JPH04161987A - Graphic processing device - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphic processing device that removes jaggedness from the image outline of an output image and outputs the image. The present invention relates to a graphic processing device capable of processing data and compatible with binary output media.

[Conventional technology]

In the field of computer graphics, when displaying an image on a CRT, which is an output medium, a technique called anti-aliasing processing is used to make the displayed image more beautiful. This process creates a step-like jagged part (called an alias) as shown in Figure 15(a).
Figure 15(b) visually displays the displayed image by applying brightness modulation to
It is used to smooth the surface as shown in the figure.

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

However, the resolution of the laser printers used in these systems is at most 240dpi to 400dp.
There are many i, computer graphics CR
Similar to the T display, there is a problem in that aliasing occurs due to the low resolution. For this reason, antialiasing processing is now being applied to printing using a laser printer in order to improve the quality of the printed image.

[Problem to be solved by the invention]

However, according to a graphic processing device that applies an anti-aliasing processing method, although it is possible to smoothly express a step-like jagged part by anti-aliasing processing, one pixel is divided into multiple sub-vixels (for example, 49 sub-vixels). Since the area ratio is calculated by counting the number of sub-vixels to be filled in, there is a problem in that it takes time to calculate the area ratio, which hinders improvement in display speed or printing speed.

In addition, in conventional anti-aliasing processing methods, brightness modulation (or density modulation) is performed to express the brightness (or density) with multi-value gradation, so that the jagged parts on the stairs can be smoothed out. There is a problem in that the effect of anti-aliasing processing cannot be achieved without the 8-power medium.

The present invention has been made in view of the above, and an object of the present invention is to smooth step-like jagged portions at high speed.

In addition, the present invention smoothes step-like jagged portions,
Moreover, the object is to be able to output on a binary output medium.

[Means to solve the problem]

In order to achieve the above object, the present invention smoothes the step-like jagged part (alias) of the image outline of an image developed from a hector image or an image input through a reading device, and then is printed or displayed. The graphic processing device includes a detection means for detecting the degree of step-like change in the image contour, and a dot is added at a predetermined position of the step-like jagged part according to the degree of step-like change detected by the detection means, and a dot is added to a predetermined position of the step-like jagged part to visually The present invention provides a graphic processing device equipped with a smoothing processing means for smoothing the image.

(Function) In the graphic processing device of the present invention, the smoothing processing means adds dots to predetermined positions of the step-like jagged portion according to the degree of step-like change detected by the detection means, thereby visually smoothing the step-like jagged portion. express.

〔Example〕

Hereinafter, the graphic processing apparatus of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a block diagram of an image forming system to which a graphic processing apparatus of the present invention is applied.

The image forming system includes a host computer 100 that creates a document written in PDL language (Bost script language is used in this embodiment);
The printer is comprised of a PDL controller (graphic processing device of the present invention) 200 that develops the PDL language sent page by page from the computer into an image, and a binary printer 300 that prints the image output from the PDL controller 200.

FIG. 2 shows the configuration of the PDL controller 200, which includes a receiving device 201 that receives PDL language sent from the host computer 100, and a receiving device 201 that controls storage of the PDL language received and executes smoothing processing. C.P.
PD transferred from the receiving device 201 via U202, internal system path 203, and internal system hash 203
A RAM 204 that stores L language, a ROM 205 that stores programs for smoothing processing, etc., a page memory 206 that stores binary image data that has been subjected to smoothing processing, and binary image data stored in the page memory 206. and a transmitting device 207 that transmits the data to the binary printer 300.

Here, the CPU 202 receives the P received by the receiving device 201.
The DL language is stored in the RAM 204 via the internal system bus 203 according to the program stored in the ROM 205. Thereafter, the graphic elements in the RAM 204 are developed as binary image data on the page memory 206 based on a flowchart to be described later, and then the developed image data is subjected to a smoothing process.

The data in the page memory 206 is then transferred to the transmitter 2
07 to the binary printer 300.

The operation of the above configuration will be explained.

FIG. 3 shows the flow of processing in the PDL controller 200. Since the present invention targets dot images, the details will be omitted, but PDL language (vector data)
When input, first, it is developed as a dot image on the page memory 206 (S301, 5302, 303).
.

Next, the processing direction for one image is divided into the main scanning direction and the sub-scanning direction, and smoothing processing is performed for each scanning line in each case (S304.5305). The details will be explained later, but
The processing itself at this time is the same in both scanning directions. By performing processing separately in both scanning directions, smoothing processing using dot position modulation can be applied to any figure.

