JP2698382B2 - Image composition method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image synthesis method, and more particularly to an image synthesis method for synthesizing a halftone image.

(Prior Art) Recently, in the information-oriented society, processing of halftone images has been demanded.
It is required to create one image.

However, if the halftone image is synthesized by simply connecting the boundaries of the two images, the boundary between the two images becomes an unnatural image compared to the surrounding images, and the image as a whole becomes uncomfortable. It becomes a certain image.

Therefore, conventionally, an image memory for storing analog data or multi-valued data of two images to be combined is provided, and an overlapping portion of both images is provided at a boundary portion between the two images to be combined, and according to a position of the overlapping portion. Image data of both images is output at a ratio determined by a predetermined method to blur the boundary between the two images.

(Problems to be Solved by the Invention) However, in such a conventional image synthesizing method, an image is synthesized with image data at the stage of analog data or multi-valued data. A large-capacity image memory is required, and an apparatus for performing image synthesis is expensive.

(Objects of the Invention) Accordingly, the present invention binarizes image data of two images to be combined with the same dither matrix and combines the two images at a position where the dither matrix is continuous by a predetermined method. By arranging white (or black) pixels according to the same dither matrix as the number of white (or black) pixels in a predetermined area of the composite portion, two images can be naturally formed based on the binarized image data. It is an object of the present invention to create a composite image without a sense of incongruity, reduce the capacity of an image memory, reduce the price of a device that performs image composition, and improve the image quality of the composite image.

(Constitution of the Invention) The present invention provides an image synthesis method for synthesizing two types of images obtained by binarizing multi-valued data with the same m × n dither matrix to achieve the above object. In synthesizing the two types of images, the dither matrix used for binarizing the multi-valued data of each image is synthesized at a position where the arrangement in each region is continuous at the boundary position between the two images, and both images are synthesized at the boundary portion. The image is overlapped by a predetermined multiple of m pixels in the main scanning direction and by a predetermined multiple of n pixels in the sub-scanning direction, and the overlapping portion is divided into m × n small regions. The number of black pixels or white pixels in each small area is detected for each image, and the new number of black pixels and white pixels in the small area are determined based on the detection result and the position of the small area in the overlapping portion. Set the number and the m × n dither mat Which is characterized in that setting the position of the new black and white pixels in the small region on the basis of the box.

And (2) an image synthesizing method for synthesizing two types of images obtained by binarizing multi-valued data using the same m × n dither matrix, and when synthesizing the two types of images, the multi-level The arrangement in each area of the dither matrix used for the binarization of data is synthesized at a position where both images are continuous at a boundary position between the two images, and m pixels in the main scanning direction including pixels of both images at the boundary portion, and sub-scanning direction A small area of n pixels is set, and the number of black pixels or white pixels in the small area is detected, and the new arrangement of the detected number of black pixels and white pixels is associated with the m × It is set based on n dither matrices.

 Hereinafter, a specific description will be given based on examples of the present invention.

FIGS. 1 to 6 show an embodiment of the first aspect of the present invention, which is applied to an image processing apparatus.

FIG. 1 is a functional block diagram of the image processing apparatus 1. The image processing apparatus 1 includes two dither processing circuits 2, 3, image memories 4, 5, a synthesis processing circuit 6, an image memory 7, a printer 8, and a display 9. Etc. are provided.

The dither processing circuits 2 and 3 have the same m × n dither matrix (for example, a 4 × 4 dither matrix as shown in FIG. 2) and perform dither processing on input multi-valued image data. Image memory 4 as binary image data
And outputs it to the image memory 5. The image data input to the dither processing circuit 2 and the dither processing circuit 3 is a CCD (Cha
The digital data is obtained by digitally converting analog data obtained by reading an image of a document using a rge coupled device or the like into multivalued data having a size corresponding to the size of the analog data.

The image memories 4 and 5 each have a predetermined capacity necessary for performing image synthesis in the synthesis processing circuit 6, and store image data that has been binarized by the dither processing circuit 2 and the dither processing circuit 3, respectively.

