JP2001111820A - Image magnification device and image magnification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize memory reduction and high-speed processing in the case of magnifying an input image twice or over. SOLUTION: Magnification circuits are placed in series so that a magnification result of a pre-stage magnification circuit 201 is an input to a post-stage magnification circuit 202, a same pixel is repetitively given to the head magnification circuit 201 by number of times in response to the magnification in the main scanning direction, number of pixel in response to the magnification of the last magnification circuits 202, 203 is extracted as a magnified pixel from the magnification result outputted from the last magnification circuits 202, 203 and every time the same pixel is received, the extracted position of the pixel is sequentially shifted in the main scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for digital data such as a facsimile, a scanner, a digital copy, etc., and more particularly to an image scaling processing apparatus for enlarging or reducing an image including characters and line drawings at an arbitrary magnification. Related to the zooming method.

[0002]

2. Description of the Related Art In a conventional image scaling processing apparatus having a function of enlarging and reducing a binarized image, for example, as disclosed in JP-A-6-164896 or JP-A-6-253140, At the time of reduction, the thinning-out process is performed at intervals according to the reduction ratio. At the time of enlargement, the integral thinning-out is performed, and then the thinning-out process according to the expansion ratio is performed by the same processing as the reduction. Thus, enlargement / reduction processing at an arbitrary magnification is performed. In addition, 4 in the main scanning direction and the sub-scanning direction.
When performing the double enlargement, an image enlarged twice by the smoothing process is generated, and the output twice enlarged image is input again, and the image data enlarged four times is obtained through the same circuit.

[0003]

However, in the above-mentioned prior art configuration, when the input image is enlarged twice or more in the main scanning direction and the sub-scanning direction, the image enlarged twice is enlarged again and enlarged. The image was generated, but in this enlargement method
A memory for storing the image after double magnification was required.

[0004] The smoothing process is an excellent method in that an enlarged image with reduced unevenness can be obtained, but the amount of data to be processed tends to be large because of the pattern matching process. In particular, when the enlargement ratio becomes twice or more and the enlargement by the smoothing process is repeated, there is a problem that the amount of data to be handled increases and the processing time becomes longer.

As an enlargement method, a simple enlargement method is known in addition to the smoothing process. The simple enlargement method is a method in which the amount of data to be handled is reduced as compared with the smoothing processing by viewing only the three corner pixels adjacent to the target pixel. However, depending on the pixel change pattern, mutual changes interfere with each other, and the original smoothness is obtained. However, there is a problem that irregularities are formed although the purpose should be

[0006] In the case of the processing of 2 times or less such as 1.5 times in the enlargement processing, the normal output 2 × 2 pixels are simply thinned out to form (2 × 1) pixels or (1 × 2) pixels. However, in the case of simple thinning, the smoothness of the black and white boundary line is lost, and the image quality tends to deteriorate.

In the reduction processing, the input image is simply thinned out or OR thinned out, but this has a high possibility of deteriorating the image quality. For example, isolated points and notches remain, thin lines are interrupted by simple thinning,
In some cases, when black pixels were thinned out by R thinning out, black loss occurred.

In the reduction processing, overwriting is performed for thinning-out processing. There are three types of reduction processing in the main scanning direction, reduction processing in the sub-scanning direction, and reduction processing in both the main and sub directions depending on the direction in which the overwriting is performed. However, there has been a problem that the circuit scale becomes large because the reduction processing of is performed by separate circuits.

Further, when performing the reduction processing, a plurality of input pixels are output to the same output address, and the image area separation result of each input pixel is not always the same. The result of image area separation is very important in outputting final image data. Heretofore, the image area separation data of a pixel finally effective by simple thinning or OR thinning has been used as the image area separation result of the output pixel. However, in such a method, since data that is thinned out at random is used, a halftone determination result remains in an image with many characters, or a character determination result in an image with many halftones is obtained. The result of the judgment was that the image was left and did not match the input image.

The present invention has been made in view of the above point. First, it is possible to reduce the memory and increase the processing speed in enlarging an input image by a factor of two or more. Thirdly, a smooth image with few irregularities can be obtained when magnifying an image at an arbitrary magnification, and thirdly, when reducing the image data at an arbitrary magnification, the image magnification can be prevented from being deteriorated due to simple thinning or OR thinning. It is an object to provide a processing device and an image scaling processing method.

[0011]

According to the present invention, the same pixel is repeatedly input to the leading enlargement circuit arranged in series by the number of times corresponding to the magnification in the main scanning direction or the sub-scanning direction, and the enlargement circuit of the preceding stage is inputted. The output is input to the subsequent enlargement circuit, and the number of pixels corresponding to the enlargement ratio of the last enlargement circuit is extracted as enlarged pixels from the enlargement result output by the last enlargement circuit, and each time the same pixel is input, the pixel is extracted By sequentially shifting the position in the main scanning direction or the sub-scanning direction, an enlargement of 4 times or more is realized without having an external memory.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is an image scaling device in which a plurality of enlargement circuits are arranged in series so that the enlargement result of the enlargement circuit of the preceding stage is input to the enlargement circuit of the subsequent stage. The same pixel is repeatedly input to the first enlargement circuit by the number of times corresponding to the magnification in the main scanning direction, and the number of pixels corresponding to the enlargement ratio of the last enlargement circuit is enlarged from the enlargement result output by the last enlargement circuit. An image magnification changing apparatus characterized in that pixels are taken out as pixels, and each time the same pixel is inputted, the taken out position of the pixels is sequentially shifted in the main scanning direction.

According to a second aspect of the present invention, there is provided an image scaling device in which a plurality of enlargement circuits are arranged in series such that an enlargement result of a former enlargement circuit is input to a latter enlargement circuit. The same pixel is repeatedly input to the circuit by the number of times according to the magnification in the sub-scanning direction, and the number of pixels corresponding to the enlargement ratio of the last enlargement circuit is extracted as an enlargement pixel from the enlargement result output by the last enlargement circuit, An image scaling device characterized by sequentially shifting a pixel extraction position in the sub-scanning direction each time the same pixel is input.

According to the image scaling device of the first and second aspects,
A plurality of enlargement circuits are arranged in series so that the enlargement result of the former enlargement circuit becomes the input of the latter enlargement circuit, and the same enlargement circuit is provided in the first enlargement circuit by the number of times corresponding to the magnification in the main scanning direction or the sub-scanning direction. While the input is repeated only, enlarged pixels are extracted for each input from the enlarged result output from the last enlarging circuit, so that it is not necessary to have a memory for storing the enlarged result once enlarged for the next enlargement.

