JP2577276B2 - Line break detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention is based on binary image data of an image (hereinafter, referred to as an "article image") including an underprint character, an illustration, a logo, a graphic, and the like created on a mount, and cuts off a line of the underimage. And a method for detecting a part.

[Prior art]

In a plate making process for making a printing plate for color printing, an underlaying board that is an original of characters and line drawings is created. The underlaying board has the same size as the final printed matter, with the typesetting and manufactured ruled lines.
They are arranged with the same quality. Instructions for the subsequent steps are also written on the underlaying sheet, and also serve as instructions for the plate making process. In many cases, a process for filling a part of the area in an image with a desired uniform color (flat screen refining) is performed in the plate making process. In recent image processing systems, flat screen binding, which has been performed manually until now, is automatically performed. In such a system, binary image data of a composition image is read by an image reading device, and a desired closed area in the composition image is filled with a desired color by an image processing device, thereby performing a flat-screening. I have. When such a “painting process in a closed area” is performed, a line drawing that should originally form a closed area in the composition image may have “line breakage”. The cause of the “line break” is a line break existing on the original image (underlaying board), a reading error when reading by the image reading device, and the like. Conventionally, the operator has directly searched for the position of a broken line portion from the composition image displayed on the CRT, and has corrected the composition image so as to connect the broken lines.

[Problems to be solved by the invention]

However, since the width of line breaks is often from one pixel to several pixels, it is difficult for the operator to find them on the CRT, and when there are many line breaks, they are all found. There is a problem that it takes a considerable processing time to correct the error. As a method of finding a broken line in an image, for example,
Japanese Patent Application Laid-Open No. 61-139892 discloses a technique using a vectorization technique of a binary image. An image processing apparatus for processing a line image (hereinafter, referred to as a "line image processing apparatus") performs relatively simple image processing in which the level of binary image data is switched for each pixel. Is a relatively complicated process, and its processing device is also complicated and relatively expensive. Therefore, when the function of vector data processing is added to the line drawing processing device, there is a problem that the cost of the line drawing processing device is greatly increased. In addition, since line breaks cannot always be detected 100% by a method using vectorization technology, the operator often checks whether or not there is a line break, and the overall processing time is not necessarily shortened. There were also problems. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem in the related art, and provides a line break detection method capable of easily finding a line break in an image without using a complicated vectorization technique. The purpose is to do.

[Means for Solving the Problems]

In order to solve the above-mentioned problem, a line break detecting method according to claim 1 includes: (a) a step of specifying a processing target area in a line drawing image displayed on a display means; and (b) the processing target area. Is divided into a plurality of divided regions, and (c) for each of the plurality of divided regions, an independent region portion separated by a boundary line of a different pixel value based on a pixel value assigned to each pixel. Recognizing and assigning different colors to the mutually independent areas,
(D) displaying the image of the processing target area on the display means while separately painting each area portion with the assigned color; and (d) a line drawing part of the image displayed in the step (c), which is different in color. Displaying the displayed portion to detect a line break existing in the line drawing portion. In the step (c), the processing target area is divided into pixel blocks each having a predetermined shape composed of a plurality of pixels, and a priority of a color of a pixel to be extracted as a representative pixel in each pixel block is determined in advance. Preferably, the method further includes a step of extracting a representative pixel from each pixel block according to the priority, generating a reduced image represented as a set of the extracted representative pixels, and displaying the reduced image on a display unit. Further, in the step (a), different colors are assigned to mutually independent region portions in the line drawing image, and the line drawing image is displayed on the display means while each of the region portions is painted with the assigned color, thereby forming a closed region. Comparing the internal color and the external color of the line drawing element to be processed, and designating the processing target area so as to include the line drawing element having the same internal color and external color. Here, the term “line drawing” generally means an image drawn with lines and planes of uniform density, and is a term that includes not only images such as figures but also character images.