The synthesizing circuit 6 synthesizes an image of the image data stored in the image memory 4 and the image memory 5 based on a predetermined image synthesizing method to be described later and outputs the synthesized image data to the image memory 7. Is temporarily stored on a recording paper by the printer 8 and displayed on the display 9.

 Next, the operation will be described.

Now, description will be made assuming that the image A and the image B are combined as shown in FIG.

Image data A (multi-valued data) of image A is input to dither processing circuit 2, and image data of image B (multi-valued data) is input to dither processing circuit 3. The image data A and the image data B are stored in the image memory 4 and the image memory 5, respectively.
Are dithered by the same dither matrix, and stored in the image memory 4 and the image memory 5 as binary data.

The synthesis processing circuit 6 synthesizes the image A and the image B based on the image memory 4 and the image data stored in the image memory 5. At this time, at the boundary position between the image A and the image B shown in FIG. The dither matrix used for binarizing the data A and the dither matrix used for binarizing the image data B are synthesized so as to be continuous. That is, the image data A and the image data B are binarized using the same dither matrix. When the image A and the image B are combined, the dithering is performed at the boundary position, for example, as indicated by Z in FIG. The composition is performed so that the dither values of the matrix are continuous.

When combining the image A and the image B, the combining processing circuit 6 provides an overlapping portion P of the image A and the image B at the boundary between the image A and the image B as shown in FIG. The overlapped portion P has a pixel number in the main scanning direction (x direction in FIG. 3) which is a predetermined number (l times) of the number m of rows in the main scanning direction of the dither processing circuit 2 and the dither matrix of the dither processing circuit 3. And the number of pixels in the sub-scanning direction (y direction in FIG. 3) is a predetermined number (l times) of the number n of columns of the dither processing circuit 2 and the dither matrix of the dither processing circuit 3 in the sub-scanning direction. Minute width. A new image is set in the overlapping portion P. When setting this new image, the overlapping portion P is divided into small areas of the same m × n pixels as the dither matrix of the dither processing circuit 2 and the dither processing circuit 3. The number of black pixels (or white pixels) of the image is set, and the arrangement of the black pixels (or white pixels) in the small area is determined. That is, as shown in FIG. 4, first, the small area fraction S _b the number of black pixels in both the small area fraction S _a and B images of the A image that overlaps a small area Sp (or the number of white pixels) (Fig. 4 (Black pixels are indicated by oblique lines). Next, the number of black pixels (or the number of white pixels) of the image after the synthesis of the small area Sp is calculated based on a predetermined calculation formula corresponding to the position of the small area Sp at the overlapping portion P. For example, as shown in FIG. 5, when the image A and the image B are combined, the image A and the image B have an overlapping portion P, and the overlapping portion P is divided into small areas P ₁ , P ₂ ,. .., Pl, the number of black pixels of the image A in the small area P ₁ , P ₂ ,...
The number of black pixels BP ₁ , BP ₂ of the new image in each of the small areas P ₁ , P ₂ ..., Pl
..., BPl is obtained by the following equation.

This equation gives the two images combined by the small area Sp, namely
Depending on which one of the images A and B is closer, the number of black pixels close to the number of black pixels of the closer image is set as the number of black pixels of the new image. Therefore, image A and image B
The number of black pixels changes smoothly at the boundary between the image and the image, and an image with no discomfort is obtained.

When the number of black pixels of the new image in the small area Sp is determined, the determined number of black pixels is then used in the dither processing circuit 2 and the dither processing circuit 3 as shown in FIG. It is determined based on the same dither matrix as the dither matrix. That is, as shown in FIGS. 2 and 4, the dither matrix has thresholds arranged by the number of the matrices. Pixels having the smaller thresholds are set as black pixels. Pixels up to the number determined by are defined as black pixels. For example, in the case of FIG. 4, if the determined number of black pixels is seven, the image of the new small area NS is from the pixel position where the threshold value of the dither matrix is “1” to the pixel position where the threshold value is “7”. Are black pixels. This corresponds to a high possibility that a pixel at a pixel position where the threshold value of the dither matrix is small becomes a black pixel in the normal dither processing. Therefore, it is possible to obtain a natural image that does not feel uncomfortable with the image A and the image B that have been dithered with the same dither matrix.