According to a third aspect of the present invention, N
The peripheral pixels of N × N pixels are compared with the reference patterns of N × N pixels, and M corresponding to the reference pattern having a high degree of coincidence with the input image is obtained.
A smoothing enlargement processing circuit that outputs a pixel pattern of × M pixels as an enlargement result, and replaces the pixel corresponding to the corner with the same data as the plurality of pixels at the corner if the plurality of pixels at the corner adjacent to the target pixel are the same data By performing the same replacement for each corner centered on the target pixel, M
A simple enlargement processing circuit that generates a pixel pattern of × M pixels, and a simple enlargement processing circuit that simply repeats the same data as the pixel of interest to generate a pixel pattern of M × M pixels, An image scaling device, characterized in that a simple enlargement processing circuit and a simple enlargement processing circuit are configured to be switchable, and a simple enlargement process is performed as the magnification increases.

According to this image scaling device, there are provided a smoothing enlargement processing circuit whose processing is complicated, a simple enlargement processing circuit whose processing is simple, and a simple enlargement processing circuit whose processing complexity is intermediate between the two. Since a simple enlargement process is performed as the magnification increases, a delay in processing time caused by performing a complicated enlargement process at a large magnification can be prevented, and deterioration of image quality at a small magnification can be prevented. .

According to a fourth aspect of the present invention, in the image scaling device of the third aspect, the smoothing enlargement processing circuit, the simple enlargement processing circuit, and the simple enlargement processing circuit are used in combination according to an enlargement ratio. .

As a result, it is possible to perform the scaling process while suppressing the deterioration of the image quality and the delay of the processing time.

According to a fifth aspect of the present invention, if three pixels at a corner adjacent to a pixel of interest have the same data, and at least one pixel of a color different from the pixel of interest is included in a peripheral pixel near the corner. , A pixel corresponding to the corner is replaced with the same data as the three pixels of the corner, and the same replacement is performed for each corner centered on the pixel of interest, thereby generating a pixel pattern of M × M pixels. is there.

According to this image scaling device, in addition to the three pixels at the corner adjacent to the pixel of interest, the color of the output pixel is determined by referring to the peripheral pixels near the corner. Places that are uneven due to interference can also be made gentle.

According to a sixth aspect of the present invention, a block of N × N pixels obtained by enlarging a target pixel is divided into N × 1 pixels or 1 × N pixels.
When superimposing pixels in order to replace them with N pixels, an image transformation characterized by storing and superimposing white pixels or black pixels so as to smooth a boundary line with reference to peripheral pixels of a target pixel. It is a doubling device.

According to this image scaling device, when a block of N × N pixels is replaced with N × 1 pixels or 1 × N pixels, the boundary line is smoothed with reference to the peripheral pixels of the target pixel. Since the white pixels or the black pixels are stored and superimposed, it is possible to obtain an image whose boundary line is smoothed.

According to a seventh aspect of the present invention, there is provided an image processing circuit for removing at least one of an isolated point and a notch from an input image, and a reduction process for the input image from which the isolated point or the notch has been removed by the image processing circuit. And a reduction processing circuit for performing the following.

According to this image scaling device, since the isolated points or notches are removed from the input image before the reduction processing, it is possible to prevent the image quality from deteriorating due to the isolated points or notches remaining in the reduced image.

According to an eighth aspect of the present invention, there is provided a thin line determination circuit for comparing a peripheral pixel including a target pixel with a reference pattern to determine whether or not the target pixel is a fine line, and determining a pixel in a main scanning direction or a sub-scanning direction. An image scaling device comprising: a reduction processing circuit that determines a white pixel or a black pixel by referring to a thin line determination result of the thin line determination circuit when performing an overlapping reduction process.

According to this image scaling device, when executing a reduction process of superimposing pixels in the main scanning direction or the sub-scanning direction, a white pixel or a black pixel is determined with reference to a thin line determination result. It is possible to prevent darkening and blackening.

According to a ninth aspect of the present invention, in the image scaling device according to the eighth aspect, the thin line determination circuit determines whether the target pixel is a black thin line, a white thin line, or a white thin line by comparing a peripheral pixel with a reference pattern. It shall be determined whether it is a candidate or other.

According to this image scaling device, white thin line candidates are determined in addition to black thin lines and white thin lines in thin line determination.
It is possible to obtain a reduced image in which white thin lines are effectively stored.

According to a tenth aspect of the present invention, when it is determined whether a target pixel is a thin line by comparing peripheral pixels including the target pixel with a reference pattern, a thin line is detected based on the thin line width and continuity. A thin line determination circuit characterized by using a reference pattern.

According to this thin line determination circuit, a thin line is detected based on the thin line width and continuity, so that the number of reference patterns can be greatly reduced and the processing time can be shortened.

According to an eleventh aspect of the present invention, there is provided a main scanning direction reduction processing circuit for reducing a pixel group to be reduced by superimposing pixels in the main scanning direction, and a current output from the main scanning direction reduction processing circuit. An image scaling device includes a sub-scanning direction reduction processing circuit that superimposes a reduction result of a line and a reduction result in a sub-scanning direction up to a previous line.

According to this image scaling device, since the reduction processing in the main scanning direction and the reduction processing in the sub-scanning direction are separately executed, the reduction processing circuit in the main scanning direction and the reduction processing circuit in the sub-scanning direction correspond. And the circuit scale can be reduced.

A twelfth aspect of the present invention is an image scaling device for switching between character image processing and halftone image processing using an image area separation result, and determines the image area separation result of an output pixel. The following functions (1) to (6) are provided as functions: (1) All image area separation results of output pixels are converted into characters (2) Even if only one pixel is included in a pixel group to be reduced, the image area separation result of characters is output Is included, the image area separation result of the output pixel is defined. (3) If at least one pixel is included in the group of pixels to be reduced, the image area of the output pixel is included. Make the separation result halftone. (4) Make all the image area separation results of the output pixels halftone. (5) Make the image area separation results of the pixels effective as a result of the reduction processing the image area separation results of the output pixels. (6) Image area separation and formation of each pixel targeted for reduction An image scaling apparatus which can select any of the above (1) to (6), image area separation result of the output pixel largest number of image area separation result of the.

According to this image scaling device, the operator can select the optimum judgment mode according to the input image, so that the image quality can be improved.