As shown in FIG. 4(a), in the main scanning direction processing, the step-like change portion with an almost horizontal inclination is smoothed, and as shown in FIG. The nearly vertical step-like change portion is smoothed, and finally, as shown in FIG. 4(C), an image smoothed in both scanning directions is obtained.

The smoothing process in the -scanning direction will be described with reference to the flowchart in FIG.

The smoothing process includes reading pixel data from the page memory 206 to a predetermined buffer memory (5501), determining and registering the start point and end point (5502), determining and determining the processing target area (5503), and dot punching process (55).
04) is divided into four parts.

First, in step 5501, each pixel data of the scanning line to be processed and the scanning lines above and below it is read from the page memory 206 into a buffer memory for three lines.

Next, for each scanning line read into the buffer memory in step 5502, it is determined for each dot whether that dot is the start point or end point of a straight line segment with a length of two or more dots. , those coordinate values are registered as a pair for each scanning line.

Next, using the start point and end point information registered in the above operation, set the start and end points of each line segment on the scanning line that is currently being processed, and the start and end points of each line segment on the scanning line above and below it. The degree of change on the staircase in the contour of the graphic image is detected and determined from the positional relationship of each of the above, and the portion to be processed is determined.

Thereafter, in step 5504, a dot punching process is performed on the stepped portion to be processed to obtain a visual smoothing effect.

In the following, each of the processes 5501 to 5504 shown in FIG. A detailed explanation will be given in the order of the random punching process.

■Reading pixel data into buffer memory First,
In order to perform processing in the main scanning direction, the pixel data developed in the page memory 206 is stored in a separately prepared buffer memory for three lines. Here, the size of the image is χMAXXYMAX (XMAX<YMA
X) and the array corresponding to the page memory 206 is o
rg [YMAX] [XMAX], buff the array corresponding to the buffer memory 131 [XMAX],
It is defined as Also, the coordinates of each pixel are (i, j) (however,
1-0~XMAX-1. j= O to YM8X-).

With reference to FIG. 6(a), reading of pixel data from the page memory 206 to the buffer memory in the case of processing in the main scanning direction will be described. As shown in the diagram (, buff [1] [i
l contains each pixel data on scanning line j to be processed, buff [0] [il and buff [2]
[il has its upper and lower scan lines (i.e., jl, j÷
1) Each pixel data above is entered.

Therefore, reading pixel data from the page memory 206 to the buffer memory can be expressed by the following substitution formula.

However, this substitution formula is for the first reading, and from the second time onward, the following formula is used.

In the case of reading in the main scanning direction, the buffer memory is not used for (YMAX-XMAX) dots x 3 lines, but it is assumed that the value of that portion is initialized to 0.

Similarly, regarding reading into the sofa memory in the case of processing in the sub-scanning direction, as shown in Figure 6(b), start point/end point determination and registration processing Generally speaking, a raster image has several functions at the scanning line level. This is a set of straight line segments created by pixels, and each of these segments has a correlation with the upper and lower scanning lines to form an image.

In the present invention, in order to define a straight line segment on a scanning line, it is determined whether all pixels on each scanning line are the starting point or the ending point of the line segment, and those corresponding to each are registered. do. This algorithm is shown in the flowchart of FIG.

First, on each scanning line, the dot value is other than O (b
Find uff [jl fil≠0) (570
1), the value of one of the dots on either the left or right side of the dot is other than 0 (buff [jl [i-1]≠0. or,
buff [jl li+1]≠0), the dot is set as the starting point and ending point. However, if the dots on both sides have values other than O, or if they are a single point, they are excluded from the determination (5704, 5705, 5706).

If the value of the dot on the right is other than 0, and the value of the dot on the left is O, the X coordinate value i of the dot in question
is assigned to the array 5trx[jl[k], and j
It is registered as the starting point above (5707).

Also, if the value of the dot on the left is other than O, and the value of the dot on the right is O, the X coordinate value i of the dot in question is assigned to the array endx[jl[k]. , is registered as the th end point on the scanning line (5708).

Here, the range of k is from 1 to PMAX at maximum (in this embodiment, PM8 = 1000).

As an exception to the start/end point determination, there are cases where the X coordinate value of the dot of interest is 0 (left edge of the image) or XMAX (right edge of the image), but in the former case, even if the value of the dot to the right is other than 0 Please register as a starting point (5702.5707)
In the latter case, if the dot value on the left is other than 0, it is registered as the end point (5703, 5707). These judgments and registration processes are performed for all dots stored in the buffer memory (5709 to 5707). 5712). FIG. 8 shows an example of the above processing.

