JP3148291B2 - Graphic output device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic output apparatus for performing an anti-aliasing process for removing jaggies at edges of an output image. In the modulation process of
The present invention relates to a graphic output device that continuously modulates the power of a laser beam.

[0002]

2. Description of the Related Art In the field of computer graphics, when an image is displayed on a CRT as an output medium, a method called an anti-aliasing process is used to make the displayed image more beautiful.

In this processing, a jagged portion (referred to as an alias) on a stair as shown in FIG. 52A is subjected to luminance modulation to visually smooth a displayed image as shown in FIG. 52B. Things.

As a method of outputting data after the anti-aliasing processing, there is a multi-valued color laser printer. As a driving method, a power modulation method and a pulse width modulation method are generally used.

[0005] Japanese Patent Laid-Open No. HEI 9-107556 discloses an apparatus for inputting image data of a bit pattern image, recognizing the binary image data in small areas, performing pattern recognition, and performing correction (anti-aliasing processing) to improve the display. 2-11
No. 2,966.

[0006]

However, conventionally,
Since the gradation can be intermittently obtained only in n stages, even if anti-aliasing is performed on each pixel, the modulation result changes stepwise over several pixels in the graphic output stage. There was a point.

Further, according to the conventional anti-aliasing method and apparatus, one pixel is divided into a plurality of sub-pixels (for example, 49 sub-pixels), and the number of sub-pixels to be filled is counted. Since the area ratio (luminance) is calculated, it takes time to calculate the area ratio, which hinders an improvement in display speed or printing speed. In particular, the convolution integration method has a problem that it is difficult to improve the processing speed because the calculation amount is large and a plurality of pixels are affected.

Further, Japanese Patent Publication No. 2-112966 also has a problem that the continuity of the image is lost and the effect of the anti-aliasing processing is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made in consideration of the above. It is possible to ensure the continuity of an image, reduce the number of pixels for performing anti-aliasing processing, and perform anti-aliasing processing at high speed and efficiently. It is a first object to obtain a processed image.

Further, the present invention has been made in view of the above, and secures continuity of an image, and does not execute area ratio calculation in anti-aliasing processing.
A second object is to obtain an image subjected to anti-aliasing processing at high speed and efficiently.

The present invention has been made in view of the above, and it is a third object of the present invention to ensure the continuity of an image and to output image data of a bit pattern image with high quality.

[0012]

According to the present invention, there is provided a graphic output apparatus for performing an anti-aliasing process for smoothly expressing a jagged (alias) at an edge portion of a vector image. Image output means for outputting image data by continuously changing laser beam power; position determination means for determining an adjustment start position and an adjustment end position (edge position) of the beam power; and an edge on a scan line. A pixel detecting means for detecting a pixel farthest from the image portion among several pixels covered by, a density detecting means for obtaining a pixel density detected by the pixel detecting means in the anti-aliasing process, The laser beam from the pixel detected by the detection means to the image portion; There is provided a graphics output device and a control means for changing toward the word continuously maximum.

According to another aspect of the present invention, there is provided a graphic output apparatus for performing an anti-aliasing process for smoothly expressing jaggies (alias) at an edge portion of a vector image. Image output means for continuously changing and outputting the beam power, and an adjustment start position of the beam power,
Position determining means for determining an adjustment end position (edge position); pixel detecting means for detecting a pixel farthest from an image portion among several pixels with edges on a scan line; Density detecting means for determining the pixel density detected by the means in the anti-aliasing processing; determining means for determining whether the edge to be processed is a right edge or a left edge; When it is determined that the edge is an edge, the pixel density is used as the power at the end of power modulation, and a power modulation process is performed using the image output unit. Control means for executing power modulation processing using the image output means as the power at the start of modulation. There is provided a Bei the graphics output device.

Further, since the present invention is to achieve the second purpose, the graphics output device for performing an anti-aliasing process to smoothly represent jagged edges of the vector image (alias), the vector image data Image output means for continuously changing and outputting the laser beam power, and an adjustment start position of the beam power,
Position determining means for determining an adjustment end position (edge position) in a unit smaller than a pixel unit; determining means for determining whether the processing target edge is a right edge or a left edge; When the means determines that the right edge, from the adjustment start position to the adjustment end position,
Using the image output means, change the power from the minimum value to the maximum value, conversely, when the determination means determines the left edge, from the adjustment start position to the adjustment end position, using the image output means, And a control unit for changing the power from a maximum value to a minimum value.

Further, since the present invention is to achieve the second purpose, the anti-aliasing process means to smoothly represent jagged edges of the vector image (alias), by the anti-aliasing process means, antialiasing Image output means for outputting the image data by continuously changing the laser beam power,
Density detection means for detecting a pixel density immediately before and immediately after an edge portion of the vector image; position determination means for determining an adjustment start position of the beam power and an adjustment end position (edge position) in a unit smaller than a pixel unit; Control means for continuously changing the beam power of the image output means from the beam power adjustment range obtained by the position determination means to the density immediately before the edge portion detected by the density detection means to the density immediately after the edge portion. A graphic output device is provided.

Furthermore, the present invention is to achieve the third purpose, the image data bit pattern image, against a predetermined pattern stored in advance to the bit map generates a compensation data Then, in a graphic output device for improving the image quality of the output image by combining and outputting the image data and the compensation data, based on the compensation data, the laser beam power of the portion to be compensated for the image data , For dots smaller than the specified dot diameter
Is to submit a graphics output device provided with the beam power modulation processing means for outputting continuously modulated so that the laser beam. In this case, it is preferable that the compensation data include information on a modulation start position or information on a modulation stop position of the laser beam and information indicating up to which pixel the beam power is to be modulated.

[0017]

According to the graphic output device of the present invention, when outputting an anti-aliasing processing result in a laser beam printer, only the density of the pixel at the end of each edge is determined. The modulation from the pixel to the image portion is obtained by an anti-aliasing process, and is executed by continuously changing the beam power toward the maximum value. As a result, it is possible to prevent the modulation result from changing stepwise over several pixels because the gradation is intermittently obtained in n steps.

A graphic output device according to the present invention, when outputting an anti-aliasing result in a laser beam printer, uses a beam power from an endmost pixel (pixel) to an image portion at each edge. The modulation is continuously performed from the minimum value to the maximum value. that time,
The start position and the end position of the beam power change are controlled with a width smaller than one pixel (1 / (n-1) pixel width in the case of n-stage density expression).

According to a fourth aspect of the present invention, in the laser beam printer, the laser beam printer performs anti-aliasing processing by continuously modulating the power of the beam from the end pixel (pixel) to the image portion at each edge. Run by letting it do. The modulation range of the beam power is determined by the pixel densities immediately before and after several pixels on the scan line with edges. Further, the start position and the end position of the beam power change are controlled with a width smaller than one pixel (1 / (n-1) pixel width in the case of n-stage density expression).

The graphic output device (claim 5 and claim 6) of the present invention, when outputting a bit pattern image,
The laser beam power of a portion to be compensated for image data is continuously adjusted based on compensation data consisting of laser beam modulation start position information or modulation stop position information and information indicating up to which pixel the beam power is to be modulated. And output the image.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a graphic output device according to the present invention will be described in detail in the order of [Embodiment 1], [Embodiment 2], [Embodiment 3], [Embodiment 4] with reference to the drawings.

[First Embodiment] First, the schematic configuration of an image forming system, an anti-aliasing process, the configuration and operation of a PDL controller, the configuration of an image processing device, and the The configuration of the color laser printer (the configuration and operation of the developing unit of the multi-level color laser printer), the multi-level driving of the driver, and a specific operation example will be described in detail in this order.

The image forming the image forming system of a schematic configuration example 1 of the system, DTP (desk top publishing) page description language that is output from the (Page Description Language: hereinafter referred to as PDL language) described by In this configuration, image information of both vector data and image information read by the image reading device can be formed.

The configuration of the image forming system according to the first embodiment will be described below with reference to FIG. The image forming system is P
DL language (postscript language is used in this embodiment)
Computer 100 that creates a document described in
And a PDL controller 200 for developing the PDL language sent from the host computer 100 in page units into three color image images of red (R), green (G), and blue (B) while performing anti-aliasing processing. Reading device 30 for reading image information via optical system unit
0, an image processing device 400 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),
A multi-level color laser printer 500 for printing multi-level image data output from the image processing apparatus 400, and a PD
It comprises an L controller 200, an image reading device 300, an image processing device 400, and a system control unit 600 for controlling the multi-value color laser printer 500.

Anti-aliasing processing The following method is known as an anti-aliasing processing method. i. Uniform averaging method ii. Weighted averaging method iii. Convolution Integral Method Each of the above methods will be described in order.

I. Uniform Averaging Method In the uniform averaging method, each pixel (pixel) is represented by N * M (N, M
Is a natural number), is subjected to raster calculation at high resolution, and then the luminance of each pixel is obtained by averaging N * M sub-pixels. FIG. 2 (a),
The anti-aliasing processing by the uniform averaging method will be specifically described with reference to FIG.

When an edge of the image is applied to a certain pixel (here, the image is connected to the lower right of the diagonal line), and when the anti-aliasing processing is not performed, FIG. So the brightness kid of this pixel
Is assigned the highest luminance of displayable gradations (for example, kid = 255 for 256 gradations). N for this pixel
When the anti-aliasing process by the uniform averaging method of = M = 7 is performed, the pixels are decomposed into 7 * 7 sub-pixels and the number of sub-pixels covered by the image is reduced as shown in FIG. Count. The count number (2
8) is the total number of subpixels in one pixel (in this case, 4
9) and standardized (averaged) to obtain the maximum luminance (2
55) to calculate the luminance of the pixel. As described above, in the uniform averaging method, the brightness of each pixel is determined in consideration of how the image is applied to each pixel.