According to a thirteenth aspect of the present invention, the same pixel is repeatedly input to the leading enlargement circuit arranged in series by the number of times corresponding to the magnification in the main scanning direction or the sub-scanning direction, and the output of the preceding enlargement circuit is provided. Is input to the subsequent enlargement circuit, and the number of pixels corresponding to the enlargement ratio of the last enlargement circuit is extracted as an enlargement pixel from the enlargement result output by the last enlargement circuit, and each time the same pixel is input, the extraction position of the pixel is extracted. Is sequentially shifted in the main scanning direction or the sub-scanning direction.

A fourteenth aspect of the present invention provides a smoothing enlargement processing circuit for enlarging a target pixel by smoothing processing, a simple enlargement processing circuit for enlarging a target pixel by simple enlargement processing, and a simple enlargement for enlarging a target pixel by simple enlargement processing. This is an image scaling method characterized in that the processing circuit is switched so as to perform simple enlargement processing as the magnification increases.

According to a fifteenth aspect of the present invention, a smoothing enlargement processing circuit for enlarging a target pixel by smoothing processing, a simple enlargement processing circuit for enlarging a target pixel by simple enlargement processing, and a simple enlargement for enlarging a target pixel by simple enlargement processing This is an image scaling method characterized in that the processing circuit performs enlargement processing by changing the combination in accordance with the enlargement ratio.

In a sixteenth aspect of the present invention, if three pixels at a corner adjacent to a pixel of interest have the same data and at least one pixel of a color different from the pixel of interest is included in a peripheral pixel near the corner. , A pixel corresponding to the corner is replaced with the same data as the three pixels at the corner, and the same replacement is performed for each corner around the pixel of interest, thereby generating a pixel pattern of M × M pixels. is there.

According to a seventeenth aspect of the present invention, a block of N × N pixels obtained by enlarging a pixel of interest is divided into N × 1 pixels or 1 block.
When superimposing pixels in order to replace them with × N pixels, an image characterized by storing and superimposing white pixels or black pixels so that a boundary line is smoothed with reference to peripheral pixels of a target pixel. This is a scaling method.

An eighteenth aspect of the present invention is an image scaling method characterized in that at least one of an isolated point and a notch is removed from an input image, and thereafter a reduction process is performed on the input image.

According to a nineteenth aspect of the present invention, a reduction process is performed in which peripheral pixels including a target pixel are compared with a reference pattern to determine whether the target pixel is a thin line, and pixels are overlapped in the main scanning direction or the sub-scanning direction. An image scaling method, wherein a white pixel or a black pixel is determined with reference to the thin line determination result at the time of execution.

According to a twentieth aspect of the present invention, when it is determined whether a target pixel is a thin line by comparing peripheral pixels including the target pixel with a reference pattern, a thin line is detected based on the thin line width and continuity. This is a thin line determination method characterized by using a reference pattern.

According to a twenty-first aspect of the present invention, a reduction process in the main scanning direction is performed by superimposing pixels in the main scanning direction on a group of pixels to be reduced, and the result of the reduction of the current line and the sub-scanning to the previous line are performed. An image scaling method characterized in that a reduction process in the sub-scanning direction is executed by superimposing the reduction result in the direction.

A twenty-second aspect of the present invention is an image scaling method for switching between character image processing and halftone image processing using the image area separation result, and determines the image area separation result of output pixels. The following methods (1) to (6) are provided: (1) All image area separation results of output pixels are converted to characters (2) Image area separation results of characters even if only one pixel is included in the pixel group to be reduced Is included, the image area separation result of the output pixel is defined. (3) If at least one pixel is included in the group of pixels to be reduced, the image area of the output pixel is included. Make the separation result halftone. (4) Make all the image area separation results of the output pixels halftone. (5) Make the image area separation results of the pixels effective as a result of the reduction processing the image area separation results of the output pixels. (6) Image area separation and formation of each pixel targeted for reduction It is most numerous image area separation result of the above, and image area separation result of the output pixel (1) image scaling method for selecting one of - (6) of the.

Hereinafter, an image scaling processing apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a functional block diagram of the image scaling device according to the present embodiment. An input pixel signal of a digital image (hereinafter, referred to as image data) is stored in an image memory 10.
1 temporarily. The image area separation circuit 102, the character scaling circuit 103, and the projection processing circuit 104
From 01, image data necessary for each process is read and used.

The image area separation circuit 102 is a part for determining the character or halftone for the pixel of interest. The character scaling circuit 103 is a part that executes enlargement processing and reduction processing suitable for characters. The projection processing circuit 104 is a part that executes enlargement processing and reduction processing suitable for halftone.

The magnification (MX) in the main scanning direction and the magnification (MY) in the sub-scanning direction are given to a magnification counter operation circuit 105. The magnification counter arithmetic circuit 105 calculates a combination of enlargement and reduction processing from the main scanning direction magnification (MX) and the sub-scanning direction magnification (MY). For example, when the magnification is 4 times in the main scanning direction and the sub-scanning direction, if the magnification is 2 × 2 in one enlargement process, the image is decomposed into a combination of 2 × 2 and 2 × 2. In the case of triple, 2 × 2 and 1.
Decompose into 5-fold combinations. Magnification counter operation circuit 1
The magnification data and the data for calculating the output address output from the control circuit 105 are supplied to the control circuit 106. The control circuit 106 calculates the output address and calculates the image area separation circuit 1
02, output to the character scaling circuit 103 and the projection processing circuit 104.

Character scaling circuit 103 and projection processing circuit 10
The scaled data generated in parallel in step 4 is the image signal synthesis circuit 1
07. The image signal synthesizing circuit 107 selectively outputs the output of the character scaling circuit 103 when the discrimination signal from the image area separation circuit 102 is a character discrimination result, and outputs the output of the projection processing circuit 104 when the discrimination signal is a halftone discrimination result. Select and output the output.

The scaled image data selected by the image signal synthesizing circuit 107 is subjected to error diffusion processing by an error diffusion circuit 108 and then input to a black and white compulsory circuit 109. The black-and-white forcing circuit 109 corrects the value to 0 when the multi-value input value before error diffusion processing is the minimum value, and corrects it to 1 when the value is the maximum value. This can prevent the resolution of the mixed character image from being reduced.

The character scaling circuit 103 includes an enlargement processing section 111 for enlarging an input image and a reduction processing section 1 for reducing an input image.
12 are provided. Hereinafter, the processing contents of the enlargement processing unit 111 and the reduction processing unit 112 will be described in detail.

FIG. 2 is a functional block diagram of the enlargement processing section 111 in the character scaling circuit 103. Enlargement processing unit 11
1 includes a smoothing enlargement processing circuit 201, a simple enlargement processing circuit 202, and a simple enlargement processing circuit 203.
Each of the three enlargement circuits executes a double enlargement process and outputs 2 × 2 pixels for the target pixel.

