JPH06339037A - Boundary picture correcting method for pattern and line drawing - Google Patents

Abstract

PURPOSE:To improve the quality of a picture by preventing a void generated at a boundary between a line drawing and a pattern from being noticeble. CONSTITUTION:A circumference picture indicating a circumference area #11 constituted of pattern picture elements including a circumference between a line drawing area #1 and a pattern area #3, and the pattern area #3 inside the circumference area, is prepared. The circumference picture is prepared by operating a special thinning-out processing to the line drawing. A correction window W1 is simultaneously moved on the circumference picture and the pattern. When a central picture element CP of the correction window W1 is present in the circumference area #11, the dot area rate of the central picture element is corrected by averaging the dot area rate of the central picture element and the dot area rate of the peripheral picture element of the correction window W1 included in the pattern area #3. Thus, the dot area rate of each pattern picture element in the circumference area can be corrected by operating the above mentioned processing while moving the correction window W1 on a picture plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting an image at the boundary between a line drawing and a pattern, and more particularly to a technique for making white spots at the boundary inconspicuous.

[0002]

2. Description of the Related Art An image of one page of a printed matter such as a catalog or a pamphlet is usually composed of a combination of a line drawing and a design. At this time, the pattern may be cut out only in a necessary portion and attached to the line drawing. Figure 1
FIG. 7 is an explanatory diagram showing a process of cutting out a pattern and pasting it into a line drawing. FIG. 1 (A) shows the design before cutting out,
A high-density portion indicated by diagonal lines is included in the low-density background. Here, it is considered to perform a process of cutting out only the high density portion. In the cutout, the operator specifies the contour of the portion to be cut out, but the specified contour may deviate from the true contour of the desired cutout portion, as shown by the broken line in FIG. The picture portion PE cut out in this manner includes the low density portion LD in a part of the outer circumference. FIG. 1B is a line drawing LM of the cut-out picture part PE.
The state of being pasted inside is shown.

[0003]

When the density of the line drawing LM is relatively low, the low density portion LD of the cut out picture portion PE is not so noticeable. However, when the line drawing LM has a relatively high density, the low density portion L of the cut out picture part PE
There is a problem that D is noticeable as a white spot and the image quality is deteriorated. If the image is simply modified so that the density of the low-density portion LD is increased, the color tone of the modified portion differs from that of the other pattern portion, which causes a problem of degrading the image quality.

The present invention has been made in order to solve the above-mentioned problems in the prior art, and it is possible to improve the quality of an image by making white spots occurring at a boundary between a line drawing and a pattern inconspicuous. To aim.

[0005]

In order to solve the above-mentioned problems, the boundary image correction method according to the present invention comprises:
(A) a step of preparing line drawing data representing a division between a line drawing area and a picture area on the image plane at a first resolution; and (B) a picture corresponding to a second resolution lower than the first resolution. A step of preparing picture data representing a picture in the picture area for each pixel; (C) a border area composed of picture pixels including a border between the line drawing area and the picture area; A step of creating boundary line data indicating the picture area inside the line area at the second resolution based on at least one of the line drawing data and the picture data; and (D) the boundary data and the picture data. By identifying the color component of each picture element pixel in the boundary area by collating with, the color component of each picture element pixel in the boundary area and within a predetermined range from each picture element pixel in the boundary area. By performing a predetermined averaging processing to the color component of the picture pixels of the picture area that is present, and a step of correcting the color components of each picture pixel in the boundary area.

Although it is difficult to specify the position of the picture element pixel forming the boundary line only with the picture pattern data, the position of the picture element pixel forming the boundary line can be specified by collating the boundary line data with the picture pattern data. . Since the color components of the picture pixels in the boundary area and the color components of the picture pixels in the picture area within a certain range from the picture pixel are averaged, the color of the picture pixels in the boundary area is calculated. The ingredients can be high. In addition, since the color components of the picture pixels in the picture area are used in the averaging process, an image in which the picture tone changes smoothly without jumping sharply in the picture area can be obtained.