Ii. Weighted Averaging Method The weighted averaging method is a partial modification of the uniform averaging method. In the uniform averaging method, all the subpixels in one pixel have the same weight (that is, the subpixels on which the image is applied are simply weighted) In contrast, the weighted averaging method weights each sub-pixel so that the effect on the luminance kid of that sub-pixel depends on which sub-pixel the image covers. . The weight at this time is given using a filter.

Referring to FIGS. 3A and 3B, FIG.
The same division method (N = M = 7) for the same image data as in (a)
Shows an example in which the weighted averaging method is performed. FIG. 3 (a)
Indicates the characteristics of the filter (here, a conefilter), and the corresponding sub-pixels are given the same weight as the characteristics. For example, the weight of the sub-pixel at the upper right corner is 2. When an image is applied to each sub-pixel, the value of the weight given by the filter characteristic becomes the count value of the sub-pixel. FIG. 7B shows a different display pattern of the image depending on the difference in the weight of the sub-pixel. In this case, when the weighted sub-pixels of the image are counted, the number is 199. This value is averaged by dividing by the sum of the filter values (336 in this case) corresponding to the uniform averaging, and multiplying by the highest luminance to calculate the luminance of this pixel. Note that the filters shown in FIGS. 4A, 4B, 4C, and 4D are known as filters.

Iii. Convolution Integral Method The convolution integral method is a method of determining the luminance of one pixel by referring to the surrounding pixels. That is, it is considered that N ′ × N ′ pixels around one pixel whose luminance is to be determined correspond to pixels of the uniform averaging method or the weighted averaging method. Figure 5 is 3x
3 illustrates a convolution method with three pixels. In this figure, the pixel whose luminance is to be determined is indicated by 51. The image continues to the lower right of the diagonal line, and the subpixels painted black are the subpixels to be counted. Each pixel is divided into 4 * 4. Therefore, in this case, a 12 * 12 filter is used. This method has the effect of removing high frequency components contained in the vector image.

On the other hand, with the spread of a publishing system using a personal computer, so-called DTP (desktop publishing), a system for printing vector images handled by computer graphics has been widely used. . A typical example is a system using Adobe Post Script. Post script belongs to the language genre of the page description language, and includes a text (character portion), graphics, or a form including the arrangement and appearance of the contents constituting one document. This system uses a vector font as a character font. Therefore, even if you scale the characters,
Compared to a system using a bitmap font (for example, a conventional word processor), the printing quality can be remarkably improved, and the character font, graphic and image can be mixed and printed. is there.

However, according to the conventional anti-aliasing method and apparatus, one pixel is divided into a plurality of sub-pixels (for example, 49 sub-pixels), and the number of sub-pixels to be filled is counted. Since the area ratio (luminance) is calculated, it takes time to calculate the area ratio, which hinders an improvement in display speed or printing speed. In particular, the convolution method is
There is a problem that it is difficult to improve the processing speed because a large amount of calculation affects a plurality of pixels. In view of the above, there has been proposed an anti-aliasing technique for obtaining an area ratio at high speed without performing sub-pixel division and counting of the number of painted areas.

Iv. Method of Obtaining Approximate Area Ratio of Edge Pixels This anti-aliasing processing method is based on the presence or absence of an intersection between vector data and a predetermined straight line group when the edge pixels are divided by a predetermined straight line group, and the type of edge. Thus, an approximate area ratio of the edge portion pixel is obtained. Hereinafter, a method of obtaining the approximate area ratio from the presence or absence of the intersection and the type of the edge will be described in detail with reference to FIGS.

A straight line L given by vector data
1 (hereinafter referred to as a vector straight line L1) and the sub-scanning direction y
When the respective lines y ₀ , y ₁ , and y ₂ intersect at intersections x ₀ , x ₁ , and x ₂ as shown in FIG. 6A, the equation of this vector line L1 is, for example, (X ₀ , y
₀ ) and (x ₁ , y ₁ ) can be obtained by Expression (1) shown in Expression 1.

[0035]

(Equation 1)

On the other hand, focusing on the pixel P, a new x'y '
Set the coordinate system, as shown in FIG. 6 (b), a straight line l ₁ of the pixel _{P, l 2, l 3,} l 4, l 5, l 6, l 7, l 8
(Hereinafter, referred to as division straight lines). Here, the equation of each straight line is given by the equation (3) shown in Equation 2.
To (10).

[0037]

(Equation 2)

Assuming that the equation of the vector straight line L1 obtained by the above equation (1) is the equation (2) shown in the following equation (3).

(Equation 3) The vector straight line L1 and the divided linear l ₁ to divide the pixel _{P, l 2, l 3,} l 4, l 5, l 6, l 7, each intersection coordinates between l ₈ which is shown in the table below.

[0039]

[Table 1]

Here, the range of x ′ and y ′ of the pixel P in the x′y ′ coordinate system is 0 ≦ x ′ ≦ 1, 0 ≦ y ′ ≦ 1, and therefore, within the range of this pixel P Intersections exist at three divided straight lines, namely, divided straight lines l3, l4, and l8. Conversely, within the range of the pixel P, the three divided straight lines l
The equation of a vector straight line having intersections with only 3, l4 and l8 is as follows. If the intersections are A and B as shown in FIG. 7A, the coordinates of the intersection A are (1/3 <x'≤2 / 3). , Y '=
1), the coordinates of the intersection B is particularly must pass through the range of (x '= 1, 2/3 <y'<1). Therefore, the area ratio of the pixel P divided by the vector straight line having the intersection with only the three divided straight lines l3, l4, and l8 shows close values, in other words, the pixel P has the intersection with the predetermined divided straight line group. When the vector line group is one set, the area ratio of the pixels P divided by the vector line group of the set indicates a similar area ratio in a predetermined range. Therefore, the vector line and the division lines l1, l2, l3, l4, l5, l6, l7,.
Each area ratio of the set classified by the intersection information with l8 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 the edge information indicating the left or right edge, and the approximate area ratio is determined in advance for each set. Then, for example, as shown in FIG. 7B, intersection information, edge information, and
Create an LUT (LookUpTable) consisting of approximate area ratios. After that, when performing anti-aliasing processing, instead of performing sub-pixel division to calculate the area ratio of the edge part pixel, the corresponding approximate area ratio is input from the LUT based on the intersection information and the edge part information. Thus, the output of the edge portion pixel is adjusted.

In the LUT shown in FIG. 7B, the edge information flag indicates the left edge when the left edge flag = 1 and the right edge flag = 0, and indicates the left edge flag when the left edge flag = 0 and the right edge flag = 1. Sometimes shows the right edge. When the left edge flag = the right edge flag = 1, FIG.
And when the dividing straight line flag = 1,
This indicates that each of the division straight lines l ₁ , l ₂ , ‥‥‥ l ₈ intersects with the vector line (that is, there is an intersection). FIG. 3C shows a straight line that can be considered under the condition of the LUT data D ₁ , and the data D _{1 also} has, as information, an approximate area ratio of a hatched portion shown in FIG. Similarly, FIG. 6D shows a straight line that can be considered under the condition of the LUT data D ₂ , and the data D ₂ has the approximate area ratio of the hatched portion shown in FIG. Therefore, for example, when calculating the area ratio of the vector straight line in FIG. 9C, the vector straight line and the divided straight lines l ₁ and l
₂ , ‥‥‥ l _8, and then determine whether the edge is a left edge or a right edge by using edge information determined by the PDL specification. Based on the intersection information and the edge information, the LUT To obtain the corresponding approximate area ratio.

FIG. 8 shows the configuration of the PDL controller 200. FIG. 8 shows a receiving apparatus 201 for receiving the PDL language sent from the host computer 100, and a PDL received by the receiving apparatus 201.
A CPU 202 for controlling the storage of the DL language and executing an anti-aliasing process, an internal system bus 203,
A RAM 204 for storing a PDL language to be transferred from the receiving device 201 via the internal system bus 203, and a ROM 205 for storing an anti-aliasing program and the like
A page memory 206 for storing multi-valued RGB image data subjected to anti-aliasing processing, a transmitting device 207 for transferring the RGB image data stored in the page memory 206 to the image processing device 400, and a system control unit 600. And an I / O device 208 that performs transmission and reception.

Here, the CPU 202 includes the receiving device 201
Through the internal system bus 203 according to the program stored in the ROM 205.
Store it in the AM 204. Thereafter, when the PDL language for one page is received and stored in the RAM 204, the RAM 204
Apply anti-aliasing processing method to the graphic elements in the
The multi-valued RGB image data is stored in the plane memory of the page memory 206. The page memory 206
Is a plane memory unit 2 of R, G, B as shown in FIG.
06a and a characteristic information memory unit 206b. The data in the page memory 206 is then transmitted to the transmission device 207
Is sent to the image processing apparatus 400 via the.

Hereinafter, the operation of the PDL controller 200 will be described with reference to FIG. FIG. 10A shows the CPU.
2 shows a flowchart of a process performed by the CPU 202. The PDL controller 200 performs the anti-aliasing process on the PDL language sent from the host computer 100 in page units as described above, and performs three color image images of red (R), green (G), and blue (B). Expand to

In the PDL language, both graphics and characters are described in vector data, and as indicated by the term “page description language”, the processing unit of image information is handled in page units. Further, one page is composed of at least one path in units of a path composed of one or a plurality of elements (graphic elements and character elements).

First, when the PDL language is input, it is determined whether or not the element is a curve vector. If the element is a curve vector, this is approximated to a straight line vector and registered in the work area as a straight line element (line). This is performed for all figures and character elements in one pass, and the registration of linear elements in the work area is performed for each pass (Process 1).

Then, the straight line elements of the work area registered for each pass are sorted by the starting y-coordinate of the straight line (process 2).