The smoothing expansion processing circuit 201 has 5 ×
A pattern storage unit is provided in which a pixel arrangement pattern of five pixels and a pixel arrangement pattern of 2 × 2 pixels are associated. FIG.
2 shows a pixel arrangement pattern of 2 × 2 pixels. The smoothing enlargement processing circuit 201 reads out the image data of 5 × 5 pixels centering on the pixel of interest from the image memory 101 and sequentially compares the image data with the pixel pattern of 5 × 5 pixels in the pattern storage unit.
A pixel layout pattern of 2 × 2 pixels corresponding to a pixel pattern that matches the image data of 5 × 5 pixels is selected as a 2 × enlarged pixel.

The simple enlargement processing circuit 202 includes a pattern storage unit in which a 3 × 3 pixel pattern and a 2 × 2 pixel arrangement pattern are associated. FIG. 6 shows the relationship between the pixel arrangement pattern of 3 × 3 pixels and the pixel pattern of 2 × 2 pixels. Details of the simple enlargement process in the simple enlargement processing circuit 202 will be described later. By referring to the 3 × 3 pixels around the target pixel, a pixel arrangement pattern of 2 × 2 pixels, which is a result of doubling the target pixel, is output.

The simple enlargement processing circuit 203 simply doubles the target pixel in the main scanning direction and the sub-scanning direction,
A pixel pattern of × 2 pixels is output.

The output stage of the smoothing processing unit 201 is the first
And to the input stage of the simple enlargement processing unit 202. The output stage of the simple enlargement processing unit 202 is connected to the input stage of the second enlarged data creation unit 205 and to the input stage of the simple enlargement processing unit 203. Simple enlargement processing unit 2
The output stage 03 is connected to the input stage of the third enlarged data creation unit 206.

First to third enlarged data creating units 204 and 2
06 indicates that the enlarged pixel of one target pixel is 2 × 1 pixel or 1 × 2.
This is the part that creates these data when it is a pixel. Although details of the processing here will be described later, 2 × 2 pixels obtained by the 2 × enlargement processing unit are superimposed in the main scanning direction or the sub-scanning direction to produce 2 × 1 pixels or 1 × 2 pixels. ing.

The output image data selection section 207 is a section for selecting output image data according to the output address given from the control circuit 106. The image data at the output address specified by the control circuit 106 is selected and output to the image signal synthesizing circuit 107.

The enlargement processing unit 111 configured as described above
In this case, the smoothing processing unit 201 is used until the magnification is doubled.
02, and the simple enlargement processing unit 203 is used for enlargement exceeding 4 times to 8 times.

In the case of double magnification, the smoothing processing unit 2
The target pixel is converted into 2 × 2 pixels by using 01, and is input to the output image data selection unit 207 through the first enlarged data generation unit 204. In the case of double enlargement, the output data of the smoothing processing unit 201 is used. Therefore, the output image data selection unit 207 selects and outputs the input image data by passing through the enlargement data creation unit 204 according to the output address.

FIG. 4 is a conceptual diagram showing a case where the image is enlarged four times in the main scanning direction. The smoothing processing unit 201 takes in the input pixel A and enlarges it twice (first input). When the smoothing processing unit 201 outputs image data of 2 × 2 pixels, the simple enlargement processing unit 202 performs (A-1)
Pixels are fetched from the smoothing processing unit 201 and doubled by simple enlargement processing to obtain 2 × 2 pixel image data (A-1).
1, A-12, A-13, and A-14). The control circuit 106 controls an output address so that A-11 and A-12 are output as valid pixels. If the number of output lines is one, other data is discarded.

The smoothing processing unit 201 returns to the pixel A
And take it up twice (input second time). The smoothing processing unit 201 outputs image data of 2 × 2 pixels.
The simple enlargement processing unit 202 simply enlarges the (A-2) pixel. The simple enlargement processing unit 202 outputs the second (A) in the main scanning direction.
-2) Image data of 2 × 2 pixels by doubling the pixel (A-2)
1, A-22, A-23, A-24)
The control circuit 106 controls an output address so that A-21 and A-22 are output as valid pixels. If the number of output lines is one, other data is discarded.

As a result, pixel data obtained by quadrupling the pixel A in the main scanning direction from the enlargement processing section 111 is output as effective pixels.

When the magnification in the sub-scanning direction is greater than 2 times, A-1 and A-2 are processed at the first time, and B-1 and B-
2, after one line is completed, the same line is input again and processed as A-1, A-2, B-1, and B-2, and the outputs are A-13, A-14, A -23, A-24 ...
Becomes When processing for one line is completed, the same line is input again and processed as A-3, A-4, B-3, and B-4, and outputs are A-31, A-32, A-41, and A-31. -42 ...
Becomes When the processing for one line is completed, the same line is input again and processed as A-3, A-4, B-3, and B-4, and the output is A-33, A-34, A-43, A -44 ...
Becomes

This means that the enlargement in the sub-scanning direction has been performed.

The other pixels are processed similarly in order. As a result, from the simple enlargement processing unit 202, one pixel of interest fetched from the image memory 101 is magnified 4 times to 4 ×
4 is output. The quadruple-magnification image data output from the simple enlargement processing unit 202 passes through the second enlargement data creation unit 205 and is input to the output image data selection unit 207. In the case of quadruple enlargement, the output data of the simple enlargement processing unit 202 is used, so the output image data selection unit 207 selects and outputs the input image data by passing through the second enlargement data creation unit 205 according to the output address.

In the case of 8 times magnification, the smoothing processing unit 2
01 and the simple enlargement processing unit 202 further enlarges the image by two times.
The 4 × 4 pixel image data that has been enlarged twice is directly input to the simple enlargement processing unit 203. The simple enlargement processing unit 203 takes in the image data of 4 × 4 pixels enlarged by 4 times from the simple enlargement processing unit 202 for each pixel, and enlarges the image data twice by simple enlargement processing. As a result, the simple enlargement processing unit 203
From the target pixel fetched from the image memory 101
8 × 8 image data that is doubled is output. The 8-fold enlarged image data output from the simple enlargement processing unit 203 is the third
Is input to the output image data selection unit 207 through the enlarged data creation unit 206. In the case of 8-fold enlargement, since the output data of the simple enlargement processing unit 203 is used, the output image data selection unit 207 selects and outputs the input image data by passing through the third enlargement data creation unit 206 according to the output address.