In the case where the position of the black pixel of the new image is defined for each small region Sp, the position of the threshold value of the dither matrix corresponding to each small region Sp is the same as the arrangement shown in FIG. 2 or FIG. However, depending on the connection state of the dither matrix at the boundary position between the image A and the image B, the dither matrix set in the small area of m × n may have, for example, a threshold arrangement as shown in FIG. is there. In this case, the arrangement of the black pixels of the new image in each small area Sp is determined based on the threshold value of the dither matrix as shown in FIG. That is, the same threshold value arrangement as that of the dither matrix corresponding to the image combining position is used.

As described above, according to the present invention, the binary data dithered with the same dither matrix is stored in the image memories 4 and 5, and the image is synthesized based on the binarized image data. The capacity of the memories 4 and 5 can be reduced, and the price of the image memories 4 and 5 and the price of the image processing apparatus 1 can be reduced. In addition, the arrangement of the dither matrix as the entire image is maintained, the two images are combined so that the dither matrix is continuous even at the boundary, and an overlapping portion of the image is provided at the boundary,
The overlapping portion is divided into small areas corresponding to the size of the dither matrix, and for each small area, the number of black pixels (or the number of white pixels) of the original image in the small area and the Since the number of black pixels is determined based on the position and the determined black pixels and rearranged based on the original dither matrix, it is possible to obtain an image in which the boundary portion does not become unnatural and as a whole does not feel uncomfortable. it can. As a result, the quality of the synthesized image can be improved.

7 to 9 show an embodiment of the second aspect of the present invention.

FIG. 7 is a functional block diagram of the image processing apparatus 11, and the same components as those of the embodiment shown in FIG.

The image processing apparatus 11 includes dither processing circuits 2 and 3, image memories 4 and 5, a synthesis processing circuit 12, an image memory 7, a printer 8, a display 9, and the like.

The synthesis processing circuit 12 synthesizes the two image data stored in the image memories 4 and 5 that have been dithered by the dither processing circuits 2 and 3 and outputs the synthesized image data to the image memory 7. The synthesis processing circuit 12 synthesizes two images by the following method. That is, when the image A and the image B as shown in FIG. 8 are to be combined, the combining processing circuit 12 sets the boundary between the image A and the image B as in the embodiment shown in FIGS. The threshold arrangement of the dither matrix used to dither the image A at the position and the threshold arrangement of the dither matrix used to dither the image B are combined so that they are continuous, and at the boundary position between the two images, as shown in FIG. 9, it sets a small region S _K dither processing circuit 2 and the dither processing circuit 3 fraction same pixel as the dither matrix DM m × 6 used in. This small area _SK is a dither matrix
Set the equivalent of one DK, but including the boundaries,
An area including both the image A and the image B is set. Small area S _K
Setting, the small area S detects the number of black pixels (or the number of white pixels) in the _K, the small region based on the dither matrix DM using black pixels by the number detected by the dither processing circuits 2 and 3 newly relocated to S _K. At this time, black pixels are arranged by the number of black pixels sequentially from the pixel having the smaller threshold value of the dither matrix DM. For example, in the case of FIG. 9, if five black pixels (indicated by oblique lines in FIG. 9) are included in the small region S _K set at the boundary between the image A and the image B, the small region S _K The number of black pixels to be newly rearranged is five. The positions of the newly rearranged black pixels are positions from the pixel having the smaller threshold value of the dither matrix DM to five pixels (indicated by oblique lines in FIG. 9).

Therefore, the binarized image data is stored in the image memory 4,
5, and the image is synthesized based on the image data. Therefore, the capacity of the image memories 4 and 5 can be reduced, and the price of the image memories 4 and 5 and the image processing apparatus 11 can be reduced. Can be. In addition, the two images to be combined are combined so that the threshold arrangement of the dither matrix is continuous, and one small area of the dither matrix obtained by dithering the two images is set at the boundary position, and the black pixels in the small area are set. Has been rearranged based on the dither matrix corresponding to the small area, so that a natural image is obtained at the boundary portion, and the image changes smoothly. As a result, it is possible to obtain a good composite image without discomfort as a whole.

FIG. 10 is a diagram showing another embodiment of the second aspect of the present invention.