Next, in process 3, while updating the y-coordinates one by one, a filling process using scanning lines is performed. For example, when the path filling process shown in FIG. 10B is performed, the elements on the sides crossing the scanning line yc to be processed and the real numerical values of the x coordinate crossing the scanning line yc (shown in FIG. 10B) _{x 1, x 2, x 3} , x 4) and AET (Active Edg
e Table: Register in the table that records the x-coordinate of the edge that appears on the scanning line.

Here, since the order of the elements registered in the work area is the order registered in the processing 1, the elements are not always registered in the order of smaller x-coordinates crossing the scanning line yc. For example, in process 1, FIG.
Linear element passing through the scanning line yc and x ₃ of (b) is when it is initially processed is, x ₃ is registered initially in AET as x-coordinate of the edge portions appearing on the scanning line yc. Therefore, after the registration of the AET, the elements of each side in the AET are sorted in ascending order of the x coordinate. Then, two of the first elements of the AET are paired, and the space between them is painted (painting processing using scanning lines). The anti-aliasing process is realized by adjusting the density and brightness of the pixel at the edge portion in the filling process according to the approximate area ratio. Thereafter, the processed side is removed from the AET, the scan line is updated (y coordinate is updated), and the processing is performed until all the sides in the AET are processed, in other words, all the elements in one pass are processed. Is repeated.

The operations 1, 2, and 3 are executed for each pass, and are repeated until all the passes for one page are completed. After the above processing, the printing process of the edge portion is executed by continuously changing the beam power using a laser printer described later. This laser printer is shown in Fig. 1.
As shown in FIG. 1, beam power information nn at the start or end of printing of the edge, width information (width for changing power) mm (pixel) of the edge portion, and control information xx for power increase / decrease are required as information. I do.

Next, a method for generating the above information will be described with reference to FIG. However, it is assumed that all density information is given as values of n stages. First, xx (beam power control signal) is set to 0 (step S801). Next, it is determined whether or not the edge portion has started (step S8).
02), if it is determined that the edge portion has started,
invert x (ie 1 for 0, 0 for 1)
(Step S803). Then, the vector and the scan line (2
The integer part of the x coordinate of the intersection with the book is x0 (x0 is the intersection closer to the image part) and x1 (step S804).

As a result, | x0−x1 | +1 is calculated,
The result is set to mm (width for performing modulation) (step S8).
05).

The density of the pixel where x1 exists is determined in n steps from the area ratio. The result is set to nn (beam power at the start or end of power modulation) (step S806).

Mm, nn, x obtained in the above steps
The value of x is output to the corresponding pixel of the page memory 206 (step S807).

Thereafter, it is determined whether or not one line has been completed (step S808). If not completed, the process proceeds to the next pixel and the operations in steps S801 to S808 are performed until it is determined that one line has been completed. repeat. When it is determined that the process has been completed, a series of operations ends.

If it is determined in step S802 that the edge portion has not started, xx is set to the same value as before (ie, 0 if 0, 1 if 1) (step S809), and Xx is output to the corresponding pixel of the memory 206 (step S810). Thereafter, the operation moves to step S808.

Configuration of Image Processing Apparatus The configuration of the image processing apparatus 400 will be described with reference to FIG. The image processing device 400 is configured to record three color image signals read by the CCDs 7r, 7g, and 7b in the image reading device 300 in black (BK), yellow (Y), magenta (M), and cyan. (C) is converted into each recording signal. In addition, the PDL controller 2
RGB given from the plane memory unit 206a of the 00
The image data is similarly converted into black (BK), yellow (Y), magenta (M), and cyan (C) recording signals. A mode in which an image signal is input from the image reading device 300 is called a copying machine mode, and a 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, 7
g and 7b output color tone data obtained by A / D conversion of the output signal to 8 bits, and uneven optical illuminance of the color tone data and sensitivity variations of the internal terminal elements of the CCDs 7r, 7g and 7b. A shading correction circuit 401 that performs correction for the same, and selectively selects one of color gradation data output from the shading correction circuit 401 or color gradation data (RGB image data) output from the PDL controller 200 in accordance with the above-described mode. And a gamma correction circuit 403 that receives 8-bit data (color gradation data) output from the multiplexer 402, changes gradation according to the characteristics of the photoconductor, and outputs the data as 6-bit data. , Γ correction circuit 403 outputs 6-bit grayscale data representing the grayscales of (R), green (G), and blue (B), respectively. And a complementary color generation circuit 405 that converts the color data into cyan (C), magenta (M), and yellow (Y) gradation data (6 bits), and Y, M, and C output from the complementary color generation circuit 405. A masking processing circuit 406 for performing a predetermined masking process on the tone data, and inputting the Y, M, and C gradation data after the masking process to the UCR
UCR processing / black generation circuit 407 for executing the processing and black generation processing, and the Y, M, C, and BK 6-bit gradation data output from the UCR processing / black generation circuit 407 are converted into 3-bit data. Key data Y, M, C, and BK (in the figure,
Y1, M1, C1, and BK1) and output to the laser drive processing unit 502 inside the multi-valued color laser printer 500.
And a synchronization control circuit 409 for synchronizing each circuit of the image processing apparatus 400. Note that the data in the feature information storage memory unit 206b of the PDL controller 200 is delayed by a predetermined time (a time corresponding to the time required for image processing) without being processed by the image processing device 400. In other words, the image processing device 400 L directly in synchronization with the output of
The data is sent to the D drive processing unit 502.

Although not described in detail, the gamma correction circuit 40
Reference numeral 3 denotes a configuration in which the gradation can be arbitrarily changed by operating buttons on the console 700.

As an algorithm used in the gradation processing circuit 408, a multi-value dither method, a multi-value error diffusion method, or the like can be applied. For example, if the dither matrix of the multi-value dither method is 3 × 3, The number of gradations of the multi-level color laser printer 500 is the product of the area gradation of 3 × 3 and the multi-level level of 3 bits (ie, 8 steps), and 3 × 3 × 8 = 72 (gradation) Become.

Next, the masking processing circuit 406 and the UC
The processing of the R processing / black generation circuit 407 will be described. As an arithmetic expression of the masking process of the masking processing circuit 406, an expression shown in Expression 4 is generally used.

[0063]

(Equation 4)

The UCR processing / black generation circuit 407
The arithmetic expression of the CR process is also generally represented by the expression shown in Expression 5.

[0065]

(Equation 5)

Therefore, in this embodiment, a new coefficient is obtained from these equations by using the product of both coefficients, as shown in Expression 6.

[0067]

(Equation 6)

In this embodiment, the masking process and the UC
A new coefficient (a ₁₁ ″, etc.) for performing the R processing at the same time is calculated and obtained in advance, and the new coefficient is used to calculate the predetermined input values Y _i , M _i , C of the masking processing circuit 406.
An output value (Y ₀ ′ or the like: a value that is a calculation result of the UCR processing / black generation circuit 407) corresponding to _i (6 bits each) is 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 constituted by a set of ROMs, and the data of the address specified by the inputs Y, M, and C of the masking processing circuit 406 is a UCR. Provided as an output of the processing / black generation circuit 407.

Generally speaking, the masking processing circuit 406 corrects the Y, M, and C signals in accordance with the characteristics of the spectral reflection wavelength of the recording image forming toner, and the UCR processing / black generation circuit 407 Performs correction for color balance in superimposition of toners of respective colors. UCR processing
After passing through the black generation circuit 407, the input Y, M, C
Black component data BK is generated by combining the color data, and the output Y, M, and C color component data are corrected to values obtained by subtracting the black component data BK.

Configuration of Multilevel Color Laser Printer (Configuration and Operation of Developing Unit of Multilevel Color Laser Printer) First, referring to a control block diagram shown in FIG. 14, a schematic configuration of a multilevel color laser printer 500 will be described. Will be described.

The photoreceptor development processing unit 501 uniformly charges the surface of a photoreceptor drum described later, forms a latent image by exposing the charged surface with a laser beam, and develops the latent image with toner to form a recording paper. And a black developing / transfer unit 501b that develops and transfers BK data, which will be described in detail later.
k, a cyan developing / transferring unit 501c for developing / transferring C data, a magenta developing / transferring unit 501m for developing / transferring M data, and a yellow developing / transferring unit 501y for developing / transferring Y data. It has.

The laser drive processing unit 502 outputs three of Y, M, C, and BK output from the image processing apparatus 400 described above.
Bit data (here, image density data) is input and a laser beam is output.
Buffer memory 50 for inputting M and C 3-bit data
3y, 503m, 503c, laser diodes 504y, 504m, 504c, 504bk for outputting laser beams corresponding to Y, M, C, BK, and laser diodes 504y, 504m, 504c, 50, respectively.
Drivers 505y and 505 that respectively drive 4bk
m, 505c, and 505bk.

The black developing / transferring unit 501bk of the photoreceptor developing unit 501, the laser driving unit 502, the laser diode 504bk, and the driver 505b
The combination with k is called a black recording unit BKU (see FIG. 15). Similarly, a cyan developing / transferring unit 501c, a laser diode 504c, a driver 505c,
The combination of the buffer memory 503c and the cyan recording unit CU (see FIG. 15), the magenta developing / transferring unit 501m,
The combination of the laser diode 504m, the driver 505m, and the buffer memory 503m is connected to the magenta recording unit MU (see FIG. 15), the yellow developing / transferring unit 50.
1y, laser diode 504y, driver 505
The combination of y and the buffer memory 503y is called a yellow recording unit YU (see FIG. 15). As shown in the drawing, these recording units are arranged in the order of a black recording unit BKU, a cyan recording unit CU, a magenta recording unit MU, and a yellow recording unit YU around a transport belt 506 for transporting the recording paper from the transport direction of the recording paper. Has been established.

According to the arrangement of the recording units, 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 lag between the laser diodes in the order of the exposure start, and during this time lag, the recording data (output of the image processing device 400) is held.
02 has the three sets of buffer memories 503y and 50
3m and 503c are provided.