As described above, the enlargement circuit (smoothing processing section 201, simple enlargement processing section 202 and simple enlargement processing section 203) of the double enlargement is arranged in multiple stages, and in the case of the double enlargement, the first stage smoothing processing section 201 is provided. Inputs the input pixel A once and generates a double-magnified image by enlarging the input pixel A twice, and in the case of quadruple-magnification, the simple enlarging processing unit 202 outputs the double image data of the input pixel A from the preceding smoothing processing unit 201. Are input two times (one line) one pixel at a time, and are respectively enlarged twice to generate a four-fold enlarged image of the input pixel A. In the case of eight-fold enlargement, the simple enlargement processing unit 203 From 202, quadruple image data is input four times (for one line) one pixel at a time, and each is doubled to generate an eightfold enlarged image of the input pixel A.

Thus, in the case of performing enlargement processing larger than two times, the output from the character scaling circuit 103 is stored in the image memory every time the magnification is doubled, which is conventionally performed, and is input to the character scaling circuit 103 again. Since the process of redoing the image data is eliminated, the memory for using the enlarged image data in the character scaling circuit again can be reduced.

The smoothing process executed by the smoothing processing unit 201 has an excellent effect on improving the image quality of an enlarged image, but when the enlargement magnification is increased, the amount of data to be handled is increased and the processing time tends to be longer. . On the other hand, the simple enlargement processing executed by the simple enlargement processing unit 203 has an advantage that the processing time is reduced because the processing is simple even when the enlargement magnification is large, but the image quality tends to be conspicuous when the enlargement magnification is large. . The simple enlargement processing executed by the simple enlargement processing unit 202 is located between the two. Regarding the circuit scale required for the enlargement processing, the smoothing processing unit 201 is the largest, the simple enlargement processing unit 202 is the second largest, and the simple enlargement processing unit 203 is the smallest.

In the present embodiment, the above-mentioned circuit arrangement is adopted in consideration of the amount of data handled and the circuit scale of the above three types of enlargement methods, so that the processing speed does not become slow even if the enlargement ratio becomes large. In addition, even if the enlargement ratio becomes large, the deterioration of the image quality can be suppressed to some extent. That is, the enlargement processing circuit used in accordance with the magnification M is determined as follows.

When 1 <M ≦ 2, smoothing processing 2 <M ≦ 4, smoothing processing (2 times) + simple enlargement processing (2 times or less) 4 <M ≦ 8, smoothing processing ( (2 ×) + simple enlargement processing (2 ×) + simple enlargement processing (2 × or less) As described above, in the range where the enlargement ratio up to 2 × enlargement is small, a high-quality enlarged image is generated by smoothing processing. In the range where the enlargement ratio is relatively large from 2 times enlargement to 4 times enlargement, by combining smoothing processing and simple enlargement processing, the processing time is shortened as compared with the case where the smoothing processing is repeated twice, and simple enlargement processing or simple enlargement is performed. It is intended to obtain higher image quality than using only processing. Further, in a large range of the enlargement ratio from 4 × to 8 ×, up to 4 × is combined with the smoothing processing and the simple enlargement processing to suppress the deterioration of the image quality. Let's use the simple enlargement procedure. As described above, by switching the content of the enlargement processing to simple processing as the enlargement ratio increases, the deterioration of the image quality is suppressed, the processing time is reduced, and the enlargement of the circuit scale is also suppressed.

The above three enlargement processing units 201 to 20
In No. 3, a loop for repetition is formed so that the same enlargement process can be repeated. A mode in which the processing speed is prioritized can be selected. When the mode in which the processing speed is prioritized is selected, the simple enlargement processing unit 203 fetches the input pixels from the image memory 101 regardless of the enlargement magnification, and Is returned to the simple enlargement processing unit 203 for the number of times corresponding to the simple enlargement processing. Conversely, the mode in which the image quality is prioritized can be selected. When the mode in which the image quality is prioritized is selected, the smoothing processing unit 201 fetches the input pixels from the image memory 101 regardless of the enlargement ratio, and Is returned to the smoothing processing unit 201 by the number of times corresponding to the above, and the smoothing enlargement processing is performed. Further, the mode for looping may be selected by the simple enlargement processing unit 202 alone.

Next, pattern matching in the simple enlargement processing section 202 will be described in detail. Simple enlargement processing unit 2
No. 02 simply enlarges the target pixel of one pixel to 2 × 2 pixels using the reference patterns shown in FIGS. 6 (a) to 6 (e). In the present embodiment, the pixel around the target pixel 3
× 3 pixels are referenced.

The upper left pixel in the 2 × 2 pixels after the simple enlargement is determined by the pattern shown in FIG. That is, among the 3 × 3 pixels centered on the pixel of interest, if all three pixels in the upper left corner have the same color and a different color from the pixel of interest, the pixel in the upper left corner of 2 × 2 pixels is Corner 3
Make the same color as the pixel. Specifically, when the pixel of interest is black and the three pixels at the upper left corner are white, the pixels at the upper left corner of the 2 × 2 pixels simply enlarged become white.

The pattern shown in FIG. 6B determines the pixel at the upper right corner in 2 × 2 pixels after the simple enlargement. That is, among the 3 × 3 pixels centered on the target pixel, if the colors of the three pixels at the upper right corner are all the same and different from the pixel of interest, the pixel at the upper right corner of 2 × 2 pixels is The same color as the three pixels at the corner is used. Specifically, when the target pixel is black and the three pixels at the upper right corner are white, the pixels at the upper right corner of the 2 × 2 pixels simply enlarged become white.

The pattern shown in FIG. 6C determines the pixel at the lower left corner in 2 × 2 pixels after the simple enlargement. That is, of the 3 × 3 pixels centered on the target pixel, all three pixels at the lower left corner have the same color different from the target pixel, and even one of the four pixels indicated by oblique lines has a different color from the target pixel. Then, the pixel at the lower left corner of 2 × 2 pixels is made the same color as the three pixels at the lower left corner.

The pattern shown in FIG. 6D determines the pixel at the lower right corner in 2 × 2 pixels after the simple enlargement. That is, among the 3 × 3 pixels centered on the target pixel, all three pixels at the lower right corner have the same color different from the target pixel, and even one of the four pixels indicated by oblique lines has a different color from the target pixel. Then, the pixel at the lower right corner of 2 × 2 pixels is made the same color as the three pixels at the lower right corner.

The pattern shown in FIG. 6E indicates that 2 × 2 pixels of the same color as the pixel of interest are output when eight pixels around the pixel of interest are unrelated to pattern matching. It is used when the target pixel is not the specified pattern, such as when it is the first pixel of the input image.

