registration rollers 509 that align the recording sheets sent out from the paper feed cassettes 507a and 507b, and the conveyance heald 506,
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 photosensitive drums 512y, 512m, 512c, 51
2bk, and photoreceptor drums 512y and 512m, respectively.

Charger 513y that uniformly charges 512c and 512bk
, 513m, 513c, 513bk, and photosensitive drum 5
12y, 512m, 512c.

Polygon mirrors 514y, 514m, 514c514bk and motors 515y, 515m515c, 515bk for guiding laser beams to 512bk and electrostatic latent images formed on photoreceptor drums 512y512m, 512c, 512bk are formed using toners of respective colors. Toner developing devices 516y and 516m perform development.

516c, 5L6bk, and transfer charger 517y, 517m517c 5, which transfers the developed toner image to recording paper.
] 7bk, and the photosensitive drum 512y after transfer, 5
12m, 512c, 512bkl cleaning device 518y, 51 for removing toner remaining on
It consists of 8m, 518c, and 518bk. In addition, 5
19y, 519m, 519c, and 519bk are photoconductor trams 512y, 512m, and 512c, respectively.
, 512bkl for reading a predetermined pattern. Although the details are omitted, the process status of the multi-value color laser printer 500 is detected by this COD line sensor.

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

Figures 22(a) and (b) show yellow recording unit YU.
The configuration of the exposure system is shown. 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 a mirror 521y522y, and is irradiated onto a photoreceptor drum 512y through a dustproof glass 523y. be done. 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 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 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
As shown in FIG. 21, the paper is fed out from the cassette 507a (or 507b) by the U feed roller 508a (or 508b), and is conveyed by the registration roller 509 in synchronization with the toner image formation in the black recording unit BKU. hell l-5
The image is transferred onto the recording paper conveyed by 06.

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 blank toner developing device 516bk and forms and transfers a black toner image, and the cyan recording unit C
U is equipped with a cyan toner developing device 516C and a cyan toner developing device 516C.
Forms and transfers henna images, magenta recording unit M
U includes a magenta toner developing device 516m, which forms and transfers a magenta toner image.

■The multi-value drive drivers 505y, 505m, 505c505bk are
Y, M, C, BK sent from the image processing device 400
Based on the 3-bit data of ing.

Hereinafter, multi-value drive by power modulation applied in this embodiment will be explained in detail with reference to FIGS. 23 to 28. Furthermore, the drivers 505y and 505m.

505c, 505bk, and laser diode 50
4y, 504m, 504c, and 504bk each have the same configuration, so here, the driver 505y and laser diode 504y will be explained as an example.

As shown in FIG. 23(a), the driver 505y turns the laser diode 504y on and off based on a predetermined LD drive clock.
An n/o f f circuit 550, a D/A converter 551 that converts 3-bit image density data (here, Y data) into an analog signal, and an analog signal based on the image density value input from the D/A converter 551. Then, the current (LD drive current) Id for driving the laser diode 504y is set to the laser diode 0n10ff circuit 550.
The constant current circuit 552 supplies the current to the constant current circuit 552.

In the above configuration, the laser diode 0n10ff
The circuit 550 causes the laser diode 504y to emit light, the collimating lens 580 converts the light into a parallel light beam, the aperture 582 adjusts the shape of the light beam, and the light beam is emitted to the polygon mirror 583.

The aperture 582 is provided with a liquid crystal shutter and changes the shape of the aperture.

FIG. 23(b) shows an example in which the aperture 582 is divided into three parts using the liquid crystal shutter.

That is, the aperture 582 is divided into three windows, each of which is composed of a liquid crystal shutter, and is controlled by the aperture control circuit 581 so that any window can be opened and closed at high speed in synchronization with the write clock.

In this case, the size of the beam is set to be vertical when all the windows are open. If all the windows are closed, no laser light will be emitted, so the laser diode 5
04y may be left lit all the time.

The opening/closing control of the aperture 582 by the liquid crystal shutter described above is explained based on power modulation processing, but it can also be applied to pulse width modulation processing.

As a result, control using the following combinations becomes possible.

■Power modulation processor with shutter means control Pulse width modulation processing ■Pulse width modulation processor with shutter means control Power modulation processing ■Power modulation processing with shutter means control 10 Pulse width modulation processing with shutter means control Combinations of the above This further increases the effectiveness of anti-aliasing processing.

FIG. 24 shows a schematic configuration of the aperture control circuit 581 shown in FIG. 23(a).

Assume that the result of one dot in the subpixel filling processing unit 590 during antialiasing processing is as shown in FIG. 25 (here, the number of subpixels is 1 dot 3 ×
3). This one-dot sub-pixel is stored in the RAM 59 as data of three bits at the top, middle, and bottom, and three words in the main scanning direction.
Store in 1. The bedtime of the above one dot was divided into three equal parts, TI, T2. Let it be T3.