[0007]

FIG. 2 is a conceptual diagram showing the overall construction of an image processing system including an apparatus for correcting an image at the boundary between a line drawing and a pattern by applying one embodiment of the present invention and its processing contents. This image processing system includes a reading scanner 20 and a character writing device 3.
0, clipping device 40, page layout device 50
And the image fitting processing device 60 and the boundary correction device 70.
And an image output device 80 and a recording scanner 90.

The reading scanner 20 scans a pattern arranged on an image of one page (hereinafter referred to as "one page image") to read the pattern data OP1 to OP3. Typesetting device 3
In 0, the character string arranged in the one-page image is input. The cutout device 40 cuts out a pattern as necessary and creates mask data MD of the cutout portion. The mask data MD is expressed in a format such as vector data or a page description program. Page layout device 50
Then, the operator forms the one-page image IM based on the pattern data OP1 to OP3, the thinned pattern data SP1 to SP3 obtained by thinning them, the mask data MD, and the character string data CD. The one-page information OI representing the layout of the one-page image IM is expressed in the form of vector data or a page description program.

The image embedding processing device 60 creates one-page picture data CT and one-page line drawing data LW representing the whole one-page image IM based on the one-page information OI and the picture data OP1 to OP3. Boundary correction device 7
Reference numeral 0 is a device for correcting the boundary between the line drawing and the pattern, as will be described later in detail. In the boundary correction, the one-page line drawing data LW is not corrected and only the one-page pattern data CT is corrected.

The image output device 80 generates a halftone dot signal DS for outputting the one-page image IM. The character / line drawing area is also represented by a halftone dot signal, and the solid dot portion has a halftone dot area ratio of 100%. The recording scanner 90 uses the halftone dot signal D
According to S, the halftone-plate image HI of the one-page image IM is recorded on a recording medium such as film or photographic paper. Normally, Y (yellow), M (magenta), C (cyan), K
The four-color halftone images of (black) are recorded.

FIG. 3 is a block diagram showing the internal structure of the boundary correction device 70. The boundary correction device 70 includes the following components. (A) CPU 100: Controls each unit of the boundary correction device 70 and executes boundary correction for the one-page picture data CT. The CPU 100 and the following components are connected to each other via a bus 102. (B) ROM 104: a memory that stores a processing program executed by the CPU 100. By this processing program, the processes of various means (line drawing / pattern overlapping display means, line drawing thinning-out means, pattern correcting means (including averaging processing means)) described later are executed. (C) RAM 106: a memory for temporarily storing various data used for image processing, and a correction width table WT described later is also stored in the RAM 106. (D) Line drawing memory 108: A memory for storing the page 1 line drawing data LW. The line drawing memory 108 has a first memory area for storing the original one-page line drawing data LW and a second memory area for storing thinned line drawing data obtained by thinning the one page line drawing data LW. And an area. The thinned-out line drawing data corresponds to boundary line data used for boundary correction, as described later. (E) Design memory 110: Memory for storing the one-page design data CT in the bitmap format. (F) Keyboard / mouse I / O interface 11
2: An interface that receives inputs from the keyboard 114 and the mouse 116. (G) Display control unit 118: Color image CRT1
The interface used to transfer images to the 20 and display images. (H) Online input / output port 122: an interface for performing data communication with other devices in the image processing system (FIG. 2) through a network. (I) Magneto-optical disk interface 124: an interface for performing data transfer with the magneto-optical disk 126.

FIGS. 4A and 4B respectively show a pattern represented by the 1-page pattern data CT and a line drawing represented by the 1-page line drawing data LW, and FIG. 4C shows a 1-page image IM. Is shown. The line drawing on one page includes a background region R1, three mask regions R2, R3, and R4 to which the picture parts are respectively attached, and a character string.
The background region R1 is a region of comparatively high density, and is a tint (flat screen) or solid printing region. Of course, the line drawing on one page may include other figures (those that do not touch the boundary with the picture). In the present embodiment, character strings and other figures are not processed, so a description of how to handle character strings is omitted. Each area R1, R2, R3, R4
Are assigned color numbers # 1, # 2, # 3, and # 4, respectively.