FIG. 7 shows a processing result obtained by comparing the result of simple enlargement by the present method using the above reference pattern (FIG. 7B) with the result of simple enlargement by the conventional method (FIG. 7C). Show. In the conventional simple enlargement method, the unevenness of the boundary line between the white pixel and the black pixel greatly changes. However, in the simple enlargement method of the present embodiment, an image in which the unevenness of the boundary line is reduced is obtained.

In the present embodiment, in order to determine the 2 × 2 pixels after the simple enlargement, not only the pattern of each of the three pixels at the four corners as in the conventional simple enlargement is viewed, but also the patterns shown in FIGS. ), The reference area has been extended to the shaded area. As a result, it is possible to obtain an image in which unevenness caused by interference between the changes is reduced, and to shorten the processing time because the enlargement processing is performed under a condition that is significantly less than the pattern matching of the smoothing processing. it can.

Next, the fraction processing in the enlarged data creation units 204 to 206 will be described in detail. Since each of the enlarged data creation units 204 to 206 performs the same fractional processing, the enlarged data creation unit 204 will be described here as an example.

As described above, since the three processing units 201 to 203 in the enlargement processing unit 111 use double enlargement as a processing unit, 1.5 times, 3 times, etc., 2 N times (N is an integer) If the enlargement ratio is other than 2 × 2 pixels, 1 × 2
Fractional processing for conversion into pixels, 2 × 1 pixels or 1 pixel is required.

FIG. 8 is a conceptual diagram when an output image of 3 × 3 pixels is output by multiplying 2 × 2 pixels of the original image by 1.5. According to the output address, pixel A is 2 × 2 pixels, pixel B is 2 × 1 pixels, pixel C is 1 × 2 pixels, and pixel D is 1 × 2 pixels.
Each pixel is converted to one pixel to form an output image of 3 × 3 pixels.

First, the smoothing processing unit 201 reads the pixels A and B on the first line and the pixels C and D on the second line from the image memory 101, and performs smoothing processing on each of the pixels A, B, C and D by the smoothing process. Convert to × 2 pixels.

Since pixel A is 2 × 2 pixels in the output image, a00 and a0, which are the smoothing processing results, are obtained.
1, a10 and a11 are output as they are. The pixel D
Are 1 × 1 pixels in the output image, and thus 2 × 2 pixels (d00, d00,
d01, d10, d11) are superimposed on black or white, and output as one pixel. Note that if the pixel D is used as it is, the processing can be reduced.

Assuming that the 2 × 2 pixels obtained by the smoothing process are b00, b01, b10, and b11, the pixel B is converted into a 2 × 1 pixel by superimposing b00 and b01, and b10 and b11, respectively, and outputting. . In addition, pixel C
Converts c00 and c10 and c01 and c11 into 1 × 2 pixels by superimposing them, and outputs the result. Note that 00, 01
Are upper two pixels, and 10 and 11 are lower two pixels.

FIG. 9 shows a flow for converting 2 × 2 pixels obtained by the smoothing process into 2 × 1 pixels or 1 × 2 pixels. Processing branches depending on whether the target pixel is a black pixel or a white pixel. If the target pixel is a black pixel, the process branches depending on whether or not only one white pixel is included in 2 × 2 pixels of the smoothing result. If only one pixel contains a white pixel, the process proceeds to processing 1.

In this process 1, when superimposing pixels, it is determined whether or not it is in a state where superimposition of white priority should be performed with reference to pixels surrounding the target pixel. If the smoothing result is the pattern shown in FIG. 10A (only one pixel at the upper right or lower left is a white pixel = W), the upper left corner and the right corner of the 3 × 3 peripheral pixels are shaded in FIG. It is checked whether the lower corner pixels are both white pixels different from the target pixel. As a result of the check, if the state is as shown in FIG. 11, superimposition is performed with white priority, and otherwise, superimposition is performed with black priority. Therefore, for the pixel B in FIG. 8, if the above-described white priority condition is met, the 2 × 1 pixel shown in FIG.
Output the pixel. For the pixel C, if the white priority condition is met, a 1 × 2 pixel shown in FIG. 10C is output.

Also, the smoothing result is shown in the pattern shown in FIG. 12A (only one pixel at the upper left or lower right is a white pixel =
In the case of W), it is checked whether or not both the upper right corner and the lower left corner of the 3 × 3 peripheral pixels are white pixels different from the target pixel as shown by oblique lines in FIG. As a result of the check, if the state is as shown in FIG. 13, superimposition is performed with white priority, and otherwise, superposition is performed with black priority. Therefore, for the pixel B in FIG. 8, if the above-described white priority condition is met, the 2 × 1 pixel shown in FIG. 12B is output.
For the pixel C, if the above-described white priority condition is met, FIG.
2 (c) is output.

As described above, when the 2 × 2 pixels of the smoothing result are converted into 2 × 1 pixels or 1 × 2 pixels, only one pixel is different from the target pixel (black) for every 2 × 2 pixels of the smoothing result. If white) is included, two diagonal pixels sandwiching the pixel of interest are further checked, and if both are white, they are superimposed with priority on white, so that the smoothness of the image is not lost due to the fraction processing Can be.

A modified example of the processing 1 will be described with reference to FIGS. In the present modified example, if only one pixel (white) different from the target pixel (black) is included in 2 × 2 pixels of the smoothing result, black priority or white priority is referred to by referring to the peripheral pixels of the target pixel in the original image. Is determined and superimposed.

FIG. 14 shows a pattern for converting 2 × 2 pixels as a result of smoothing into 2 × 1 pixels. In the case shown in FIG. 11A, in the smoothing result, if only the upper left pixel is a white pixel different from the target pixel, the right and lower right of the target pixel in the original image are black pixels.
If the upper right pixel of the target pixel is a white pixel and at least one of the lower and lower left pixels is a white pixel, white pixels are superimposed. FIG.
In the case shown in (2), in the smoothing result, if only the upper right pixel is a white pixel different from the target pixel, the left and lower left of the target pixel are black pixels, and the upper left of the target pixel is a white pixel, and If at least one lower pixel is a white pixel, white pixels are superimposed. In the case shown in FIG. 3C, in the smoothing result, if only the lower left pixel is a white pixel different from the target pixel, the right and upper right of the target pixel are black pixels and the lower right of the target pixel is the original pixel in the original image. If at least one of the upper and upper left pixels is a white pixel, it is superimposed on white with priority. In the case shown in FIG. 11D, in the smoothing result, if only the lower right pixel is a white pixel different from the target pixel, the left and upper left of the target pixel in the original image are black pixels.
If the lower left pixel of the target pixel is a white pixel and at least one of the upper and upper right pixels is a white pixel, white pixels are superimposed.