The RAM control device 592 stores three words of data in the main scanning direction as TI, T2, . Output at time T3.

The liquid crystal shutter of the aperture 582 is the RAM 59
Based on the signal from 1, the liquid crystal shutter drive device 593 opens and closes the shutter at high speed, and changes the state at each time shown below.

■At T1, all the liquid crystal shutters are closed because none of the subpixels are filled.

■At T2, the lower subpixel is filled in, so open the lower liquid crystal shutter.

■At T3, the upper, middle, and lower sub-pixels are filled in, so open the upper, middle, and lower liquid crystal shutters.

The above operations are performed sequentially for all dots.

When such an operation is performed, a latent image having the same shape as the sub-pixel can be formed.

Here, the LD drive black is turned on with “I” and “0”.
”, and as shown in FIG. 26, the laser diode on/off circuit 550 turns the laser diode 504y on and off accordingly.
f. Also, since the LD drive current Id and the laser beam power are in a proportional relationship, based on the image density data value
By generating the D drive current 1d, a laser beam power output corresponding to the image density data value can be obtained. For example, as shown in FIG. 26, when the image density data value is "4" (data N-1 in the figure), the constant current circuit 552 supplies the corresponding LD drive current Id, and the laser diode 504y The laser beam power will be level 4. Also, if 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, referring to FIG. 27, the laser diode on
/ o (f circuit 550. D/A converter 551
Also, a specific circuit configuration of the constant current circuit 552 will be explained.

The laser diode on10ff circuit 550 is TTL
Inverters 553 and 554, differential switching circuits 555 and 556 that perform 0n10ff toggle operation, and V
When GI>VO2, the differential switching circuit 555
n, differential switching circuit 556 is off, VGI<
When VO2, the differential switching circuit 555 is off,
Resistors R2 and R form a voltage dividing circuit that generates VO2 that satisfies the conditions for the differential switching circuit 556 to be turned on.
It consists of 3. Therefore, when the ID drive clock is 1, the output of the in-harc 554 generates VGI, the above condition (VGI>VO2) is satisfied, and the differential switching circuit 555 is turned on.

The differential switching circuit 556 is turned off and the laser diode 504y is turned on. Conversely, when the LD drive clock is at 0°, there is no output from the inverter 554, so the above condition (VGI<VO2) is satisfied, the differential switching circuit 555 is off, and the differential switching circuit 556 is off. Turn on the laser diode 504
Turn off y.

The D/A converter 551 has a latch 5 that latches the input image density data while the LD drive clock is 1°.
57, and V r a f giving the maximum output value V ref
Generator 558, image density data and maximum output value V r
A 3-bit D/A converter 559 outputs analog data Vd based on sf. Note that the relationship between Vd, image density data, and maximum output value V rllf 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 R, , R9. The output V,d 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 ld flowing through the laser diode 504y is controlled by Vd.

FIG. 28 shows the output VGI V of the latch 557 mentioned above.
d is a timing chart showing the relationship between Id and Id. Here, Vd is image density data (3-bit data: 0
Vrar x O/
Values are taken in eight stages from 7 to 7/7, and Id indicates eight levels from ■ to ■7 based on the value of Vd. The laser diode 504y has 8 levels of this Id (
1,-level 0. It-Rehert..., (7-Reher 7), a latent image as shown in FIG. 29 is formed on the photosensitive drum 512y.

Further, in this embodiment, multivalue drive using power modulation is applied, but it goes without saying that the same effect can be obtained by using multivalue drive using pulse width modulation.

For reference, changes in the latent image form depending on the level of pulse width modulation are not shown in FIG. 30G.

According to the present invention, not only the number of gradations can be increased, but also a dot latent image of any shape can be created. In particular, since it is possible to create a latent image of dots with vertically biased shapes, which was impossible with conventional power modulation processing, it is possible to further enhance the effect of anti-aliasing processing.

Furthermore, since the laser diode can be kept on at all times, it is possible to create a latent image with stable density without the influence of thermal dow loop.

〔Effect of the invention〕

As explained above, according to the graphic processing apparatus according to the present invention, an anti-aliasing processing means for smoothly expressing jagged edges (aliasing) of an output image, and an image subjected to anti-aliasing processing by the anti-aliasing processing means A graphic output device comprising an image output means for converting data into multi-valued data and outputting the same, comprising: a shack means arranged in an aperture section of the image output means and partitioned into a plurality of areas, which can be opened and closed; and the shutter means. Since the present invention is provided with a control means for controlling the image data according to the image data, it is possible to enhance the effect of visually smoothing out jagged portions (aliases) on the steps caused by anti-aliasing processing of graphics.