FIG. 5 is an explanatory diagram showing a mutual relationship between the 1-page pattern data CT and the 1-page line drawing data LW in a specific area (area where a pattern and a line drawing have a boundary). When synthesizing the line drawing and the design, the line drawing represented by the one-page line drawing data LW is arranged on the design represented by the one-page design data CT, and the design in the mask area of the line drawing (indicated by diagonal lines in the figure) I think that only the part can be seen through.
That is, only the design in the mask area is pasted on the one-page image IM as a valid design portion.

As shown in FIG. 5, the line drawing pixel Pμ is usually smaller than the picture pixel Pe. In this embodiment, the length of one side of the line drawing pixel Pμ is ⅕ of the length of one side of the picture pixel Pe. In other words, the resolution of the line drawing is 5 times the resolution of the design. The 1-page line drawing data LW represents the mask area surrounded by the contour C1.
The page pattern data CT represents a pattern portion surrounded by a contour C2 corresponding to the contour C1. Since the contour C1 is represented by the resolution of the line drawing and the contour C2 is represented by the resolution of the pattern, even if these contours AC1 and C2 are overlapped, they do not match. More specifically, the outline C2 on the pattern is at the boundary of the outer periphery of the pattern pixel including the outline C1 on the line drawing.
In the one-page picture data CT, only the color components of the picture pixels inside the contour C2 are expressed, and the color components of other unnecessary portions are deleted. This is so that the image of the boundary between the patterns can be reproduced well even when the patterns are adjacent to each other.

FIG. 6 is an explanatory diagram showing the structure of the one-page line drawing data LW. As shown in FIG. 6A, the one-page line drawing data LW includes a line drawing data management section, a color palette section, and a run length data section. The line drawing data management unit includes data such as line drawing size, resolution, and file name.

As shown in FIGS. 6 (B) and 6 (C), the color pallet portion stores information corresponding to each color number as
The halftone dot area ratio (halftone dot%) of each color plate and the pattern priority flag Fy,
It contains Fm, Fc and Fk. For the color plate with the picture priority flag of 1, the pattern data has priority, and for the color plate with the picture priority flag of 0, the line drawing data has priority.

FIG. 7 is an explanatory diagram showing the correspondence between the color numbers represented by the color palette CC and the dot area ratio of each color plate. The color number # 1 of the background region R1 indicates that the halftone dot area ratios of the Y and M plates are 50%, and the halftone dot area ratios of the C plate and K plate are 0%. Also, the mask region R
For color numbers # 2, # 3 and # 4 of 2, R3 and R4,
"T (transparency)" is registered for all color plates. The color plate in which the transparency is registered indicates that the value of the pattern priority flag is 1. That is, the color number # for the regions R2, R3, R4
In Nos. 2, # 3 and # 4, the pattern data is adopted in preference to the line drawing data for all the color plates. The transparency can be set for each color plate. For example, for color number # 2, set transparency on K plate,
It is also possible to set a desired halftone dot area ratio to the other three plates.

The run length data section includes the run length data shown in FIG. 6 (D). One unit of run length data (hereinafter, referred to as “unit run length data”) includes a run length and a color number for each run on the scanning line of one page line drawing (FIG. 4B). Is. The data shown in FIG. 6D corresponds to the scan line L in FIG.
1 is run length data.

FIG. 8 is a conceptual diagram showing the structure of the one-page picture data CT. FIG. 8A shows the picture data for one pixel including the data indicating the halftone dot area ratio of each YMCK. FIG. 8B shows a pixel array of pattern data on the image plane. That is, the pixels are arrayed in the scanning line sequence along the main scanning direction Y, and the data of FIG. 8A is stored in the pattern memory 110 according to the array order.

FIG. 9 is a flow chart showing the processing procedure in this embodiment. In step S1, the page 1 line drawing data LW and the page 1 pattern data CT are read from the magneto-optical disk 126 and written in the line drawing memory 108 and the pattern memory 110, respectively. In step S2, based on the data stored in the line drawing memory 108 and the pattern memory 110, line drawing / pattern overlapping display means (R in FIG. 3).
OM104) displays the pattern and the line drawing on the color CRT 120 in a superimposed state.