FIG. 15 shows a pattern for converting 2 × 2 pixels as a result of smoothing into 1 × 2 pixels. In the case shown in FIG. 11A, in the smoothing result, if only the upper left pixel is a white pixel different from the target pixel, the lower and lower right pixels of the target pixel in the original image are black pixels.
If the lower left pixel of the target pixel is a white pixel and at least one of the right and upper right pixels is a white pixel, white pixels are superimposed. FIG.
In the smoothing result, if only the upper right pixel is a white pixel different from the target pixel, the lower and lower left of the target pixel in the original image are black pixels, and the lower right of the target pixel is a white pixel and If at least one upper left pixel is a white pixel, white pixels are superimposed. In the case shown in FIG. 11C, in the smoothing result, if only the lower left pixel is a white pixel different from the target pixel, the upper and upper right of the target pixel are black pixels and the upper left of the target pixel is white in the original image. If at least one of the right and lower right pixels is a white pixel, the pixels are superimposed in white priority. In the case shown in FIG. 4D, in the smoothing result, if only the lower right pixel is a white pixel different from the target pixel, the upper and upper left of the target pixel in the original image are black pixels, and the upper right of the target pixel is If at least one of the left and lower left pixels is a white pixel, the pixels are superimposed in white priority.

Even under the above-described superposition conditions, it is possible to prevent the smoothness of the image from being lost by the fraction processing.

On the other hand, in FIG. 9, when the target pixel is a black pixel, and as a result of the smoothing processing, if all of the 2 × 2 pixels are black pixels, the processing shifts to processing 2. In processing 2, 2 × 2 pixels of the smoothing result are superimposed in black priority to obtain 2 × 2 pixels.
Conversion to one pixel or 1 × 2 pixels.

When the target pixel is a white pixel, the smoothing result 2 is obtained by using a condition different from the above-described black pixel fraction processing.
2 × 1 pixels or 1 × 2 by superimposing × 2 pixels with black priority
Convert to pixels.

When the target pixel is a white pixel, the process branches depending on whether or not only one black pixel is included in 2 × 2 pixels as a result of the smoothing. If only one pixel contains a black pixel, the process proceeds to processing 3.

In the process 3, when superimposing pixels, it is determined whether or not it is in a state where superimposition with black priority is to be performed with reference to the peripheral pixels of the target pixel. At this time, 2 ×
Different conditions are added for one pixel and 1 × 2 pixels.

As a result of the smoothing process, if the pattern is as shown in FIG. 16A, the upper left and lower right pixels (the lower left hatched portion) centering on the target pixel in the original image shown in FIG. 17 are different from the target pixel. Check whether or not. Also,
If the pattern is as shown in FIG. 16B, it is checked whether the upper right pixel and the lower left pixel (the lower right hatched portion) around the target pixel in the original image shown in FIG. 17 are different from the target pixel.

As a result of the check, if the target peripheral pixel has a different color from the target pixel, different additional conditions are checked according to the pattern of the output image (the conversion result is 2 × 1 pixel or 1 × 2 pixel).

An additional condition for converting 2 × 2 pixels as a result of smoothing into 2 × 1 pixels will be described. FIG.
In the case of the smoothing result shown in FIG. 8A, if the left horizontal pixel of the target pixel in the original image (the pixel indicated by the diagonally slanted line to the left in FIG. 19) is a different color (black) from the target pixel, white superimposition is performed. A total of 2 × 1 pixels are output. It should be noted that if the color is the same as that of the pixel of interest, it is superimposed with black priority. FIG.
In the case of the smoothing result shown in (b), if the right horizontal pixel of the target pixel in the original image (the pixel indicated by the diagonally downwardly sloping line in FIG. 19) is a different color (black) from the target pixel, the black image is superimposed. To output 2 × 1 pixels. It should be noted that if the color is the same as that of the pixel of interest, it is superimposed with black priority.

An additional condition for converting 2 × 2 pixels as a result of smoothing into 1 × 2 pixels will be described. FIG.
In the case of the smoothing result shown in FIG. 0 (a), if the pixel immediately above the target pixel in the original image (the pixel indicated by the diagonally left-slanted line in FIG. 21) is a different color (black) from the target pixel, white-first overlapping A total of 1 × 2 pixels are output. It should be noted that if the color is the same as that of the pixel of interest, it is superimposed with black priority. FIG.
In the case of the smoothing result shown in (b), if the pixel immediately below the pixel of interest in the original image (the pixel indicated by the diagonally downwardly sloping line in FIG. 21) is a different color (black) from the pixel of interest, it is superimposed with black priority. Outputs 1 × 2 pixels. It should be noted that if the color is the same as that of the pixel of interest, it is superimposed with black priority.

When the pixel of interest is a white pixel, it is possible to prevent the smoothness of the output image from being lost by the above-described fraction processing.

On the other hand, in FIG. 9, when the target pixel is a white pixel, and as a result of the smoothing processing, if all of the 2 × 2 pixels are white pixels, the process shifts to processing 4. In processing 4, 2 × 2 pixels of the smoothing result are superimposed in white priority to obtain 2 × 2 pixels.
Conversion to one pixel or 1 × 2 pixels.

FIG. 22 is a functional block diagram of the reduction processing section 112 in the character scaling circuit 103. Reduction processing unit 1
Reference numeral 12 denotes a process for removing isolated points and notches from the input image before the reduction process. The isolated point notch removal processing unit 301 removes isolated points and notches by pattern matching. That is, a pixel pattern suitable for detecting an isolated point and a notch is prepared, and the input image and the pixel pattern are compared. If there is a target pixel that matches the pixel pattern of the isolated point or notch, it is converted to a pixel from which the isolated point or notch has been removed and output as an output pixel.

Conventionally, in the reduction processing of the OR thinning-out, black pixels have been overwritten with priority given to black pixels, so that isolated points and notches remain forever, deteriorating the image quality. In the method of the present embodiment, the isolated point and the notch are removed prior to the reduction processing, so that even if the black pixel is prioritized and the black pixel is overwritten, the isolated point and the notch do not remain, so that a high-quality image can be obtained. I can do it.

The reduction processing unit 112 removes isolated points and notches from the input image, and then performs thin line determination for each pixel of interest. The thin line determination unit 302 determines that the target pixel is a black thin line, a white thin line, a white thin line candidate,
Determine if the line is not thin.