Next, the configuration of the multi-valued color laser printer 500 will be specifically described with reference to FIG. The multi-level color laser printer 500 includes a transport belt 506 for transporting the recording paper, and a transport belt 50 as described above.
6, each recording unit YU, MU, C
U, BKU, and paper feed cassette 507 containing recording paper
a, 507b and paper feed rollers 508a, 508b for feeding recording paper from paper feed cassettes 507a, 507b, respectively.
And registration rollers 509 for aligning the recording sheets sent out from the sheet cassettes 507 a and 507 b, and the recording units BKU, CU, and M by the transport belt 506.
The image forming apparatus includes a fixing roller 510 that sequentially conveys U and YU and fixes a transferred image on recording paper, and a paper discharge roller 511 that discharges the recording paper to a predetermined discharge unit (not shown). Here, each recording unit YU, MU, CU, BKU
Are photosensitive drums 512y, 512m, 512c, 51
2bk and the photosensitive drums 512y, 512m, respectively.
Charger 513 for uniformly charging 512c and 512bk
y, 513m, 513c, and 513bk, and polygon mirrors 514y and 514 for guiding a laser beam to the photosensitive drums 512y, 512m, 512c, and 512bk.
m, 514c, 514bk and motors 515y, 515
m, 515c, 515bk, and the photosensitive drum 512y,
Toner developing devices 516y, 516m, 516c, 516bk for developing electrostatic latent images formed on 512m, 512c, 512bk using respective color toners
And a transfer charger 5 for transferring the developed toner image to recording paper
17y, 517m, 517c, and 517bk, and the photosensitive drums 512y, 512m, 512c, and 512b after transfer.
Cleaning device 51 that removes toner remaining on k
8y, 518m, 518c, and 518bk. 519y, 519m, 519c, 519bk
Are the photosensitive drums 512y, 512m, and 512m, respectively.
c, a CCD line sensor for reading a predetermined pattern provided on the 512bk.
0 is detected.

The operation of the above configuration will be described by taking exposure, development and transfer of the yellow recording unit YU as an example.
FIGS. 16A and 16B show the configuration of the exposure system of the yellow recording unit YU. In the figure, a laser beam emitted from a laser diode 504y is reflected by a polygon mirror 514y, passes through an f-θ lens 520y, is further reflected by mirrors 521y and 522y, and passes through a dustproof glass 523y to a photosensitive drum 512y. Irradiated. At this time, the laser beam is applied to the polygon mirror 514.
Since y is driven to rotate at a constant speed by the motor 515y, it moves in the direction (main scanning direction) along the axis of the photosensitive drum 512y. In this embodiment, a photo sensor 524y is provided for a laser beam at a non-exposure position in order to detect a base point for tracking a scanning position in the main scanning. Since the laser diode 504y is energized to emit light based on the recording data (3-bit data from the image processing device 400), multi-level exposure corresponding to the recording data is performed on the surface of the photosensitive drum 504y. The surface of the photosensitive drum 504y is uniformly charged in advance by the charger 513y as described above, and the exposure forms an electrostatic latent image corresponding to the original image. The electrostatic latent image is developed by the yellow developing device 516y to become a yellow toner image. This toner image is
As shown in FIG. 15, the cassette 507a (or 5
07b) is fed out by a paper feed roller 508a (or 508b), and is transferred by a registration roller 509 to recording paper conveyed by a conveyance belt 506 in synchronization with the toner image formation of the black recording unit BKU.

The other recording units BKU, CU, and MU perform the same operation with the same configuration, but the black recording unit BKU includes a black toner developing device 516bk to form and transfer a black toner image, and The recording unit CU includes a cyan toner developing device 516c and forms and transfers a cyan toner image. The magenta recording unit MU includes a magenta toner developing device 516m and forms and transfers a magenta toner image.

Multi-value driving of drivers Drivers 505y, 505m, 505c, 505bk
Are Y1, M1, and
Based on the 3-bit data of C1, BK1, the corresponding laser diodes 504y, 504m, 504c, 50
Control for multi-value driving of 4bk is performed, and the driving method in this embodiment is a power modulation method as described above.

Hereinafter, multi-value driving by power modulation applied in the first embodiment will be described in detail with reference to FIG. The drivers 505y, 505m, 505c, and 505bk and the laser diodes 504y, 504m, and 504
Since c and 504bk have the same configuration, the driver 505y and the laser diode 504 are used here.
This will be described using y as an example.

As shown in FIG. 17, the driver 505y has 3-bit image density data (here, Y1 data) and a 1-bit beam power control signal xx.
(Power control), the laser diode 504y is turned off based on a predetermined LD drive clock (pixel clock).
Laser diode on / off circuit 5 for n / off
50 and a D / A for converting a digital signal to an analog signal
The converter 551 and a constant current circuit 552 which receives an analog signal based on the image density value from the D / A converter 551 and supplies a current (LD driving current) Id for driving the laser diode 504y to the laser diode on / off circuit 550. And a gradient information generation LUT (lookup table) 553 for outputting a gradient selection signal, and an integration circuit 554 for inputting the gradient selection signal from the gradient information generation LUT 553 and selecting an appropriate time constant. You.

FIG. 18 shows the laser diode on / o.
A specific circuit diagram of the ff circuit 550 and the constant current circuit 552 is shown. The laser diode on / off circuit 550 is
D flip-flop 570 and TTL inverter 57
1, 572, differential switching circuits 555 and 556 that perform on / off toggle operation, and when VG1> VG2, the differential switching circuit 555 is on, the differential switching circuit 556 is off, and VG1 <VG2. At this time, the differential switching circuit 555 is composed of resistors R ₂ and R ₃ forming a voltage dividing circuit that generates VG2 satisfying the condition that the differential switching circuit 555 is turned off and the differential switching circuit 556 is turned on.

In the laser diode on / off circuit 550, the Q output of the D flip-flop 570 is H
At this time, Q ₁ turns on and Q ₂ turns off. Current Id flowing through the Q ₁ is generated by the constant current circuit 552 (see FIG. 19).

As described above, the constant current circuit 552 supplies the current of the laser diode 504y to the laser diode on / off circuit 550, and includes a transistor 560 and resistors R ₄ and R ₅ . D
/ Output Vd from the A converter 551 (control current) is applied to the base of the transistor 560, it determines the voltage applied to the resistor R _4. In other words, as shown in FIG. 20, the control voltage Vd and the collector current of the transistor 560 are in a proportional relationship, and therefore, the current flowing through the laser diode 504y is controlled by the control voltage Vd.

The D / A converter 551 has a latch 557 for latching the input image density data while the LD drive clock is "1" as shown in FIG. 21, and a 3-bit D / A converter 559 for outputting the analog data Vd. It is composed of

The beam power value nn (here, 3 bits) is held by the latch 557 at the rising edge of the pixel clock. The output from the latch 557 is a 3-bit D /
The signal is input to the A converter 559. This 3-bit D / A
The converter 559 divides the potential difference between V _{ref +} and V _ref- , outputs a voltage according to the input, and is applied to the power interruption grain circuit 552 via the resistor _RA . FIG. 22 shows the beam power nn.
And the relationship between the pixel clock and the D / A converter output.

The integration circuit 554 generates an integrated waveform in relation to the power control xx, and the relation is shown in FIG. In the figure, the slope generated at the output of the integration circuit 554 is determined by the output of the slope information generation LUT.

The inclination information generation LUT 553 is shown in FIG.
The slope shown in (a) is calculated in advance using Equation 7.

[0088]

(Equation 7)

The inclination selection signal of the inclination information generation LUT 553 is output to the integration circuit 554.

As shown in FIG. 24B, the beam power nn is 3 bits = 8 values, and the number of edge pixels mm is 3
Bit = 8 values, 3-bit image density data (here,
Assuming that Y1 data) is 3 bits = 8 values, the gradient selection signal has 9 bits = 512 values.

The integration circuit 554 is connected to a time constant circuit 554a as shown in FIG.
There are twelve types, and those time constants are selected as appropriate according to the gradient selection signal. Finally, the output voltage from the D / A converter 551 and the output voltage of the integration circuit 554 are added via respective resistors to generate a control voltage Vd.

Specific Operation Example A specific operation example of the present invention will be described with reference to FIGS. 26 (a), 26 (b) and 26 (c). In this example, the density is set to eight levels. The vector of (1) in FIG. 26A is a starting point,
End points (7, 3) and (2, 5), and the vector of (2) in FIG. 9A is a start point, end points (7, 3), (9,
6), and the vector of (3) in FIG.
End points (2, 5) and (9, 6). In scan line processing between y = 3 and 4 scan lines, the vector (1) is X
1 = 4.5, X0 = 7.0 has an intersection, and vector (2) has an intersection at X0 = 7.0, X1 = 7.6.

In this scan line, x = 0 to x =
Up to 3, there is no edge and xx = 0. x = 4
For the first time, there is an edge at pixel xx, and xx = 1.
The pixel density is calculated as nn = 1, and the pixel with an edge continues for three pixels, so that mm = 3. These pieces of information are written into the feature information storage memory unit 206b of the page memory 206 as needed. Such an operation,
This is performed for each scan line.

FIG. 26 shows the information of the page memory 206 corresponding to the pixels existing at 3 ≦ Y ≦ 5 and 1 ≦ X ≦ 9 in FIG.
(B). The output image according to this information is shown in FIG.
(C) is obtained. When the right edge and the left edge exist in the same pixel, as in the scan line between y = 5 and y = 6, first, writing is performed up to the immediately preceding pixel according to the left edge information. From the pixel, the writing process is executed based on the information of the right edge.

By setting the density information to n levels by the above operation, it is possible to avoid the conventional disadvantage that the modulated density changes stepwise for each pixel, and to reduce the number of pixels for which anti-aliasing processing is performed. than as possible out to reduce also, to a high speed, and can be obtained efficiently antialiasing image.