[Action]

If an image in which different colors are assigned to mutually independent area portions is displayed, the line drawing portion where the line break exists is displayed in different colors before and after the line break. Therefore, a line break can be easily detected only by finding a line drawing portion having a different color. When displaying the processing target area in different colors,
Often displayed as reduced images. As a method of extracting representative pixels in a pixel block in order to generate a reduced image, priorities of colors are determined in advance, and the representative pixels of each pixel block are extracted according to the priorities. It is represented as a relatively thick line drawing on the reduced image. Accordingly, it is possible to easily recognize a change in the color of the line drawing portion, and it is possible to more easily detect a broken line portion. In addition, before specifying the processing target area, when the independent area portion of the entire line drawing image is displayed in a different color and displayed, the color of the inside of the line drawing element which should form the closed area is the same as the external color. If there is, it is understood that there is a line break somewhere in the line drawing element. Therefore, if the processing target area is specified so as to include the line drawing element, only the area including the line break can be specified as the processing target, and the line break detection processing can be performed efficiently.

【Example】

A. Configuration of Apparatus FIG. 1 is a diagram showing the application of an embodiment of the present invention.
Block diagram showing a schematic configuration of an image processing apparatus for performing a part detection process.
FIG. This image processing apparatus requires the following components.
Element. (A) Image input device 1: Reads the composition image, and its binary
This is a device that obtains images, and is composed of a flat type scanner, etc.
You. (B) Run-length compression unit 2: read by image input device 1
Run length compression of the binary image data
Create run-length data. (C) Image memories 31, 32: run-length compression unit 2 and
Run-length data of the composition image given by the CPU 6
Memory for storing data. The first image memory 31 stores the composition image
The run-length data of the
Record the run-length data of the composition image with the cut part corrected.
Remember The second image memory 32 is used when detecting a line break.
And temporarily used memory.
Stores the image area data specified by the operator
I do. (D) Run-length extension unit 4: provided from image memories 31 and 32
Run-length data into bitmap data
I do. (E) Color monitor section 5: run-length compression section 2 and CPU section
6 for displaying the image data provided from
And includes the following components: Display memory 51: Record bitmap data of the image to be displayed.
Memory to remember. Color palette 52: Image data provided from the display memory 51
The color number (described later) included in the data
), G (green) and B (blue) density signals
You. Color numbers are specified for each image area of the composition image.
I have. Color monitor 53: Displays a color image. Display control unit 54: Control of image display on the color monitor 53
I will do it. The color information stored in the color palette 52
(Information indicating the correspondence between the color number and the density signal of each of the three primary colors)
Change the display cursor on the color monitor 53
Control the position to correspond to the mouse movement. (F) CPU unit 6: Control of the entire image processing apparatus and necessary functions
This is a device for performing a calculation, and has the following components. Control operation unit 61: control of each unit of the image processing apparatus, and
Extraction, division, area separation, special low density
Performs calculations such as grading processing. Auxiliary memory 62: temporary memory required for various processes
Memory for storing information. Mouse 63: processing on image displayed on color monitor 53
It is used when specifying an elephant area or the like. (G) Image output device 7: Fills the image with the broken line
Recorded on a storage medium such as a system. B. Procedure of processing Fig. 21 shows the procedure of line break detection processing and connection processing.
It is a flowchart shown. In step S1, first place characters and figures on the mount
Prepare the composition. Fig. 3 is a plan view showing an example of a composition BC.
is there. This composition BC is a square and a circle on a white mount BS.
Are placed at the bottom of these figures, such as A, B, C, etc.
Characters are placed. These figures and characters are drawn in black
Has been. In step S2, the binary image data Db of the composition BC is input to the image.
Read with force device 1. This binary image data Db
This is data indicating whether each pixel in the image is black or white. In step S3, the binary image data Db is stored in the image input device 1
Is sent to the run-length compression unit 2 where the run-length
It is converted to gus data Dr. FIGS. 4A and 4B show the structure of the run-length data Dr.
It is explanatory drawing for showing. Fig. 4A shows only the character A in the composition image.
Is shown. In the figure, the vertical direction is the main scanning direction Y,
It is assumed that the horizontal direction is the sub-scanning direction X. Also on the mount
Is assumed to be between 0 and 150 in the main scanning direction Y.
I have decided. FIG. 4B shows the sub-scanning coordinates xi for this composition image.
3 shows the configuration of run-length data Dri. run
The length data Dri is composed of four continuous data DDi1 to DDi.
4 (hereinafter referred to as “unit run length data”)
It is configured. Each unit run length data DDi1 to DDi4
Consists of 32 bits each, with the most significant 1 bit
Is a black and white finger indicating whether the unit run-length data is black or white.