In step S3, the operator selects color C
By observing the image displayed on the RT 120, it is determined whether or not there is a design component that requires boundary correction. This includes
Not only observing the entire page image, but also observing the image of each divided area that divides the page, or the image of the area of the specified range by appropriately enlarging (these methods are conventional techniques of image processing, Since it is not directly related to the present invention, detailed description will be omitted). By observing the enlarged display image, as shown in FIG. 1 (B), it is possible to easily determine whether or not the boundary correction is necessary by checking whether or not there is a white spot around the picture part. can do. If there is a pattern component that requires boundary correction, in step S4, there are a mode in which boundary correction is performed for all pattern components (auto mode) and a mode in which boundary correction is performed only for specific pattern components (manual mode). The operator selects one of them.

When the auto mode is selected in step S4, the correction width CW for boundary correction is set in step S5.
Is specified. The correction width CW is a value indicating the size of a correction window (described later) used for boundary correction. In auto mode, the same correction width CW is applied to all pattern parts.
Is applied.

When the manual mode is selected in step S4, the operator selects a pattern part to be subjected to boundary correction in steps S6 and S7, and
The correction width CW is designated for each selected picture part.

In step S8, the value of the correction width for each pattern part is registered in the correction width table WT shown in FIG. The correction width table WT is a table showing the correspondence between the color numbers of the mask areas R2, R3, R4 (see FIG. 4B) on the line drawing and the correction width CW. In this embodiment, the correction widths CW for the color numbers # 2 and # 3 of the mask areas R2 and R3 are set to 2 and 1, respectively. The value of the correction width CW is 0 for the color number # 4 of the mask region R4.
However, this indicates that the operator did not set the pattern component of the mask region R4 as the target of the boundary correction.

In step S9, line drawing thinning means (see FIG. 3).
Of ROM 104) executes the priority thinning process on the one-page line drawing data LW to create thinning line drawing data having the same resolution as the pattern. FIG. 11A shows a line drawing before the priority thinning process, and FIG. 11B shows a line image after the priority thinning process (referred to as a “boundary line image”). Figure 11
The shaded area in (A) is the mask region R shown in FIG.
3 corresponds to the background area R1. The priority thinning-out process is a type of thinning-out process for replacing an N × N pixel block with one representative pixel, and is a process for determining the color number of the representative pixel according to a priority designated in advance. Here, N is the ratio of line drawing and pattern resolution (= 5)
Is. In this embodiment, when determining the color number of the representative pixel, the color number designated as the target of boundary correction in step S6 (referred to as "priority color number") is given priority over other color numbers. Specifically, the color number of the representative pixel is determined as follows.

(1) When all the line drawing pixels in the N × N pixel block have a priority color number: The priority color number is selected as the color number of the representative pixel. When a plurality of types of priority color numbers are included in the N × N pixel block, any priority color number may be selected.

(2) When all the line drawing pixels in the N × N pixel block have a color number other than the priority color number (referred to as "non-priority color number"): As the color number of the representative pixel, the non-priority color Select a number. When a plurality of non-priority color numbers are included in the N × N pixel block, any non-priority color number may be selected.

(3) When line drawing pixels having priority color numbers and line drawing pixels having non-priority color numbers are mixed in the N × N pixel block: a new color number is set as the color number of the representative pixel. Assigned. Since this new color number indicates the boundary area, it will be referred to as a "border color number" below.

The representative pixel represented by sand in the boundary image shown in FIG. 11B has a mixture of a priority color number (# 3) and a non-priority color number (# 1) in the line drawing of FIG. 11A. Corresponding to the pixel block being processed. At this time, the new color number # 11 is designated as the boundary color number in accordance with (3) above. The size of the pixel in the boundary image is the same as that of the picture pixel. In other words, the thinned line drawing has the same resolution as the pattern.

The boundary BL between the boundary color number # 11 and the non-priority color number # 1 in the boundary image coincides with the contour of the picture part OP2 shown in FIG. 4 (A). The purpose of creating the boundary image is to know the boundary area (area shown by sand in FIG. 11B) composed of picture pixels including the boundary on the line drawing. In the picture data, only the values of four color components (that is, the dot area ratio) are given to each picture pixel, and the data indicating the contour of the picture part is not included. Therefore, if a boundary image is created and collated with the design, the boundary area on the design can be known.