[Embodiment 2] Next, Embodiment 2 of the graphic output apparatus of the present invention will be described in detail in the order of anti-aliasing processing, multi-value driving of a driver, and a specific operation example with reference to the drawings. The configuration of the second embodiment is similar to that of the first embodiment except that the drivers 560y, 560m, 560c, and 560c described later are replaced with the drivers 505y, 505m, 505c, and 505bk.
Except for using 60bk, illustration and description are omitted because they are common to the first embodiment.

Anti-Aliasing Process In the second embodiment, instead of executing the area ratio calculation in the anti-aliasing process, the width information m of the edge portion is used.
m, the control information xx of the power increase / decrease start position and the fine start position information aa in the pixel of the power increase / decrease start position are generated as the anti-aliasing processing result, and the anti-aliasing processing result (mm, xx, three information of aa)
When outputting, the end pixel (pixel) at each edge
From the minimum value to the predetermined value (Y1 sent from the image processing device 400,
By performing modulation toward (value based on 3-bit data of M1, C1, and BK1), an image subjected to anti-aliasing processing can be obtained at high speed and efficiently.

FIG. 27 shows a state where a laser printer is used.
Three pieces of information used when the beam power is continuously changed from the minimum value to the maximum value (or from the maximum value to the minimum value) to execute the printing process of the edge portion, and the minimum value and the maximum value of the beam power Shows the relationship with the value, as shown in the figure,
Fine start position information aa in the pixel of the power increase / decrease start position in the pixel (here, pixel 1) specified by the control information xx of the power increase / decrease start position
A configuration in which the beam power is continuously changed from the minimum value to a predetermined value from the position specified by (0 or more and 1 or less) to the width specified by the width information (power changing width) mm (pixel) of the edge portion. It is.

Next, an anti-aliasing method for generating the above information will be described with reference to FIG. However, it is assumed that all density information is given as values of n stages.

First, xx (beam power control signal) is set to 0 (step S301). Next, it is determined whether the edge portion has started (step S30).
2) If it is determined that the edge portion has started, the above xx
(That is, 1 if 0, 1 if 1) (step S303). After that, vectors and scanning lines (2 lines)
The x coordinate of the intersection with x is x0 (x0 is the intersection closer to the image portion) and x1 (step S304).

As a result, | x0−x1 | is calculated, and the fractional part of the result in the form of a multiple of 1 / (n−1) is expressed in mm (modulation width 1 / (n−1) unit). ) (Step S305).

It is determined whether the edge is a left edge or a right edge (step S306). As a result, when it is determined that the left edge is the left edge, the decimal part of x1 is formed into a multiple of 1 / (n-1). This is defined as a1 (step S30)
7). This a1 is defined as aa (a beam modulation start position 1 / (n-1) unit in one pixel) (step S30).
8).

If it is determined in step S306 that the right edge is present, the decimal part of x0 is changed to 1 / (n−
Make it a multiple of 1). This is defined as a0 (step S
309). This a0 is defined as aa (a beam modulation start position 1 / (n-1) unit in one pixel) (step S31).
0).

Mm, aa, x obtained in the above steps
The value of x is output to the corresponding pixel of the page memory 206 (step S311).

Thereafter, it is determined whether or not one line has been completed (step S312). If not completed, the process proceeds to the next pixel and the operations from steps S301 to S312 are performed until it is determined that one line has been completed. repeat. When it is determined that the process has been completed, a series of operations ends.

If it is determined in step S302 that the edge has not started, xx is set to the same value as before (ie, 0 if 0, 1 if 1) (step S313), and the page Xx is output to the corresponding pixel of the memory 206 (step S314). Thereafter, the operation moves to step S312.

Multi-Level Driving of Driver In the second embodiment, the drivers 505y and 505 of the first embodiment are used.
m, 505c, 505bk
60y, 560m, 560c and 560bk are used.

Drivers 560y, 560m, 560c,
560bk is the Y transmitted from the image processing apparatus 400.
Based on 3-bit data of 1, M1, C1, and BK1,
Applicable laser diode 504y, 504m, 50
4c and 504bk are controlled to perform multi-value driving, and the driving method in the present embodiment is a power modulation method as described above.

Hereinafter, multi-value driving by power modulation applied in the second embodiment will be described in detail with reference to FIG. The drivers 560y, 560m, 560c, and 560bk, and the laser diodes 504y, 504m, and 504
Since c and 504bk have the same configuration, the driver 560y and the laser diode 504 are used here.
This will be described using y as an example.

As shown in FIG. 29, the driver 505y turns on / off the laser diode 504y based on a 1-bit beam power control signal xx (power control) and a predetermined LD drive clock (pixel clock).
Laser diode on / off circuit 561 to turn off
And a delay circuit 562 for delaying the pixel clock, and a current (LD drive current) Id for driving the laser diode 504y is supplied to the laser diode on / off circuit 561.
Constant current circuit 563 for supplying a gradient selection signal and a gradient information generation LUT (lookup table) 564 for outputting a gradient selection signal
And an integration circuit 565 that receives a gradient selection signal from the gradient information generation LUT 564 and selects an appropriate time constant.

The timing chart of FIG. 30 shows the pixel clock, edge sub-pixel information aa, and delay circuit 5
The relationship between the delayed pixel clocks output via 62 is shown. The delay amount is determined by the edge sub-pixel information aa. The actual delay is performed by delay circuit 562. Note that td in the figure is a value determined in the pixel by the edge sub-pixel information aa, and in this case, td = 1 pixel period / 8.

Specific Operation Example A specific operation example of the second embodiment will be described with reference to FIGS. 31 (a), 31 (b) and 31 (c). In this example, the density is set to eight levels. The vector of (1) in FIG. 31A is a start point and an end point (7, 3) and (2, 5), and the vector of (2) in FIG. 31A is a start point and an end point (7, 3). ), (9,
6), and the vector of (3) in FIG.
End points (2, 5) and (9, 6). In scan line processing between y = 3 and 4 scan lines, the vector (1) is X
1 = 4.5, X0 = 7.0 has an intersection, and vector (2) has an intersection at X0 = 7.0, X1 = 7.6.

In this scan line, x = 0 to x =
Up to 3, since no edge appears, xx = 0. x
= 4 pixels have an edge for the first time, and xx = 1. Pixels with an edge are 2.5 at 7.0-4.5
Since 0.5 follows the pixel, 0.5 is shown as a multiple of 1/7 and 4
/ 7 and mm = 2 + 4/7. Further, when the decimal part of X1 is set to n stages, aa = 4/7.

These information are written in the page memory 206 as needed. Only xx = 1 is written to the pixels of x = 5,6. At the pixel of x = 7, a second edge appears and xx = 0 and xx are inverted. The edge is 7.6-7.
At 0, the pixel continues for 0.6 pixels, but when it is a multiple of 1/7, mm = 5/7. Since the decimal part of 7.0 is 0.0, aa = 0.

Since no edge appears at the pixels of xx = 8 and 9, only the information of xx = 0 is written in the page memory.

Such an operation is performed for each scan line. 3 ≦ Y ≦ 5, 1 ≦ X shown in FIG.
Page memory 206 corresponding to pixels existing in ≦ 9
FIG. 31 (b) shows the information inside. An output example based on the information in the page memory 206 shown in FIG.
It is shown in (c).

When the right edge and the left edge exist in the same pixel as in a scan line between y = 5 and y = 6, first, writing is performed up to the pixel by the information of the left edge. The right edge information is overwritten with the pixel and writing is performed (that is, the right edge information has priority).

As described above, by setting the density information to n levels, it is possible to avoid the conventional disadvantage that the modulated density changes stepwise for each pixel, and to execute the area ratio calculation for the pixel. Therefore, a high-quality image that has been subjected to anti-aliasing processing at high speed can be obtained.

Third Embodiment Next, a third embodiment of the graphic output apparatus of the present invention will be described in detail in the order of anti-aliasing processing, multi-value driving of a driver, and a specific operation example with reference to the drawings. The configuration of the third embodiment is similar to that of the first embodiment except that the drivers 505y, 505m, 505c, and 505bk of the first embodiment are replaced with drivers 570y, 570m, 570c,
Except for using 70bk, illustration and description are omitted because they are common to the first embodiment.

Anti-Aliasing Process In the third embodiment, instead of performing the area ratio calculation in the anti-aliasing process, the beam power information nn, the width information mm of the edge portion, and the power increase / decrease at the start or end of edge printing are changed. Control information xx of the start position,
In addition, a fine start position aa in a pixel at a power increase / decrease start position is generated as an anti-aliasing processing result, and the laser beam printer outputs the anti-aliasing processing result (four pieces of information of nn, mm, xx, and aa). At this time, by continuously modulating the beam power from the end pixel (pixel) at each edge to the image portion, it is possible to obtain an anti-aliased image at high speed and efficiently. It is.

FIG. 32 shows a state where a laser printer is used.
The relationship between four pieces of information used when executing the printing process of the edge portion by continuously changing the beam power is shown. As shown in the figure, the pixel () designated by the control information xx of the power increase / decrease start position Here, from the position specified by the fine start position information aa (0 or more and 1 or less) in the pixel of the power increase / decrease start position in the pixel 1), the width information of the edge portion (the width for changing the power) mm (pixel) ), The beam power is changed to the background beam power information nn (at the start of power modulation, or
(Information on the beam power at the end: base power information) is continuously changed to the image density. Note that cc shown in the figure indicates a power modulation width from nn to the image portion, and corresponds to a value obtained by subtracting nn from the image portion density.