This is the constant data Dwb, and the next 15 bits are the system
System color data Dsc indicating color number, lower 16 bits
Indicates the main scanning coordinate of the start point of the unit run length.
The target data is Drc. As shown in FIG. 4A, in the sub-scanning coordinates xi, the main-scanning coordinates
The section where Y is from 0 to 99 is white, the section from 100 to 119
Is black, and the section from 120 to 150 is white. Three simple
The run length data DDi1 to DDi3 are the above three sections
The main scanning coordinates of the starting point of the
doing. The fourth unit run length data DDi4
The value of the main scanning coordinates is the maximum value (= 150).
That the run-length data for the main scan line has been completed
Is shown. At this point, the system colors have been determined.
System colors in the run-length data
The data Dsc has a meaningless value. The run length data Dr obtained as described above is
The image data supplied from the run-length compression unit 2 to the first image memory 31
Is stored. Also, based on this run length data Dr,
3 is displayed on the color monitor 53.
However, the image displayed here is a black-and-white image. In step S4, a region separation process is performed on the entire composition image.
Is performed. Area separation processing is the process of dividing the black and white areas.
Distinct areas separated from each other by a boundary line
And a different number (system color number) for each distinguished area
It refers to the process of assigning Ns. In the example of FIG.
The black part of the shape, the circular black part, and the black of characters such as A, B, C
Color part and white part around rectangular or circular figure (base of mount
Area), each white part inside each figure, and inside each character
Are divided into white areas. The number assigned to each separation area is the system color
The number is used when this number is automatically calculated by the control operation unit 61.
Number, which is also used as a color number.
Because you can. Note that the details of the region separation processing are further described below.
It will be described later. The image after the area separation processing is displayed on the color monitor 53.
You. At this time, each system color number Ns is stored in the color palette 52.
Convert to different colors and display each separation area with different colors
I do. For example, if there is no broken line in the circle C,
The inside and outside are displayed in different colors. However, the figure
If there is a broken line in the circle C, the inside and outside are the same area.
Area, so they are displayed in the same color. Therefore, the operating
Observe the color image displayed on the color monitor 53
And the color of the inner area is the same as the color of the outer area
Easily find figures with broken lines by searching for figures
Can be found. In step S5, the operator turns on the color monitor 53.
As a result of observation, a broken line was found somewhere (for example,
), The processing after step S6 is performed.
The detection of the position of the line break and the joining process are performed.
Be done. First, in step S6, the operator detects a line break.
A region where processing is performed (hereinafter, referred to as a “processing target region”)
Specify the PR on the composition image, and save the image data
Is stored in the second image memory 32. As shown in FIG. 5A, the processing target region PR is a rectangular region.
And the main scanning direction X from each of the two vertices P1 and P2
Have sides drawn in parallel with the sub-scanning direction Y
You. In the composition image displayed on the color monitor 53,
The perlator uses the mouse 63 to determine the positions of the two vertices P1 and P2.
If specified, the image data of the image in the
The second image memory 32 extracted from the first image memory 31
Is stored. The first image memory 31 stores the original
The image data of the composition image is stored as it is. 5A
In the figure, the extracted image of the processing target region PR is enlarged.
I have. In step S6, a line drawing to be processed by the operator is further performed.
Specify the display color number Nd of the element (circle figure C in Fig. 5A)
You. The display color number Nd is used to display an image on the color monitor 53.
This is a number indicating the color when the
It is a number given independently. In the composition image, black and white
Is a display color. For example, specify the display color of circle C
When displaying, a number indicating black as the display color number Nd (for example,
If 5) is specified. The display color can be specified, for example, by
Display on the color monitor 53 and use the mouse 63
This is performed by selecting one color from a large number of display colors. The next steps S7 to S9 are automatically performed by the control operation unit 61.
This is a line cutting process in the circle C in the processing target area PR.
This is a process for displaying the display portion in an easily viewable manner. In step S7, the processing target region PR is
Divided equally. FIG. 5A shows the boundary line BL for division,
2 shows two divided processing regions PR1 and PR2. Processing object
The coordinates of the vertices P1 and P2 of the region PR are (X1, Y1), (X2, Y
Assuming 2), the division boundary line BL is expressed by the following equation. X = (X1 + X2) / 2 The reason for dividing the processing target region PR in this way is as follows.