Further, it is possible to create a latent image with stable density without the influence of thermal dow loop.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of the image forming system of this embodiment, FIGS. 2(a) and [b] are explanatory diagrams showing anti-aliasing processing using the uniform averaging method, and FIGS.
(b) is an explanatory diagram showing anti-aliasing processing using weighted averaging method, Figure 4 (a), (b), (C)
, (cl) is an explanatory diagram showing an example of a filter used in the weighted averaging method, Fig. 5 is an explanatory diagram showing a convolution method with 3 x 3 pixel reference, Figs. 6 (a), (b), (
C), (d). (e) and (f) are explanatory diagrams showing antialiasing processing to obtain the approximate area ratio of edge pixels, and FIG.
An explanatory diagram showing the configuration of the L controller, FIG. 8(a) is the P
A flowchart showing the operation of the DL controller, FIG. 8(b) is an explanatory diagram showing the path filling process, FIG.
C) is a flowchart showing the anti-aliasing process of the present invention, FIGS. 9(a) and (b) are explanatory diagrams showing linear vector division of a figure, and FIG. 10 is the area ratio near 1 or more after performing the anti-aliasing process. An explanatory diagram showing Fig. 11 (
a), (b), and (C) are explanatory diagrams showing R, G, and B image data stored in the plain memory section of the page memory, and Fig. 12 (a), (b), and (C) are anti-aliasing diagrams. An explanatory diagram showing the RG and B image data stored in the brain memory section of the page memory when no processing is performed, FIG. 13 is an explanatory diagram showing the configuration of the image processing device, and FIG. 14 is the γ of the T correction circuit. An explanatory diagram showing a conversion graph for correction, Fig. 15 (a), (b), (C) is an explanatory diagram showing a conversion graph for complementary color generation used in a complementary color generation circuit, Fig. 16 (a), (b) . (C), (d) are shown in Figure 11 (a), (b), (C
) is an explanatory diagram showing the state in which the R, G, B image data shown in FIG. 17 is output from the UCR processing/black generation circuit. Figure 18 (a), (b), (C), and (d) are Y, M, and C in Figure 16 (a), (b), (C), and (d).
, BK data converted by the gradation processing circuit, FIGS. 19(a)(b), (C1,(d)
FIG. 12 is an explanatory diagram showing the state in which the data in (a), (b), and (C) are processed by the image processing device; FIG. 20 is a control block diagram showing a multivalued color laser printer; and FIG. An explanatory diagram showing the configuration of a multi-value color laser printer, FIGS. 22(a) and 22(b) are explanatory diagrams showing the configuration of the exposure system of the yellow recording unit, and FIG. 23(a) shows multi-value driving using power modulation. An explanatory diagram showing Fig. 23 (b
) is an explanatory diagram showing the configuration of the liquid crystal shunter, FIG. 24 is a block diagram showing the configuration of the aperture control circuit, FIG. 25 is an example of the result of one tonto in the sub-pixel fill processing section, and FIGS. 26 and 28. 27 is a circuit diagram showing the configuration of the laser diode ON10ff circuit, etc., FIG. 29 is an explanatory diagram showing the state of the latent image depending on the power modulation level, and FIG. 30 is a timing chart explaining the operation of the laser diode. 31 is an explanatory diagram showing the state of a latent image depending on the level of pulse width modulation, FIG. 31 is an explanatory diagram showing multi-level driving using conventional power modulation, and FIG. 32 is an explanatory diagram showing the state of the latent image depending on the level of pulse width modulation. 33 is an explanatory diagram showing a toner image when power modulation is applied to ABCDE. FIG. 33 is an explanatory diagram showing a toner image when pulse width modulation is applied to the conventional pentagonal ABCDE shown in FIG. 9(a). FIG. 34 is an explanatory diagram showing a toner image when anti-aliasing processing is not performed. Description of symbols 100--Host computer 200-PD L controller 201-Receiving device 202-CPU 2O5--Internal system 20, L-RAM 205-ROM 206-Pacific memory 207-Transmitting device 20 B-1
70 Device 30 (1-Image reading device Image processing device Multi-level color laser printer Collimating lens Aperture control circuit 582 Aperture polygon mirror sub-pixel filling processing section RAM 592-RAM control device Liquid crystal shutter drive circuit System control section

Claims (2)

[Claims] (1) Anti-aliasing processing means for smoothly expressing jagged edges (aliases) in the output image; and image output means for converting the anti-aliased image data into multivalued data by the anti-aliasing processing means and outputting the multi-valued image data. A graphic output device comprising: a shutter means disposed in an aperture portion of the image output means and partitioned into a plurality of regions that can be opened and closed; and a control means controlling the shutter means according to the image data. A graphic output device characterized by: (2) The graphic output device according to claim 1, wherein the shutter means is a liquid crystal shutter.