Next, an anti-aliasing method for generating the above information will be described with reference to FIG. However, it is assumed that all density information is given as values of n stages.
First, xx (beam power control signal) is set to 0 (step S321). Next, it is determined whether or not the edge has started (step S322). If it is determined that the edge has started, the xx is inverted (that is, 1 if 0, 1 if 1). (Step S32
3). Then, x at the intersection of the vector and the scanning line (two lines)
The coordinates are x0 (x0 is the intersection point closer to the image part) and x1 (step S324).

As a result, | x0−x1 | is calculated, and the decimal part of the result in the form of a multiple of 1 / (n−1) is expressed in mm (modulation width 1 / (n−1) unit). ) (Step S325).

It is determined whether the edge is a left edge or a right edge (step S326). As a result, when it is determined that the left edge is the left edge, the decimal part of x1 is formed into a multiple of 1 / (n-1). This is referred to as a1 (step S32)
7). This a1 is defined as aa (a beam modulation start position 1 / (n-1) unit within one pixel) (step S32).
8).

If it is determined in step S326 that the right edge is present, the decimal part of x0 is changed to 1 / (n−
Make it a multiple of 1). This is defined as a0 (step S
329). This a0 is defined as aa (the beam modulation start position within one pixel 1 / (n-1) unit) (step S33).
0).

Further, the pixel densities immediately before and immediately after the edge portion are defined as C1 and C2 (step S331), and | C1-C
2 | is set to cc (step S332). Then, C1
> C2 (step S333), and when it is determined that C1> C2, C2 becomes nn (step S333).
334). Conversely, when it is determined that C1> C2 is not satisfied, C1 becomes nn (step S335).

The mm, aa, c obtained in the above steps
The values of c, nn, and xx are output to the corresponding pixels of the page memory 206 (step S336). Thereafter, it is determined whether or not one line is completed (step S337). If not completed, the process proceeds to the next pixel and step S32 is performed.
The operations from 1 to S337 are repeated until it is determined that one line is completed. When it is determined that the process has been completed, a series of operations ends.

If it is determined in step S322 that the edge portion has not started, xx is set to the same value as before (ie, 0 if 0, 1 if 1) (step S338), and Xx is output to the corresponding pixel of the memory 206 (step S339). Thereafter, the operation moves to step S337.

Driver Multi-Valued Driver Drivers 570y, 570m, 570c, 570bk
Are Y1, M1, and
Based on the 3-bit data of C1, BK1, the corresponding laser diodes 504y, 504m, 504c, 50
Control for multi-value driving of 4bk is performed, and the driving method in this embodiment is a power modulation method as described above.

Hereinafter, multi-value driving by power modulation applied in the third embodiment will be described in detail with reference to FIG. The drivers 570y, 570m, 570c, 570bk, and the laser diodes 504y, 504m, 504
Since c and 504bk have the same configuration, the driver 570y and the laser diode 504 are used here.
This will be described using y as an example.

As shown in FIG. 34, the driver 570y includes a laser diode on / off circuit 571 for turning on / off the laser diode 570y based on a predetermined LD drive clock, and 3-bit image density data (here, A D / A converter 572 for converting the Y data) into an analog signal, and a current (LD drive current) for inputting an analog signal based on the image density value from the D / A converter 572 to drive the laser diode 570y.
A constant current circuit 573 for supplying Id to the laser diode on / off circuit 571, a gradient information generation LUT (lookup table) 574 for outputting a gradient selection signal,
It comprises an integration circuit 575 for inputting a gradient selection signal from the gradient information generation LUT 574 and selecting an appropriate time constant, and a delay circuit 576.

FIG. 35 shows the laser diode on / o.
A specific circuit diagram of the ff circuit 571 and the constant current circuit 573 is shown. The laser diode on / off circuit 571 is
D flip-flop 581 and TTL inverter 58
2, 583, and differential switching circuits 578 and 577 that perform on / off toggle operations, and when VG1> VG2, the differential switching circuit 578 is on, the differential switching circuit 577 is off, and VG1 <VG2. In this case, the differential switching circuit 276 is composed of resistors R ₂ and R ₃ forming a voltage dividing circuit that generates VG2 satisfying the condition that the differential switching circuit 577 is turned off and the differential switching circuit 577 is turned on.

In the laser diode on / off circuit 571, the Q output of the D flip-flop 581 is H
At this time, Q ₁ turns on and Q ₂ turns off. Current Id flowing through the Q ₁ is generated by the constant current circuit 573 (see FIG. 36). The constant current circuit 573 supplies the current of the laser diode 570y to the laser diode on / off circuit 571 as described above, and includes a transistor 580 and resistors R ₄ and R ₅ . The output Vd of the D / A converter 572 (control current) is applied to the base of the transistor 580, it determines the voltage applied to the resistor R _4. In other words, FIG.
The control voltage Vd is proportional to the collector current of the transistor 580 as shown in FIG.
This controls the current flowing through the laser diode 570y.

FIG. 38 is a timing chart showing the relationship between the pixel clock and the delayed pixel clock. This delay amount is determined by the edge sub-pixel information aa. The actual delay is implemented by a delay circuit. In addition, t in the figure
d is a value determined in the pixel by the edge sub-pixel information aa. In this case, td = 1 pixel period / 8.

As shown in FIG. 39, D / A converter 57
Reference numeral 2 denotes a latch 572a for latching input image density data while the LD drive clock is "1", and a 3-bit D / A converter 572b for outputting analog data Vd.
It is composed of

The beam power value nn (here, 3 bits) is held by the latch 557 at the rising edge of the delayed pixel clock. The output from the latch 557 is input to the 3-bit D / A converter 559. This 3 bit D
The / A converter 559 divides the potential difference between V _{ref +} and V _ref− , outputs a voltage according to the input, and is applied to the constant current circuit 573 via the resistor _RA . FIG. 40 shows the relationship between the beam power nn, the pixel clock, and the D / A converter output.

The integration circuit 575 is for generating an integration waveform in relation to the power control xx, and the relation is shown in FIG. In the figure, the slope generated at the output of the integration circuit 575 is determined by the output of the slope information generation LUT 574. The inclination information generation LUT 574 calculates the inclination shown in FIG.

[0138]

(Equation 8)

The inclination selection signal of the inclination information generation LUT 574 is output to the integration circuit 575.

As shown in FIG. 42B, the beam power nn is 3 bits = 8 values, and the number of edge pixels mm is 3
Bit = 8 values, 3-bit image density data (here,
If Y1 data) is 3 bits = 8 values and the edge subpixel aa is 3 bits = 8 values, the inclination selection signal is 12 bits = 4096 values.

The integration circuit 575 is connected to a time constant circuit 575a as shown in FIG.
There are twelve types, and those time constants are selected as appropriate according to the gradient selection signal. Finally, the output voltage from the D / A converter 572 and the output voltage of the integration circuit 575 are each added via a resistor to generate a control voltage Vd.

Specific Operation Example A specific operation example of the present invention will be described with reference to FIGS. 44 (a), (b) and (c). In this example, the density is set to eight levels. FIG. 44A shows two vectors (1) and (2). In scan line processing between y = 3 and 4 scan lines, the vector (1) has X1 = 3.3 and X0 = 3.
6, the vector (2) is X0 = 5.2, X1
= 6.7. In this figure, it is assumed that the density of the graphic at the left end is 2, the density of the graphic at the center is 6, and the density of the graphic at the right end is 4.

In this scan line, x = 0 to x =
For up to two pixels, since no edge has appeared, x
x = 0. However, as base power, nn = 2
Is given to the pixel of x = 0. An edge exists for the first time at the pixel of x = 3, and inverts to xx = 1.

Pixels with an edge are 3.6-3.3.
Since 0.3 continues for 0.3 pixels, 0.3 is represented by a multiple of 1/7, and is set to 2/7, so that mm = 2/7. Further, when the decimal part of X1 is set to n stages, aa = 2/7. At this edge, the power must change from 2 to 6, so cc = 6-2 = 4 is given as the power change width.

The information is written into the page memory 206 as needed. Based on these pieces of information, in the case of the pixel of x = 3, an edge is expressed by adding a triangular wave whose power is increased by 4 in 2/7 pixels and a waveform whose power is always 2 together. Pixels with x = 4 write only xx = 1. At a pixel of x = 5, a second edge appears, and x
x = 0 and xx are inverted.

The edge is 6.7-5.2 and continues for 1.5 pixels, and when it is rounded to a multiple of 1/7, mm = 1
+3/7. Since the decimal part of 5.2 is 0.2, aa
= 1/7. As for the base power nn of the edge, the pixel immediately after the edge along the scan line has a density of 4.

As in the case of the left edge, the power change width cc
Is 2 in 6-4. Since no edge appears at the pixel of x = 7, only the information of xx = 0 is stored in the page memory 206.
Write to.

The above operation is executed for each scan line. The information of the page memory 206 corresponding to the pixels existing at 2 ≦ Y ≦ 5 and 0 ≦ Y ≦ 7 in FIG.
(B). FIG. 44C shows an output example based on the information shown in FIG.

When two or more vectors exist in one pixel, as in the case of y = 2, 3 scan lines, the last pixel among the pixels is located at the corresponding pixel position in the page memory 206. Edge information to be line-processed is written.

By the above method, it is possible to avoid the conventional disadvantage that the density modulated by changing the density information into n steps changes step by step for each pixel, and it is also possible to calculate the area ratio of each pixel. Since this is not performed, a high-quality image that has been subjected to anti-aliasing processing at high speed can be obtained.

Further, according to the present invention, it is possible to perform anti-aliasing processing of an edge portion without performing read-modify-write of a page memory for drawing or the like having a halftone background, so that overwriting can be performed. Various problems due to the processing can be solved.

[Embodiment 4] Embodiments 1 to 3 described above.
In the graphic output device of (1), image data composed of a set of vector data is targeted. In the fourth embodiment, image data composed of bit pattern images is targeted, and image continuity is ensured. An object of the present invention is to provide a graphic output device that outputs high quality.