It will be described later. In step S8, that of the two divided processing regions PR1 and PR2
For each of them, the same region separation processing as described above is performed.
You. FIG. 5B shows the region R1 separated by the process of this step.
To R6. Each separation area R1 to R6 has a system color
Numbers Ns are sequentially assigned, for example, from 1 to 6. If there is no line break in the circle C, each divided processing area PR1,
Each line drawing part of the circle C of PR2 has one separation area.
Are divided and assigned one system color number Ns
It is. However, as shown in FIG.
Has two line breaks CP1 and CP2, so each divided processing area P
In R1 and PR2, there are two line drawing parts of circle C
Are separated into separation regions R2, R3 and R5, R6, respectively.
Different system color numbers Ns are assigned to these separation areas.
You. System color number Ns assigned to each separation area R1 to R6
Is the system color data Dsc in the run length data Dr.
(See Figure 4B). And that run-length
The scan data Dr is stored in the second image memory 32. At this time, as shown in FIG. 6, each system color number Ns and
The system color table SCT indicating the correspondence with the display color number Nd
Created. Line drawing section in system color table SCT
Display of line drawing in separation areas R2, R3, R5, R6 corresponding to minutes
The display color number Nd = 5 indicating the color (black) is registered, and the
Display color (white) in the separation areas R1 and R4 corresponding to the base
Is registered as a display color number Nd = 1. Note that dividing the processing target region PR into two is due to line breaks.
Even if there is only one part, its position can be easily detected.
This is so that you can get out. Divide processing target area PR
Assuming that segmentation processing is performed without
C has only one line break (for example, only CP1)
In this case, the whole circle C is regarded as one separation area.
Is displayed in one system color.
Is difficult to find on the color monitor 53. one
On the other hand, as described above, the processing target region PR is divided into two.
In other words, the circle graphic C is divided into two at the division boundary line BL.
Therefore, even if there is only one line break,
The subsequent line drawing parts are distinguished as different areas,
Will be displayed in different colors. Note that the broken line is
The countermeasures when the vehicle is on the boundary line BL will be described later. In step S9, the image of the processing target region PR (FIG. 5B)
Reduce the density. Low density generally refers to monitors and the like.
Reduce the number of pixels in the image to display the image
The process of obtaining a reduced image.
It is a kind of degree. In this embodiment, the thinning process is executed.
Shall be performed. That is, for example, a 2x2 pixel block
The pixels are decimated into one pixel. At this time, 2x2
A pixel at a predetermined position in the pixel block (for example, an upper left pixel)
Display color number Nd and system color number Ns
Adopted as the primary display color number Nd and system color number Ns
You. The image data (run-level
Data) from the control operation unit 61 to the second image memory.
Given to 32 and stored. The image data of which density has been reduced is transmitted to the color monitor unit 5.
And the reduced image (No.
5C) is displayed on the color monitor 53. On this occasion,
Each color palette 52 is separated according to the system color number Ns
Areas R1 to R6 are painted in different colors from each other,
The displayed image is displayed on the color monitor 53. In step S10, the operator
The image (Fig. 5C) is visually inspected, and the dividing boundary line BL and the line
A line other than the intersection with the image (circle C)
Detects CP1 and CP2 where the color of the image has changed (line breaks)
I do. If there are no line breaks, each divided processing area PR1, PR2
Does not change the color of the line drawing portion of the circle C,
As above, just look for the part where the color is changing
Line breaks CP1 and CP2 of type C can be found. In the low-density image, the gap between the line breaks CP1 and CP2
Often, you can't see the minute, but the color
If there is a change in the
You can see. In step S11, the operator removes line breaks CP1 and CP2.
The surrounding areas SR1 and SR2 are designated on the color monitor 53. This
Is specified using the mouse 63, two regions SR1 and SR2
Specifying the positions of vertices Q1, Q2 and Q3, Q4 respectively
This is done. The designated areas SR1 and SR2 are shown in FIG.
Is displayed on the color monitor 53 in an enlarged manner as shown in FIG. this
In this case, as shown in FIG.
The colors of the separation areas R2 and R3 to be
(In this case, black). In step S12, the operator displays the enlarged area S
A process of connecting the line break CP1 is performed while watching R1. This
In the connection process, the operator is separated at the line break CP1.