Since the priority thinning-out process is described in detail in Japanese Patent Application Laid-Open No. 4-134570 disclosed by the present applicant, the detailed processing procedure will be omitted.

In step S9, the boundary line image data thus obtained is further stored in the line drawing memory 108, and as shown in FIG.
The boundary color number is registered in T in correspondence with the color number of the mask area.

In step S10, the pattern correction means (see FIG.
(See ROM 104) for performing the boundary correction. 12
FIG. 6 is an explanatory diagram showing a boundary correction method. Boundary correction is
Correction window W1 or W2 (FIG. 12 (A),
(B)) is simultaneously moved on the boundary image (FIG. 12C) and on the pattern (FIG. 12D). This movement is equivalent to collating the boundary line image with the design.

The correction windows W1 and W2 are operators in which a predetermined weight is assigned to each pixel in the window. FIG. 12A shows the first correction window W1 used for the area of the boundary color number # 11 (FIG. 10B) where the correction width CW is 1, and FIG. 12B shows the correction width CW. The second correction window W2 used for the area having the boundary color number # 10 of No. 2 is shown.

When the color number of the central pixel CP of the correction window W1 is the boundary color number # 11 on the boundary image of FIG. 12C, the halftone dot of the picture pattern at the position corresponding to the central pixel CP. The area ratio is corrected. As a result, FIG.
The halftone dot area ratio of the pattern (D) is corrected as shown in FIG. This correction averages the halftone dot area ratio in the central pixel of the correction window W1 and the halftone dot area ratio of the picture pixels existing in the mask area (area of color number # 3) among the peripheral pixels of the correction window W1. It is executed by the process. In the example of FIGS. 12C and 12D, the correction window W
The halftone dot area ratio of the central pixel of 1 is 70%, and the halftone dot area ratios of pixels that are peripheral pixels of the correction window W1 and exist in the mask region are 90%, 80%, and 80%.
Therefore, the corrected halftone dot area ratio in the central pixel is 80%.
Becomes In this way, the halftone dot area ratio of the pattern of the pixel having the boundary color number # 11 in FIG.
It is corrected as shown in (D) to (E). In addition, in this correction process, 1 stored in the pattern memory 110 is stored.
The value of the color component of the page picture data CT is directly rewritten. Further, this boundary correction is executed for each of the four colors YMCK.

As can be seen by comparing the halftone dot area ratios of FIGS. 12D and 12E, the picture pixel having the halftone dot area ratio of 20% before the correction is 50 to 60 after the boundary correction. It has a dot area ratio of%. Now, in FIG. 12D, a pixel having a halftone dot area ratio of 20% is a low density portion LD shown in FIG.
It can be understood that the low density portion LD is less noticeable in the pattern corrected as shown in FIG. 12 (E).

Boundary correction using the second correction window W2 shown in FIG. 12B is performed in the same manner as above. That is, the process of averaging the halftone dot area ratio in the central pixel of the correction window W2 and the halftone dot area ratio of the picture pixels existing in the mask area among the 20 peripheral pixels in the correction window W2 is executed. . In the second correction window W2, since the number of peripheral pixels referred to in the averaging process is large, the weight of the central pixel is smaller than that in the first correction window W1. That is, in the averaging process, when it is desired to reduce the weight of the pixels existing in the boundary area, 2 may be designated as the correction width CW.

When the boundary correction is completed for the entire one-page design data CT, the line drawing and the design are superimposed again based on the one-page line drawing data LW and the corrected one-page design data CTa in step S11 (FIG. 9), and the color is reproduced. It is displayed on the CRT 120. The operator checks the displayed image and if a good image is obtained (= O
1) line drawing data L for one page in step S12.
W and the corrected one-page picture data CTa are output to the image output device 80 (FIG. 2). The image output device 80 generates a halftone dot signal DS based on these data and transfers it to the recording scanner 90, and the recording scanner 90 responds to the 4
Record a halftone image for each color.

If it is necessary to make further correction in step S11 (= NO), the process returns to step S3.
The processes of steps S3 to S10 may be executed again.