FIG. 45 is a schematic configuration diagram of a graphic output device according to the fourth embodiment. The CPU 801 controls the entire device according to various control programs, a ROM 802 storing various control programs used by the CPU 801, and a control program. RAM 803 for temporarily storing and reading data to be used in a computer, a character generator 804 for converting character code data into a bit pattern, and a device for inputting image data from an external device such as a personal computer. An I / F 805, a page memory 806 for storing image data for one page (here, data in pixel units), and dot data of a predetermined size are read from the image data stored in the page memory 806; Line buffer 8 composed of FIFO memory for storing
07, a comparison circuit 808 that compares a bit pattern of a certain size read to the line buffer 807 with a basic pattern stored in advance (to be described in detail later), and outputs compensation data when they match. A compensation signal generation circuit (beam power modulation processing means of the present invention) 809 which receives compensation data of the circuit 808 and generates a compensation signal for a pixel of interest; and a laser drive circuit 810 which outputs a laser beam based on the compensation signal. Image forming process for outputting a latent image created by a laser beam to recording paper 8
And 11.

FIGS. 46A and 47A show an example of the basic pattern stored in the comparison circuit 808 in advance. In the fourth embodiment, as a basic pattern, m
Using a pattern of × n (m, n; an integer of 0 or more), a comparison circuit 808 compares these with the bit pattern read into the line buffer 807. FIG. 46 (b)
And FIG. 47 (b) visually shows processing performed when the bit pattern and the basic pattern match,
FIGS. 46C and 47C are enlarged views of the pixel of interest at that time.

Taking the basic pattern shown in FIG. 46A as an example, the comparison circuit 808 applies a beam
Compensation data SS consisting of two pieces of information: power modulation start position information and information indicating to what pixel the beam power is to be modulated, and a pulse for designating whether to perform pulse position modulation or beam power modulation. It outputs a position modulation / beam power modulation switching signal S1. A compensation signal generation circuit 809, which will be described later, changes the laser beam output based on the compensation data SS and the pulse position modulation / beam power modulation switching signal S1, thereby changing the laser beam output to a predetermined dot diameter. A beam power modulation process for hitting smaller dots is performed, and a beam modulation start position is controlled. Regarding the beam modulation start position, when the length of one dot is l, k _s (0 ≦ k _s <
1: k _s , 1 is an integer). In this embodiment,
By pulse position modulation and beam power modulation switching signal S1 and the beam modulation start position k _s, to identify the modulation start position of the beam power, until the pixel specified by the information indicating whether to modulate the beam power to which pixel from the position During this period, the beam power is changed from the minimum value to the maximum value and output.

On the other hand, taking the basic pattern shown in FIG. 46B as an example, the comparison circuit 808 modulates beam power modulation stop position information for the pixel of interest and the beam power to which pixel. Compensation data SS consisting of two pieces of information indicating whether or not, and a pulse position modulation / beam power modulation switching signal S1 are output. A compensation signal generation circuit 809, which will be described later, performs a beam power modulation process of changing the laser beam output by changing the laser driving current based on the compensation data SS to strike a dot smaller than a predetermined dot diameter. , And further controls the beam modulation stop position. Regarding the beam modulation stop position, 1
When the length of the dot is l, k _e (0 ≦ k _e <1:
k _e , 1 is an integer). Here identifies modulation start pixel of beam power based on pulse position modulation and beam power modulation switching signal S1, designated by the information, and the beam modulation stop position k _e indicates whether to modulate the beam power to which the pixel from the pixel Until the position
The beam power is changed and output from the maximum value to the minimum value.

The comparing circuit 808 outputs the pulse position modulation / beam power modulation switching signal S1 in addition to the compensation data SS as described above. The pulse position modulation is performed as shown in FIG.
As shown in (a), the position of the dot is changed by shifting the drive current pulse for turning on or off the laser from the position where the laser should be turned on or off earlier or later in time. The beam power modulation is a process of changing the laser beam output by changing the current value for driving the laser to form dots smaller than a predetermined dot diameter, as shown in FIG. In the fourth embodiment, in the latter beam power modulation,
As shown in FIG. 48C, the laser beam output is continuously changed. In this case, whether the pulse position modulation or the beam power modulation is performed is determined based on the basic pattern matched in the comparison circuit 808 described above.

FIG. 49 shows the structure of the compensation signal generating circuit 809. The output from the comparison circuit 808, that is, the compensation data SS for the pixel of interest and the pulse position modulation / beam power modulation switching signal S1 are input to this circuit via three-state buffers 809a and 809b, respectively.
The reason why the three-state buffers 809a and 809b are used here is that the beam power modulation is continuously performed over three or more pixels as in the example of FIG. Is determined by the compensation data SS (information indicating up to which pixel the beam power is to be modulated) given when the pixel serving as the starting point is processed as the pixel of interest. This is because the compensation data SS for the pixel located between the start point and the end point is not necessary, and the input from the comparison circuit 808 is prohibited at that time.

FIG. 50 shows the pixels for which the compensation data SS is read in blank, as shown in the figure, for the pixels between the beam power modulation start pixel and the beam power modulation end pixel.
Therefore, when the compensation data SS at the time when the pixel serving as the starting point of the beam power modulation is set as the target pixel is input to the beam power modulation information generation LUT 809f, the start beam power S4, the gradient S5 of the beam power change, and An empty data read signal S6 is output.
Becomes High level for a predetermined time (time until the laser beam finishes scanning between the start point and the end point), whereby the three-state buffers 809a and 809b enter a high impedance state, and the comparison circuit 808 sends the compensation signal generation circuit The input of the compensation data SS and the pulse position modulation / beam power modulation switching signal S1 to 809 is cut off.
While this input is cut off, the integrating circuit 80 having an appropriate time constant corresponding to the gradient S5 of the beam power change output from the beam power modulation information generation LUT 809f.
9h is selected, and a current value from the current value corresponding to the starting beam power S4 to the current value corresponding to the maximum beam power is supplied from the constant current circuit 809g according to the time constant, and the laser diode is driven by the laser driving circuit 810. A laser beam is emitted from 810a.

On the other hand, when pulse position modulation is performed, 3
The state buffers 809a and 809b are data-through. One compensation data is always input to the pulse position modulation information generation LUT 809d for one target pixel, and the pulse position S2 and beam power S3 output therefrom are output. , A laser drive pulse is output from the pulse generation circuit 809e.

FIG. 51 shows that the processing mode of the pixel of interest is
4 shows a timing chart of the compensation signal generation circuit 809 in the case of power modulation processing. The compensation signal generation circuit 809
It operates in synchronization with the pixel clock, and dot data is sequentially processed according to the operation. For example, in state T1, 3
Since the data empty reading signal S6 for controlling the state buffers 809a and 809b is active, when the pixel clock rises, the compensation data SS and the switching signal S1 for a certain target pixel are input. The input data determines the starting beam power modulation and the gradient of the beam power change, and the waveform of the laser drive current starts to change. At the same time, the data idle reading signal S1 falls and maintains its output for a certain period according to the contents of the compensation data SS, during which the three-state buffers 809a and 809
09b becomes non-active, and subsequent data input is cut off even if the pixel clock rises (state T
2 and state T3). However, the laser drive current continues to increase between the state T2 and the state T3. When the state T3 is reached, the laser drive current settles to a current value corresponding to the maximum beam power. The amount of change in the laser drive current value at this time is (I _max -I
_min ). Here, at the same time as the maximum current value is settled,
The data empty reading signal S1 rises, the data input cutoff state is released, and the circuit enters the data through state. In the state T4, the circuit waits for input of the compensation data SS to a new target pixel.

As described above, in the fourth embodiment, since the pixel value of the portion to be compensated for, such as the step change of the dots in the bit pattern image, is continuously changed, it is possible to output the bit pattern image with high quality. Can be.

[0163]

As described above, according to the graphic processing apparatus of the present invention, when outputting the anti-aliasing processing result in the laser beam printer, only the density of the end pixel (pixel) at each edge is output. Is obtained by an anti-aliasing process, and the modulation from the pixel to the image portion is performed by continuously changing the beam power toward the maximum value, so that the continuity of the image is ensured. By reducing the number of pixels to be processed, it is possible to obtain an anti-aliased image at high speed and effectively.

Further, according to the graphic processing apparatus of the present invention, in the laser beam printer, when outputting the result of the anti-aliasing processing, the power of the beam is continuously changed from the end pixel (pixel) to the image portion at each edge. The modulation is performed from the minimum value to the maximum value. At this time, the start position and the end position of the beam power change are set to a width smaller than 1 pixel (1 / (n−
1) control by the pixel width) to ensure continuity of the image, and to obtain an anti-aliased image at high speed and efficiently without executing the area ratio calculation for the anti-aliasing process. Can be.

Further, according to the graphic processing apparatus of the present invention, in the laser beam printer, the anti-aliasing processing is performed by executing the anti-aliasing processing at the end pixel (pixel) at each edge.
It is performed by continuously modulating the power of the beam from to the image part, and the modulation range of the beam power is
It is determined by the pixel density immediately before and after several pixels with an edge on the scan line. Furthermore, since the start position and the end position of the beam power change are controlled with a width smaller than 1 pixel (1 / (n-1) pixel width in the case of n-stage density expression), continuity of the image is ensured.
An anti-aliased image can be obtained quickly and efficiently without performing the area ratio calculation in the anti-aliasing process.

Further, according to the graphic processing device of the present invention, the image data of the bit pattern image
A graphic output device for generating compensation data by comparing the bit map with a predetermined pattern stored in advance, and combining and outputting the image data and the compensation data to improve the image quality of an output image; Based on the data, the laser beam power of the portion to be compensated for the image data is changed to a laser beam of a dot smaller than a predetermined dot diameter.
Since beam power modulation processing means for continuously modulating and outputting the beam is provided, the continuity of the image is ensured and the image data of the bit pattern image can be output with high quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an image forming system according to a first embodiment.