(2) Discrimination and determination process of processing target portion A stepped change portion in an arbitrary graphic image contour portion can be defined as a portion where straight line segments on each scanning line overlap vertically.

In other words, if there is a starting point or ending point of any line segment on either the upper or lower scanning line between the starting point and ending point of a certain line segment, those line segments can be considered to overlap, and therefore Step-like changes can be detected.

In the present invention, various conditions are added to this detection method to determine whether or not to perform smoothing processing, which will be described later, and to determine the range to be processed.

As described above, the step-like change portion is detected based on the vertical positional relationship between the start and end points of each line segment on each scanning line, and the pattern is basically as shown in FIG. 9(a).

It can be roughly divided into four types shown in (b), (C), and (d). Here, in figure (a), the starting point of the line segment of interest is between the starting point and end point of the line segment below, and in figure (b), the end point of the line segment of interest is between the starting point and ending point of the line segment below. In that case, in the same figure (C), the starting point of the line segment of interest is between the starting point and end point of the upper line segment, and in the same figure (d), the end point of the noticed line segment is between the starting point and ending point of the upper line segment. In each of the cases (a) to (d) in the figure, the processing target range is the shaded area.

Determination of the processing target range will be explained with reference to FIG.

Two variables, grad and stx, are used to determine the processing target range. Here, grad indicates the number of dots within the processing target range on an arbitrary scanning line, in other words, it indicates the slope of the stepwise change. In the case of Figure 10,
grad=s trx [j l [kl −s tr
Represented by x [j+1] [kl. In addition, stx indicates the starting point coordinates of the processing target range, and in this case, 5tx=st
rx[j+1] [kl.

Conditions shown in FIG. 9(a): (strx[jl[k
l>5trx(j+1![4]) && (strx[
jl [kl<endx[j+1] [il)], a step-like portion is detected and a processing target range is determined, but it is not necessarily appropriate to process everything that meets these conditions. That is, since there is a problem that unnecessary parts are processed, it is necessary to add more detailed conditions to these conditions.

Furthermore, the conditions for addition will be explained using an example in which the starting point of the line segment of interest is between the starting point and the ending point of the lower line segment (FIG. 9 (case al)).

Note that when grad <= 3, adding processing will make the jitter more noticeable, so no processing will be performed even though it is determined to be a portion to be processed. Similarly, if grad>200, no processing is performed because it can be regarded as a substantially horizontal line or vertical line.

As an additional condition, as shown in FIG. 11(a), (s
trx[j-1] [hl<=strx[jl [
kl) && (endx[j-1][hl >=
s trx [j] [k]), no processing is performed.

As shown in FIG. 11(b), (endx [jl [
k-1]! =strx[N [kl] && (en
dx[j-II fhl>=strx[jl [ki]
In this case, process the shaded part.

As shown in FIG. 11(b), (endx [jl [
k-1]! =strx[jl [kl] && (e
ndx[j-1] [hl>=strx[jl [kl
), process the shaded part. In this case, grad・
5trx[N [kl-endx[jl [k-1]-
1, and 5tx=endx[jl [k-1]+1.

As shown in FIG. 11(C), when the starting point of a line segment is located at the four dots in the shaded area, (buff [j-1] [hl
! = 0), no processing is performed.

However, the above h is h=s trx [j] [kl
~s trx [j] [kl +3.

(2) Dot punching process The dot punching process is a process in which dots are randomly punched (added) at predetermined positions in the processing target range (stepped jagged portion). In other words, it is a jagged smoothing process using dot position modulation, and is based on the principle that a visual smoothing effect is obtained by punching out dots in the step-like part of the contour of the figure image and adding a high frequency component. There is. There are various patterns for punching out dots, and the effects achieved by each pattern are different, but in this embodiment, the punching pattern that is most effective among them is used. below,
The punch pattern will be explained with reference to FIGS. 12(a) and 12(b).

FIG. 12(a) shows a case where the starting point of the line segment of interest is between the starting point and ending point of either the upper or lower line segment, and as shown in the figure (the range to be processed is a flat area where no dots are placed, It is divided into a treated part on which a certain number of dots are applied.Here, the length of the flat part nc is nc=dnp+2, where dnp=
Define in t (grad/2). This differs depending on whether the length grad of the processing target range is an even number or an odd number. In addition, in the part to be processed, all dots 2n points in front of the edge dot are struck. Here n=1.2,3
．． . . . nmax, and nmax is obtained by the following formula.

nmax=int [(grad/2-nc)] In other words, in the processed part, "dots are struck" from the nmax number of dots before the edge dot to the dot one before the edge dot. Repeat the "No" operation alternately.