In the two regions R2 and R3, the points PP1 and PP2 are
Mouse 63, and these two specified points PP1 and PP2
By instructing the pixels in between to be connected by line segment SG.
It is done. In other words, this connection processing is performed by two fingers.
Pixels between fixed points PP1 and PP2 are assigned the same display color number Nd (or
Is the process of re-assigning the same system color number Ns).
You. The width of the line segment SG connecting the two specified points PP1 and PP2
It is not necessary that the width of the figure C is substantially the same as that of the figure C.
What is necessary is just the elementary width. This is a line segment that is at least one pixel wide
If the separation areas R2 and R3 are securely connected by SG,
When performing the set processing, the inside of the circle
Can be prevented from being painted in a different color from the outside
It is. When the linking process is performed, the origin O (the
The coordinates of two designated points PP1 and PP2 with respect to (see Fig. 3) are controlled.
It is determined by the calculation unit 61. Further, the control calculation unit 61 includes:
The original image data (LAP) stored in the first image memory 31
Length data) and modify the two designated points PP1 and PP2
Image data representing the composition image so that
Modify the data. The image data corrected in this way is the first
It is stored in the image memory 31. The corrected image data is further processed by the control operation unit 61.
Various types of image processing such as flat-screening are performed. Soshi
From the first image memory 31 in response to an operator's command.
The image data is supplied to the image output device 7 via the run-length extension unit 4.
And recorded on a recording medium such as a film or a printing plate. As shown in FIG. 5C, the dividing boundary line BL and the circular figure
The part where C intersects is always displayed in a different color,
It is determined whether there is a line break near the divisional boundary line BL.
-It is difficult to make a direct determination on the monitor 53. To address this issue, for example,
Several methods are conceivable. The first method is to specify the processing target area PR (see Fig. 3)
After performing the processing of steps S6 to S12 once,
Method of performing similar processing by specifying different processing target areas
It is. The second processing target area is the first processing target area.
What is necessary is just to specify so that an area | region and a position and a size may differ. In the second method, the designation of the processing target region PR is not changed,
The position of the division boundary line BL is not on the left or right in the sub-scanning direction X.
Then, steps S6 to S12 are performed. In this case, processing
There is no need to specify the target area PR. In the third method, as shown in FIG.
By specifying the regions SR3 and SR4 near the intersection with the circular figure C,
This is a method of performing the processing of steps S11 and S12. In this case
Are the lines in the enlarged image of these regions SR3 and SR4.
If you perform the splicing process only when a cut is found,
Good. In the third method, the intersection of the circle graphic C and the division boundary line BL
Two regions SR3 and SR4 near the point and a line break 2
Two areas SR1 and SR2, and expand each area
If you check the position of the line break and connect it,
All line breaks in form C can be detected and corrected. Thus, in the above embodiment, two processing target regions PR
Divided into the processing areas PR1 and PR2,
Region separation processing is performed on the regions PR1 and PR2 to
Each area is displayed in a different color
Therefore, make sure that there is a broken line in the part where the color changes.
There is an advantage that it can be easily found. C. Details of Area Separation Processing The area separation processing is performed as follows, for example. 8th
The figure shows the processing window W used for the area separation processing.
It is. Pixels Pa with diagonal lines are subject to processing
Pixels, and the other pixels Pb to Pe are peripheral pixels of the pixel Pa.
You. This processing window W is sub-scanned along the main scanning direction Y.
Move in order from the smaller direction X. And the picture
When the element Pa is black, for example, black pixels exist in the peripheral pixels Pb to Pe.
If not, assign a new system color number Ns to pixel Pa.
Hit it. On the other hand, any of the peripheral pixels Pb to Pe are black pixels
Is already assigned to that black peripheral pixel
The system color number Ns used for the pixel Pa
No. Ns. The same applies to the case where the pixel Pa to be processed is white. However
When the pixel Pa is white, the pixels Pc and P
When e is white and the other pixels Pb and Pd are black, the pixel P
Different system color numbers Ns for c, Pe and pixel Pa to be processed
assign. In this way, the white pixels
If they are adjacent only diagonally, these pixels
It is recognized that they form mutually different regions. Like this
If so, black independent areas and white independent areas
Can avoid area separation like crossing
You. In this way, the processing window W is moved,
The process of sequentially assigning different system color numbers Ns to each area
In the same area, two or more system color numbers Ns
May be given. Figures 9A through 9D show this
It is an explanatory view showing a procedure of processing in such a case. First, the composition image is a black area Ra as shown in FIG. 9A.