According to the above-mentioned embodiment, when there is a low density portion LD which is conspicuous as shown in FIG. 1B, the boundary correction is executed to increase the halftone dot area ratio in the boundary area of the picture part. As a result, the low-concentration portion can be made inconspicuous. Further, in the boundary correction, since the color components of the picture elements in the picture area are used for the averaging process, it is possible to eliminate the jump of the hue in the picture parts and smooth the change in the hue in the picture parts. it can.

If not only the boundary area between the line drawing and the pattern but also the interior of the pattern part has a low density,
A low-concentration portion LD that is conspicuous at the boundary as in (B)
Does not appear, it is not necessary to perform boundary correction. In this case, the operator does not have to select the design part as the target of the boundary correction in step S6 of FIG.

The present invention is not limited to the above-described embodiments, but can be carried out in various forms without departing from the scope of the invention, and the following modifications can be made.

(1) FIG. 13 shows the correction window.
Those shown in (A) and (B) can also be used. The correction window W3 shown in FIG. 13A is shown in FIG.
The weight in the averaging process is different from that shown in FIG. 3, and the weight of the central pixel in the averaging process is relatively small. Correction window W4 shown in FIG. 13 (B)
Not only have different weights from those shown in FIG. 12B, but also have different window shapes. Various other shapes can be adopted as the shape of the correction window and the weight for averaging.

(2) As a method of creating the boundary line image shown in FIG. 11B, a method other than the method of preferentially thinning out the one-page line drawing data LW can be considered. For example, in the one-page pattern data CT, the dot area ratios of all the color components are set to 100% in the areas other than the effective pattern parts. By doing this, the dot area ratio of all color components is 1
The boundary line image shown in FIG. 11B can be obtained by investigating the boundary of the picture pixel which is 00%. The boundary image of FIG. 11 (B) is generally an area composed of picture pixels including a boundary between a line drawing and a picture (that is, an area having a boundary color number # 11) and a picture area inside the boundary (that is, a color). Data of the area # 3). Such boundary data is the page 1 line drawing data L.
It can be created based on at least one of W and the one-page pattern data CT.

The boundary line data may be stored in the line drawing memory 108 in the form of run length data, or may be stored in the pattern memory 110 in the form of bitmap data. When the border line image data is stored in the picture memory 110, the memory area for that is set as one page picture data C.
Prepare separately from T.

(2) The special thinning in step S9 and the boundary correction in step S10 may be executed for every three scanning lines. That is, as shown in FIG.
In the second processing, after the boundary image corresponding to the three scanning lines L1 to L3 on the pattern is obtained by special thinning, boundary correction is performed on the central scanning line L2. In the second processing, one scanning line is updated to prepare a boundary image including the scanning lines L2 to L4, and the boundary correction is performed on the scanning line L3 at the center thereof. When processing is performed in this way, it is sufficient to store a boundary line image including three scanning lines.
There is an advantage that the amount of memory required for processing can be reduced.
It is preferable to use a line memory for three scanning lines as the memory for storing the boundary line image including three scanning lines.

(3) When the cutting precision of the pattern part is poor, the low-density part LD (FIG. 1) in the peripheral part of the pattern part is used.
It is also conceivable that the width of (B)) extends over two picture elements.
In such a case, as shown in FIG. 15, a new color number (quasi-boundary color number # 21) is assigned to a pixel existing inside (a pixel area side) of the pixel to which the border color number # 11 is assigned. . The position of the pixel to which the quasi-boundary color number # 21 is assigned is the boundary color number # 11 and the color number # 3 of the picture area for this boundary line image after the boundary line image shown in FIG. Can be determined by executing a thinning process for.

After obtaining the boundary image to which the boundary color number # 11 and the quasi-boundary color number # 21 are obtained, first, the correction window having the correction width CW = 1 is used for the quasi-boundary color number # 21. To perform boundary correction. At this time, the border color number #
The halftone dot area ratio of pixels having 11 is not used in the averaging process. Next, the boundary correction is performed on the boundary color number # 11 using the correction window having the correction width CW = 2. On this occasion,
The halftone dot area ratio of the pixel having the quasi-boundary color number # 21 is not used in the averaging process. If the boundary correction is executed by such a procedure, it is possible to correct the halftone dot area ratio of the boundary pixels over the width of two pixels.