Furthermore, in addition to this, the dot after the edge dot (indicated by the dotted line in the figure) is removed to complete the process.

This pattern is applied when the end point of the line segment of interest is between the start and end points of either the upper or lower line segment, as shown in Figure 12 (
Shown in b). In this case, since the order of the flat part and the to-be-processed part within the processing target range is reversed, the processing order is also reversed. That is, first, the dot in front of the edge dot (indicated by the dotted line in the figure) is removed, and then from the dot one place after the edge dot to the nmax number of dots after the edge dot, "dot not be struck". The process is completed by repeating the operation of hitting the dots alternately.

In addition, the operation of hitting/not hitting (dotting) dots is done directly.
Array org[jl[i] corresponding to page memory 206
The value of 0. Alternatively, this can be realized by rewriting the dot value to the maximum value (255 in the program described later).

Further, although the explanation is omitted, a flowchart of the aforementioned dot punching process is shown in FIG. 13(a).

FIGS. 13(b) and (C) show variables in the flowchart. In the case of 5W=O, the target processing range is the image outline at the starting point, and in the case of SW・1, the target processing range indicates that is the image contour of the end point.

An embodiment of the smoothing process described in the above processes 1 to 2 will be described with reference to FIGS. 14(a), 14(b), and 14(C).

Figure 14(a) is the original image (300 dpi, 32
14('b) shows the result of smoothing processing in the main scanning direction. Furthermore, the image of FIG. 14(b) is subjected to smoothing processing in the sub-scanning direction, and the result is shown in FIG. 14(c).

As is clear from comparing Figure (a) and Figure (C),
Smoothing of stepped jagged parts has been achieved.

Further, in this embodiment, as described above, since subpixel division and subpixel filling processing are not required, smoothing processing can be performed at high speed. Furthermore, the first
Since the processed image in FIG. 4(C) is expressed in binary, it can be output as is by the binary printer 300.

〔Effect of the invention〕

As described above, the graphic processing device of the present invention can process an image image developed from a hector image, or a graphic processing device of the present invention.

In a graphic processing device that smooths and prints or displays a step-like jagged part (alias) of an image outline of an image input via a reading device, a detection means detects the degree of step-like change in the image outline; The step-like jagged part can be smoothed by adding dots at predetermined positions of the step-like jagged part to visually smooth it according to the degree of the step-like change detected by the detection means. can be done quickly.

Furthermore, it is possible to smooth the step-like jagged portion and output it on a binary output medium.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an image forming system using the graphic processing apparatus of the present invention, FIG. 2 is an explanatory diagram showing the configuration of a PDL controller, FIG. 3 is a flowchart of processing in the PDL controller, and FIG. 4(a) . (b) and (C) are explanatory diagrams showing the processing order of smoothing processing, the flowchart of smoothing processing in Fig. 5, and Fig. 6 (a).
. (b) is an explanatory diagram showing the loading of pixel data into the buffer memory, FIG. 7 is a flowchart for determining and registering the starting point and ending point, FIG. Figure 9 (a), (b). (C) and (d) are explanatory diagrams showing the pattern of the vertical positional relationship of the start and end points of each line segment on each scanning line for the step-like change part, Fig. 10 is an explanatory diagram showing the processing target range, and Fig. 9 ( a)
, (b), (C) are explanatory diagrams showing additional conditions, 12th
Figures (a) and (b) are explanatory diagrams showing random patterns,
FIG. 13(a) is a flowchart of the dot punching process, FIGS. 13(b) and 13(C) are explanatory diagrams showing variables in the flowchart of FIG. 13(a), and FIGS. 14(a), (
b), (c) are explanatory diagrams showing processing results according to the example,
FIGS. 15(a) and 15(b) are explanatory diagrams showing conventional antialiasing processing. Explanation of codes 100・-11--Host computer 200----
PDL controller 201--receiving device 202-
・-----CP U203----Internal system lot 204---RAM 205・---ROM20
6--------Bage memory 207---m-Transmitting device 300--Binary printer

Claims (1)

[Scope of Claims] A graphic processing device that smoothes and prints or displays a step-like jagged portion (alias) of an image contour of an image developed from a vector image or an image input via a reading device, a detection means for detecting the degree of step-like change in the image contour; and a dot added to a predetermined position of the step-like jagged portion according to the degree of step-like change detected by the detection means, so as to visually smooth the image. A graphic processing device characterized by comprising: smoothing processing means for smoothing.