And three white areas separated from each other by this area Ra
It is assumed that the region is composed of regions Rb, Rc, and Rd. The processing window W is moved in the sub-scanning direction along the main scanning direction Y.
Moving sequentially from the smaller X, as shown in Fig. 9B
As shown, each region Ra to Rd has a different system color number Ns
Are assigned. In FIG. 9B, the number written in each pixel is
The system color number Ns assigned to the pixel is shown. Ma
Pixels for which no numbers are written are still system color numbers.
No. Ns is not assigned. Shown in Figure 9B
As shown in the figure, the black area Ra has the system color number Ns
= 2 assigned pixels and Ns = 4 assigned
Pixel. Processing window W is in the position shown in Fig. 9B
Of the pixel adjacent to the processing target pixel Pa
The value of the system color number Ns of Pa is 2, and the system color number Ns of the pixels Pd and Pe is
The value of the stem color number Ns is 4. In this case, "Ns = 2
Ns = 4 represents the same system color "
Is temporarily stored in the memory 62, and a small
One system color number Ns = 2 is assigned. This is 9A
When applied to all pixels in the figure, the system color image in Figure 9C
(Images painted in system colors) and Fig. 10
One system color table IST is obtained. The same system color table IST has the system color number Ns =
2 and Ns = 4 represent the same system color.
That is, they are assigned to the same image area, and)
Ns = 5 and Ns = 6 also represent the same system color
Is shown. Note that this same system color table IST
Are stored in the auxiliary memory 62. Next, the control calculation unit 61 is stored in the auxiliary memory 62.
Refer to the same system color table IST and
Different system color numbers even though they are
Common system color numbers for assigned pixels
(For example, the smallest system among the same system color numbers
The process of reassigning the color numbers
Do. As a result, as shown in Figure 9D, all regions
Different system color numbers Ns are assigned to areas Ra to Rd one by one.
An assigned image is obtained. Note that the above description has been made with respect to processing on
4A and 4B.
The same processing can be performed on the compressed image data. By performing the above processing, the processing target area in FIG.
Each region R1 to R6 in the region PR is separated from each other, and
Pixels within one area are assigned the same system color number Ns.
Hit. D. Modifications The present invention is not limited to the above embodiment.
In various forms without departing from the gist of the invention.
It is possible to implement, for example, the following modification
Is also possible. In the above embodiment, before designating the processing target area PR,
In steps S4 and S5, area separation processing is performed on the entire composition image.
No, find elements of line art with broken lines
did. However, without performing step S4, the closed region (closed music
Specify the area containing the line drawing that composes the line) one by one,
The processing after step S6 may be performed. However, steps S4 and S5 are performed as in the above embodiment.
Then, only the line drawing with the line break
Detection and connection processing can be performed.
There is an advantage that the entire image can be efficiently processed. In the above embodiment, the processing target region PR is divided into two.
The area separation process was performed by using
It may be divided into a plurality of areas and the area separation processing may be performed.
No. The shape of the processing target area PR and the area SR for displaying the enlarged image
The shape of 1 to SR4 is not limited to a rectangle, and may be any shape. An example
For example, it may be circular, and the operator
By tracing the outline with a mouse etc.
The shape may be arbitrarily specified. Density reduction processing is limited to so-called thinning processing
Even if special low-density processing is used as shown below,
Good. In the thinning process, for example, a 2x2 pixel block is
When replacing pixels, pixels at specific positions in the pixel block
Is selected, and the color of the pixel is set as the color of the pixel after thinning. On the other hand, in the special low-density processing, the priority of the color is determined in advance.
In addition, the priority among the colors of each pixel in the pixel block is
The highest color is selected as the color of the pixel after density reduction. FIG. 11 is a flowchart showing a detailed procedure of the special low-density processing.