(4) In the above embodiment, the boundary correction device 70
Was arranged in the middle of the image embedding processing device 60 and the image output device 80, but the boundary correction device 70 can also be arranged at another position in this image processing system. For example, in the image output device 80, the page 1 line drawing data L
When generating the halftone dot signal DS from W and the one-page pattern data CT, the function of the above-described image output device 80 may be performed by dedicated hardware provided in the image output device 80. However, at this time, the operator in advance designates the pattern component and the correction width to be subjected to the boundary correction in the image fitting processing device 60. Further, the image embedding processing device 60 and the page layout device 50 may have the function of the image output device 80.

[0050]

As described above, according to the boundary correction method of the present invention, it is possible to improve the quality of an image by making white spots occurring at the boundary between a line drawing and a pattern inconspicuous. There is.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a white spot that occurs when a pattern is cut out and pasted in a line drawing.

FIG. 2 is a conceptual diagram showing an overall configuration of an image processing system that performs boundary correction by applying an embodiment of the present invention.

FIG. 3 is a block diagram showing an internal configuration of a boundary correction device.

FIG. 4 is an explanatory diagram showing a line drawing, a design, and a one-page image.

FIG. 5 is an explanatory diagram showing a mutual relationship between a line drawing and a design.

FIG. 6 is a conceptual diagram showing the structure of line drawing data.

FIG. 7 is an explanatory diagram showing the contents of a color palette.

FIG. 8 is a conceptual diagram showing the structure of design data.

FIG. 9 is a flowchart showing a processing procedure of boundary correction.

FIG. 10 is an explanatory diagram showing the contents of a correction width table.

FIG. 11 is an explanatory diagram showing a priority thinning method.

FIG. 12 is an explanatory diagram showing a boundary correction method.

FIG. 13 is an explanatory diagram showing a modified example of a correction window.

FIG. 14 is an explanatory diagram showing a method of performing boundary correction for every three scanning lines.

FIG. 15 is an explanatory diagram showing a processing method when the boundary area has a width of 2 pixels.

[Explanation of symbols]

 20 ... Reading scanner 30 ... Characterizing device 40 ... Cropping device 50 ... Page layout device 60 ... Image fitting processing device 70 ... Boundary correction device 80 ... Image output device 90 ... Recording scanner 100 ... CPU 102 ... Bus 104 ... ROM 106 ... RAM 108 ... Line drawing memory 110 ... Design memory 112 ... I / O interface 114 ... Keyboard 116 ... Mouse 118 ... Display control unit 120 ... Color CRT 122 ... Online input / output port 124 ... I / O interface 126 ... Magneto-optical disk BL ... Boundary C1, C2 ... Outline CD ... Character string data CC ... Color palette CP ... Correction pixel center pixel CW ... Correction width DS ... Halftone dot signal Fy, Fm, Fc, Fk ... Pattern priority flag HI ... Halftone plate image L1 to L4 Scanning line LD Low density area LM Line drawing MD Mask data OP1 to OP3 ... Design data PE ... Design portion Pe ... Design pixel Pμ ... Line drawing pixel R1 ... Background area R2 to R4 ... Mask area W1 to W4 ... Correction window

Claims (1)

[Claims] 1. A method for correcting an image at a boundary between a line drawing and a picture on the same image plane, comprising: (A) a line drawing showing a division between the line drawing area and the picture area on the image plane with a first resolution. A step of preparing data, (B) a step of preparing picture data representing a picture in the picture area for each picture pixel corresponding to a second resolution lower than the first resolution, and (C) the line drawing Boundary line data indicating a boundary line region formed of pattern pixels including a boundary line between the region and the pattern region and a pattern region inside the boundary line region at the second resolution are the line drawing data and Creating based on at least one of the pattern data,
(D) The color component of each picture pixel in the border area is specified by collating the border data with the picture data, and the color component of each picture pixel in the border area and the border By performing a predetermined averaging process on the color components of the picture pixels in the picture area existing in a predetermined range from the picture pixels in the line area, the color of each picture pixel in the boundary area A boundary image correction method comprising: a step of correcting a component.