FIG. 2 is an explanatory diagram showing an anti-aliasing process by a uniform averaging method.

FIG. 3 is an explanatory diagram showing an anti-aliasing process by a weighted averaging method.

FIG. 4 is an explanatory diagram showing an example of a filter used in a weighted averaging method.

FIG. 5 is an explanatory diagram showing a convolution integration method with reference to 3 × 3 pixels.

FIG. 6 is an explanatory diagram showing an anti-aliasing process for obtaining an approximate area ratio of an edge portion pixel.

FIG. 7 is an explanatory diagram showing an anti-aliasing process for obtaining an approximate area ratio of an edge portion pixel.

FIG. 8 is an explanatory diagram showing a configuration of a PDL controller.

FIG. 9 is an explanatory diagram showing a configuration of a page memory.

FIG. 10 is a flowchart showing the operation of the PDL controller and an explanatory diagram showing a path painting process.

FIG. 11 is an explanatory diagram illustrating information necessary for the operation of the first embodiment.

FIG. 12 is a flowchart illustrating an anti-aliasing process according to the first embodiment.

FIG. 13 is an explanatory diagram illustrating a configuration of an image processing apparatus.

FIG. 14 is a control block diagram illustrating a multi-level color laser printer.

FIG. 15 is an explanatory diagram illustrating a configuration of a multi-level color laser printer.

FIG. 16 is an explanatory diagram showing a configuration of an exposure system of a yellow recording unit.

FIG. 17 is an explanatory diagram showing multi-level driving by power modulation.

FIG. 18 shows the laser diode on / o shown in FIG.
FIG. 3 is a circuit diagram illustrating details of an ff circuit and a constant current circuit.

FIG. 19 is a timing chart showing the relationship between power control based on the Q output of a D flip-flop and a pixel clock.

FIG. 20 is an explanatory diagram showing a relationship between a control voltage and a laser diode current.

FIG. 21 is a circuit diagram showing a configuration of a D / A converter.

FIG. 22 is a timing chart showing a relationship between a beam power and a pixel clock.

FIG. 23 is a timing chart showing the relationship between the power control and the output of the integration circuit.

FIG. 24 is an explanatory diagram showing an operation and a configuration of a tilt information generation LUT.

FIG. 25 is an explanatory diagram showing a configuration of an integration circuit.

FIG. 26 is an explanatory diagram illustrating a specific operation example of the first embodiment.

FIG. 27 is an explanatory diagram showing information necessary for the operation of the second embodiment.

FIG. 28 is a flowchart illustrating an anti-aliasing process according to the second embodiment.

FIG. 29 is a block diagram illustrating a configuration of a driver that performs multi-level driving by power modulation according to the second embodiment.

FIG. 30 shows a pixel clock and edge sub-pixel information aa.
6 is a timing chart showing a relationship between the delay pixel clock and the delay pixel clock.

FIG. 31 is an explanatory diagram illustrating a specific operation example of the second embodiment.

FIG. 32 is an explanatory diagram showing information necessary for the operation of the third embodiment.

FIG. 33 is a flowchart illustrating an anti-aliasing process according to the third embodiment.

FIG. 34 is a block diagram showing multi-level driving by power modulation of the graphic output device according to the third embodiment.

FIG. 35 shows the laser diode on / o shown in FIG. 34;
FIG. 3 is a circuit diagram illustrating details of an ff circuit and a constant current circuit.

FIG. 36 is a timing chart showing a relationship between power control based on a Q output of a D flip-flop and a pixel clock.

FIG. 37 is an explanatory diagram showing a relationship between a control voltage and a laser diode current.

FIG. 38: pixel clock, edge sub-pixel information aa
6 is a timing chart showing a relationship between the delay pixel clock and the delay pixel clock.

FIG. 39 is a circuit diagram showing a configuration of a D / A converter.

FIG. 40 is a timing chart showing a relationship between a beam power and a pixel clock.

FIG. 41 is a timing chart showing the relationship between the power control and the output of the integration circuit.

FIG. 42 is an explanatory diagram showing an operation and a configuration of a tilt information generation LUT.

FIG. 43 is an explanatory diagram showing a configuration of an integration circuit.

FIG. 44 is an explanatory diagram showing a specific operation example of the third embodiment.

FIG. 45 is a schematic configuration diagram of a graphic output device according to a fourth embodiment.

FIG. 46 is an explanatory diagram visually illustrating an example of a basic pattern stored in a comparison circuit in advance, and a process performed when a bit pattern and a basic pattern match.

FIG. 47 is an explanatory diagram visually illustrating an example of a basic pattern stored in a comparison circuit in advance and a process performed when a bit pattern and a basic pattern match.

FIG. 48 shows pulse position modulation used in the fourth embodiment, and
FIG. 4 is an explanatory diagram showing beam power modulation for continuously changing a laser beam output.

FIG. 49 is an explanatory diagram showing a configuration of a compensation signal generation circuit.

FIG. 50 is an explanatory diagram showing pixels for which the compensation data is read in an idle state.

FIG. 51 is a timing chart of the compensation signal generation circuit when the processing mode of the target pixel is a beam power modulation process.

FIG. 52 is an explanatory diagram showing an output example of a latent image based on a conventional anti-aliasing process.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 Host computer 110 Laser writing unit 111 Laser diode 112 Photoconductor 200 PDL controller 201 Receiver 202 CPU 203 Internal system bus 204 RAM 205 R
OM 206 page memory 207 transmission device 208 I / O device 300 image reading device 400 image processing device 500 multi-value color laser printer 504 laser diode 505y 505m 505c 505bk driver 550 laser diode on / off circuit 551 D / A converter 552 constant current Circuit 553 Inclination information generation LUT 554 Integrator 560y 560m 560c 560bk Driver 561 Laser diode on / off circuit 562 Delay circuit 563 Constant current circuit 564 Inclination information generation LUT 565 Integrator 570y 570m 570c 570fk Driver 571f Laser 571f Laser 571f / A converter 573 Constant current circuit 574 Slope information generation LUT 575 Integrator 576 Delay Circuit 801 CPU 802 R
OM 803 RAM 804 Character generator 805 I / F 806 Page memory 807 Line buffer 808 Comparison circuit 809 Compensation signal generation circuit 810 Laser drive circuit 811 Imaging process

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Hanyu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Takashi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hiroki Kubozono 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-2-112966 (JP, A) JP-A-3-3 211591 (JP, A) JP-A-62-24297 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09G 5/20 B41J 2/484 G09G 5/377 H04N 1/23 H04N 1/409

Claims (6)

(57) [Claims] 1. A graphic output device for executing an anti-aliasing process for smoothly expressing jaggies (alias) at an edge portion of a vector image, wherein the vector image data is output by continuously changing a laser beam power. Means, position adjustment means for determining the adjustment start position of the beam power, and the adjustment end position (edge position), and the most distant from the image portion among several pixels with an edge on the scan line. Pixel detection means for detecting a pixel, density detection means for determining the pixel density detected by the pixel detection means in the anti-aliasing process, and the laser beam power from the pixel detected by the pixel detection means to the image portion. Control means for continuously changing to a maximum value; A graphic output device comprising: 2. A graphic output device for executing an anti-aliasing process for smoothly expressing jaggies (alias) at an edge portion of a vector image, wherein the vector image data is output by continuously changing a laser beam power. Means, position adjustment means for determining the adjustment start position of the beam power, and the adjustment end position (edge position), and the most distant from the image portion among several pixels with an edge on the scan line. Pixel detection means for detecting pixels, density detection means for determining the pixel density detected by the pixel detection means in the anti-aliasing processing, and whether the edge to be processed is a right edge or a left edge When the determination unit determines that the right edge, Using the pixel density as power at the end of power modulation, performing power modulation processing using the image output unit, and when the determination unit determines the left edge, the pixel density as power at the start of power modulation, Control means for executing a power modulation process using the image output means. 3. A graphic output device for executing anti-aliasing processing for smoothly expressing jaggies (alias) at an edge portion of a vector image, wherein said vector image data is output by continuously changing a laser beam power. Means for determining an adjustment start position and an adjustment end position (edge position) of the beam power in units smaller than a pixel unit; and wherein the edge to be processed is a right edge or a left edge When the determination means determines whether or not the right edge, from the adjustment start position to the adjustment end position, using the image output means, to change the power from the minimum value to the maximum value, When the determination means determines that the image output hand is the left edge, the image output hand is moved from the adjustment start position to the adjustment end position. Control means for changing power from a maximum value to a minimum value using a stage. 4. A graphic output device for executing an anti-aliasing process for smoothly expressing jaggies (alias) at an edge portion of a vector image, wherein the vector image data is output by continuously changing a laser beam power. Means, density detection means for detecting a pixel density immediately before and immediately after an edge portion of the vector image, and a position for determining an adjustment start position and an adjustment end position (edge position) of the beam power in units smaller than a pixel unit. Determining means, and control means for continuously changing the beam power of the image output means from the density immediately before the edge portion detected by the density detecting means to the density immediately after the edge power adjustment range obtained by the position determining means. A graphic output device comprising: 5. Compensation data is generated for image data of a bit pattern image by comparing the bit map with a predetermined pattern stored in advance, and the image data and the compensation data are combined and output. in graphic output device that performs image quality improvement of an output image by, based on said compensation data, the laser beam power of the portion to be compensated in the image data, smaller than the predetermined dot diameter de
And a beam power modulation processing means for continuously modulating and outputting the laser beam so as to form a laser beam . 6. The graphic output according to claim 5, wherein the compensation data comprises modulation start position information or modulation stop position information of the laser beam and information indicating up to which pixel the beam power is to be modulated. apparatus.