It is a chart. In general, MxN pixels
(M and N are integers) are reduced to one pixel. In this example,
It is assumed that M = N = 2. When the special low-density processing is started, first, the variables j and
And the variable i is cleared to 0 (steps 810 and 820). Then, the image at the coordinates (M · i + 1, N · j + 1)
Starting from data D (M · i + 1, N · j + 1), an MxN image
The original image data is read (step 830). (N
In the following, the image data of each pixel is referred to as “pixel data”.
Huh. Here, since M = N = 2, initially (i
= 0, j = 0), pixel data D (1, 1), D (2, 1), D
Read (1,2), D (2,2) and execute this step
, The pixel data D (3,1), D (4,1), D (3,
2), D (4,2) and pixel data are read out in 4-pixel units
You. Subsequently, the pixel data D read in step 830 is
The color code (display color number) is stored in the auxiliary memory 62.
Compare with the contents of stored priority generated code table TBL
Processing is performed (step 840). Priority generation code table
As shown in Fig. 12, the priority of the display color is
It is a recorded table. In this embodiment, step S6
The display color number Nd of the processing target region PR specified in (FIG. 2)
The color (black) corresponding to (= 5) is set to the highest priority
Is done. In the case of a black-and-white image, the superior color of one of black and white
If the priority is set in the priority generation code table TBL
In the case, the other priority is stored in the priority generation code table TBL.
It does not have to be set. Indicates the same color as the four pixel data D in the pixel block
Color code is found in the priority generation code table TBL.
If specified, the color code that represents the same color
A priority color code is selected (step 850). one
In step 840, a color code indicating the same color has priority.
If it is determined that it is not in the
From the pixel data D read in step 830
Select the pixel data D (M · i + 1, N · j + 1)
Step 560). In the example of pixel data shown in FIG. 13, the pixel data D (1,
Image showing color 2 from 1), D (2,1), D (1,2), D (2,2)
The raw data D (2,2) is selected and the pixel data D
Indicates color 1 from (3,1), D (4,1), D (3,2), D (4,2)
The pixel data D (2,2) is selected. Subsequently, the selected pixel data D is stored in the representative pixel data.
Output to the display (color monitor 53)
(Step 870). Subsequently, the variable i is incremented by the value 1 (step
880), the value obtained by multiplying the reduction rate M in the main scanning direction by the variable i.
Is greater than the maximum value xmax in the main scanning direction
(Step 890). Here, it is determined that it is not large
Then, the processing returns to step 830,
The processing of step 890 is repeatedly executed. Repeat steps 830 to 890
The highest priority pixel data for each MxN pixel block.
Is selected and output to the color monitor 53. Subsequently, the variable j is incremented by the value 1 (step
900), the above processing is the target of processing
It is determined whether the process has been completed for the entire image data (scan
Step 910). Here, it is determined that the process has not been completed
Then, the process returns to step 820.
Step 910 is repeatedly executed. Such repetition
Processing in the sub-scanning direction for each MxN pixel block
The highest priority pixel data is output to the color monitor 53
If it is determined in step 810 that all data has been completed, this processing
Turns and ends. In this way, it is registered in the priority generation code table TBL.
One color per pixel block according to the priority
And the reduced density image (reduced image) of the selected color
Painted. Therefore, part of the line drawing may be missing.
Generate a reduced image that is easy to see and faithfully reproduces the current image
It has the effect that it can be done. Also, make sure the original image contains thin lines, as shown below.
Line is cut on the reduced image
Sometimes. On the other hand, if special low density is achieved,
Lines do not break even on reduced images.
Is displayed relatively thick, so the color change on the line
It has the advantage of being cheap to detect. FIG. 14A shows an image containing a thin line L, FIG. 14B
Is a reduced image obtained by specially reducing the density of the image in Fig.14A.
It is a figure showing an image. As shown in these figures,
, The line L in the 2x2 pixel block
If any pixel is included, the pixel
The color of the pixel corresponding to the lock becomes the same color as the color of the line L.
Therefore, when the line L is extremely thin (for example, the width of the line L is 1).
Low density in the reduced image)
There is no line break due to the conversion process. The image in Fig. 14C is a reduced image created by the thinning process.
Yes, at the upper left pixel of each 2x2 image block shown in FIG. 14A.
It is a composed image. When the thinning process is performed,
As shown in the figure, a line break occurs due to the thinning process.
Sometimes. Therefore, a special low-density treatment can be performed in the present invention.