This embodiment is different from the embodiment shown in FIGS.
Setting small regions S _K to set the boundary portions of the two images to be combined is obtained by changing the.

That is, the boundary portion of the image A and the image B, upon setting a small region S _K containing boundary, sets the small region S _K containing substantially the same number of pixels of the image A and image B in the small regions S _K. This detects the number of black pixels in the small region S _K, repositioning based black pixels of the number detected in the dither matrix DM. In this case, setting the small area S _K to include equal number of pixels of both images, the small areas S _K as shown in FIG. 10 is set at a position deviated from the original threshold arrangement of a dither matrix DM There is. In this case, the dither matrix DM used to reposition the black pixels in the small region S _K, as shown in FIG. 10,
Employing a dither matrix NDM shifted in correspondence with the small region S _K from the original threshold arrangement.

Accordingly, in this embodiment, it is possible to reposition the black pixels set to small areas S _K over the same width in the two images to be synthesized across the boundary, further, natural boundary portion It can be formed as a perfect image. As a result, the synthesized image can be made more natural and free from discomfort, and the image quality can be further improved.

(Effects) According to the present invention, it is possible to naturally connect two images based on the image data subjected to the binarization processing, and to create a combined image without a sense of discomfort. Therefore, the capacity of the image memory can be reduced, the price of the device that performs image synthesis can be reduced, and the image quality of the synthesized image can be improved.

[Brief description of the drawings]

1 to 6 are diagrams showing an embodiment of the image synthesizing system according to the first aspect of the present invention. FIG. 1 is a functional block diagram of an image processing apparatus to which the image synthesizing system is applied, and FIG. Is a format of the dither matrix, FIG. 3 is a schematic diagram of an image to be synthesized, FIG. 4 is an operation explanatory view showing a procedure of setting a new image in an overlapping portion of the image, and FIG. FIG. 6 is a schematic diagram showing division of a small area of a part, and FIG. 6 shows a dither matrix format corresponding to the small area of an overlapping part of an image. 7 to 9 show an embodiment of the image synthesizing method according to the second aspect of the present invention. FIG. 7 is a functional block diagram of an image processing apparatus to which the image synthesizing method is applied. FIG. 9 is a schematic diagram of an image to be synthesized, and FIG. 9 is an operation explanatory view showing a procedure of a setting process of a new image at a boundary portion of the synthesized image. FIG. 10 is a diagram showing another embodiment of the image synthesizing method according to the second aspect of the present invention, and is an operation explanatory diagram showing a procedure for setting a new image at a boundary portion of the synthesized image. 1, 11 image processing device, 2, 3 dither processing circuit, 4, 5 image memory, 6, 12 synthesis processing circuit, 7 image memory, Sp, Sa, Sb, S _K ... ... Small area, P ... Duplicate part, DM ... Dither matrix.

Claims (2)

(57) [Claims] An image synthesizing method for synthesizing two types of images obtained by binarizing multi-valued data using the same m.times.n dither matrix. The arrangement in each area of the dither matrix used for the binarization of the value data is synthesized at a position that is continuous at a boundary position between the two images, and both images are m-scanned in the main scanning direction at the boundary portion.
A predetermined number of pixels and a predetermined number of n pixels are overlapped in the sub-scanning direction, and the overlapped portion is divided into m × n small regions. The number of black pixels or white pixels is detected, and the detection result and
A new black pixel number and a white pixel number of the small area are set based on the position of the small area in the overlapping portion, and a new black pixel in the small area is set based on the m × n dither matrix. An image synthesis method characterized by setting the positions of pixels and white pixels. 2. An image synthesizing method for synthesizing two types of images obtained by binarizing multi-valued data using the same m.times.n dither matrix. The arrangement in each area of the dither matrix used for the binarization of the value data is synthesized at a continuous position at the boundary position between the two images, and the boundary portion includes the pixels of both images, m pixels in the main scanning direction, and the sub-scanning. A small area of n pixels is set in the direction, the number of black pixels or white pixels in the small area is detected, and a new arrangement of the detected number of black pixels and white pixels is associated with the small area. An image synthesis method characterized by setting based on a × n dither matrix.