Display only the line breaks in the original image on the color monitor 53.
This shows that line breaks can be detected more reliably.
There is a point. Also, as can be seen by comparing FIG. 14B and FIG. 14C,
When a reduced image is generated by special low density, the line
Because it is displayed relatively thick, the color change part on the line
Is easy to find, and therefore easy to detect broken lines.
There is a point.

【The invention's effect】

As described above, according to the first aspect of the present invention, an image in which different colors are assigned to mutually independent area portions is displayed. Therefore, in a line drawing portion where a line break exists, before and after the line break is different. Displayed in color. Accordingly, there is an effect that a line break can be easily detected only by finding a line drawing portion having a different color. Also. According to the invention described in claim 2, as a method of extracting a representative pixel in a pixel block in order to generate a reduced image to be displayed, priority of a color is determined in advance, and each pixel is determined according to the priority. If the representative pixel of the block is extracted, even a thin line drawing is represented as a relatively thick line drawing on the reduced image. Accordingly, it is possible to easily recognize a change in the color of the line drawing portion, and it is possible to more easily detect a broken line portion. Further, according to the third aspect of the present invention, before designating a processing target region, an independent region portion of the entire line drawing image is displayed in a different color and displayed inside a line drawing element which should constitute a closed region. Since the processing target area is specified so as to include a line drawing element whose color is the same as the external color, only the area including the line break is specified as the processing target for the line drawing element that should constitute the closed area Thus, there is an effect that the line break detection processing can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration diagram of an image processing apparatus which performs line break detection processing of an image to which an embodiment of the present invention is applied. FIG. 2 is a block diagram showing line break detection processing and connection processing. 3 is a plan view showing an example of the composition, FIGS. 4A and 4B are explanatory diagrams showing the configuration of run-length data, and FIGS. 5A to 5C are examples of the embodiment. FIG. 6 is a diagram showing a system color table showing the correspondence between system color numbers and display color numbers, and FIG. 7 is an enlarged view of a region including a line break. FIG. 8 is a diagram showing a processing window used for the region separation process, FIGS. 9A to 9D are explanatory diagrams showing the procedure of the region separation process, FIG. 10 is a diagram showing the same system color table, FIG. 11 is a flowchart showing a detailed procedure of the special low-density processing, FIG. 12 is a diagram illustrating a priority generation code table, FIG. 13 is a diagram illustrating an example of an image to be subjected to special low-density processing, FIG. 14A is a diagram illustrating an example of an image including a thin line, FIG. 14B and FIG. 14C are diagrams showing images obtained by reducing the density. BC: Intaglio, C: Circle shape CP1, CP2 ... Line break Ns: System color number PR: Processing target area PR1, PR2 ... Split processing area R1-R6: Separation area TBL: Priority Generated code table

Claims (3)

(57) [Claims] 1. A method for detecting a broken line portion of a line drawing by processing image data of the line drawing image, comprising: (a) a step of designating a processing target area in the line drawing image displayed on the display means; (B) dividing the processing target area into a plurality of divided areas; and (c) separating each of the plurality of divided areas by a boundary line of a different pixel value based on a pixel value assigned to each pixel. Recognizing the mutually independent area portions, and assigning different colors to the mutually independent area portions,
(D) displaying the image of the processing target area on the display means while separately painting each area portion with the assigned color; and (d) a line drawing part of the image displayed in the step (c), which is different in color. Detecting a line break existing in the line drawing portion by displaying the displayed portion. 2. The method according to claim 1, wherein in the step (c), the processing target area is divided into pixel blocks each having a predetermined shape composed of a plurality of pixels. The priority of the color of the pixel to be extracted as a representative pixel in the block is determined in advance, the representative pixel is extracted from each pixel block according to the priority, and a reduced image represented as a set of extracted representative pixels is generated. A line break detecting method including a step of displaying on a display means. 3. The line break detecting method according to claim 1, wherein the step (a) comprises: assigning different colors to mutually independent area portions in the line drawing image, and assigning each area with the assigned color. Displaying the line drawing image on the display means while separately painting the portion, comparing the internal color and the external color of the line drawing element which should constitute the closed area, and determining whether the internal color and the external color are the same. A line break detecting method including a step of designating a processing target area so as to include an element.