FIGS. 23 to 25 show specific examples of reference patterns used by the thin line determination unit 302 for thin line determination. FIG.
Is a reference pattern for determining whether or not the target pixel is a fine black line. If the pattern matches the pattern shown in FIG. 7, it is determined that the target pixel is a fine black line. FIG. 24 shows a reference pattern for determining whether or not the pixel of interest is a thin white line. If the pattern matches the pattern shown in FIG. 24, it is determined that the pixel of interest is a thin white line. FIG. 25 shows a reference pattern for determining whether or not the pixel of interest is a thin white line candidate. If the pattern matches the pattern shown in FIG. 25, it is determined that the pixel of interest is a thin white line candidate. The reference pattern for detecting a white thin line candidate has relaxed conditions for white thin line determination compared to the reference pattern for detecting a white thin line.

In the present embodiment, the reference pattern used for thin line determination does not use the pattern of the line itself as the reference pattern, but determines whether or not the pixel of interest forms the width of the line. The pattern is such that it can be detected whether or not there is continuity in the vertical and horizontal directions with respect to the center.

As a result, lines can be recognized with as few reference patterns as 17 patterns, so that the amount of data processing for pattern matching can be greatly reduced and the processing time can be reduced. If the pattern of the line itself in the conventional method is used as a reference pattern, reference patterns corresponding to all angles must be prepared, so that a large number of line patterns are required, and the amount of data processing for pattern matching increases.

Next, the reduction processing section 112 performs reduction processing in the main scanning direction and reduction processing in the sub-scanning direction. In this reduction process, the pixels are superimposed such that the white thin line and the black thin line are preserved by using the thin line determination result.

The main scanning direction reduction processing section 303 executes reduction processing in the main scanning direction using the result of the thin line determination.
FIG. 26 shows rules when the main scanning direction reduction processing unit 303 superimposes pixels in the main scanning direction. In the figure,
“1” is a thin black line, “4” is a thin white line, “5” is a thin white line candidate, and “0” is a non-thin line. The hatched area in the figure is a part that cannot be used as a combination.

FIG. 26 (a) shows the priority when superposing the thin line information. The basic priority is in the order of black thin line> white thin line> white thin line candidate> black pixel> white pixel. For example, when the pixel of interest is a thin black line “1” and the previous pixel to be superimposed is a thin white line “4”, the thin black line “1” of the pixel of interest remains. When the target pixel is a non-fine line “0” and the previous pixel to be superimposed is a black thin line “1”,
A black thin line “1” of the previous pixel is left.

FIG. 26B shows the priorities for determining whether to leave white or black when the target pixel is a white pixel and the previous pixel to be superimposed is a black pixel. For example, when the pixel of interest is a white thin line “4” and the previous pixel to be superimposed is a non-fine line “0” of a black pixel, white is prioritized. Note 2 if the target pixel is the white thin line candidate “5” and the previous pixel to be superimposed is the black pixel non-fine line “0”. Note 2 is that if the pixel is the last pixel in the main scanning direction in the reduction target group and one pixel before the output pixel is a black pixel, the pixel is changed to a white pixel.

FIG. 26 (c) shows the priority in determining whether to leave white or black when the target pixel is a black pixel and the previous pixel to be superimposed is a white pixel. For example, when the target pixel is a thin black line “1” and the previous pixel to be superimposed is a non-fine line “0” of white pixels, the superimposition is performed with black priority. When the target pixel is a non-fine line “0” of a black pixel and the previous pixel to be superimposed is a non-fine line “0” of a white pixel, black is basically given priority. Make white pixels. Note 1 is that if the pixel is the third or fourth pixel in the main scanning direction in the reduction target group, it is set as a white pixel.

On the other hand, the sub-scanning direction reduction processing section 304 executes reduction processing in the sub-scanning direction by using the result of the thin line determination. FIG. 27 shows rules when the sub-scanning direction reduction processing unit 304 overlaps pixels in the sub-scanning direction. The sub-scanning direction reduction processing unit 304 executes a process of superimposing pixels in the sub-scanning direction according to the rule of FIG. Note that Note 1 in the figure means that if the pixel is the third or fourth pixel in the main scanning direction in the reduction target group, it is changed to a white pixel.
Indicates that the pixel is the last pixel in the sub-scanning direction in the group to be reduced, and that if a line before the output pixel is a black pixel, the pixel is set to a white pixel.

As described above, the thin line determination unit 302 performs the thin line determination of the target pixel, and uses the thin line determination result in the superimposition processing in the main scanning direction and the sub-scanning direction in the subsequent reduction processing. Since the superimposition is performed in the order of white thin line> white thin line candidate> black pixel> white pixel, it is possible to prevent interruption of the thin line due to simple thinning and black loss due to thinning with black pixel priority by OR thinning, thereby improving image quality. Can be achieved.

Although the reduction processing section 112 outputs a plurality of input pixels to the same address in accordance with the reduction ratio, the reduction processing in the sub-scanning direction is performed after the reduction processing in the main scanning direction. FIG. 28 shows a conceptual diagram in the case where 2 × 2 input pixels are output to the same address. Pixels A and B in the main scanning direction are superimposed on the first line in the above-mentioned order of priority, and a pixel M is output.
Are superimposed in the order of priority, and a pixel N is output. Then, the pixel M and the pixel N in the sub-scanning direction are superimposed in the above priority order, and the pixel P is finally output.

FIG. 29 is a conceptual diagram in the case of 1/4 magnification, and FIG. 30 is a flowchart for that. Reduction processing unit 1
In the case of １ ／, the main scanning direction reduction processing unit 303 reduces the Y0 line by superimposing in the order of X0, X1, X2, and X3, and writes the reduction result XY0 of the Y0 line into the memory 305.

Next, the Y1 line is defined as X0, X1, X2, X
The size is reduced by overlapping in the order of 3. And Y
Reduction result XY1 of one line and reduction result XY of Y0 line
The image is reduced by superimposing 0 on it, and the reduction result Y01 up to the Y1 line is written in the memory 305.

Next, the Y2 line is defined as X0, X1, X2, X
The size is reduced by overlapping in the order of 3. And Y
Reduction is performed by superimposing the reduction result XY2 of two lines and the reduction result Y01 up to the Y1 line, and writes the reduction result Y02 up to the Y2 line into the memory 305.

Further, the Y3 line is defined as X0, X1, X2,
The image is reduced by overlapping in the order of X3. And
Reduction is performed by superimposing the reduction result XY3 of the Y3 line and the reduction result Y02 of the Y2 line, and writing the reduction result Y03 of the Y3 line to the memory 305. This reduction result Y03 is the final output pixel.

As described above, after the processing in the main scanning direction of the pixel group to be reduced is completed, the reduction processing in the sub-scanning direction is performed. Therefore, it is sufficient to define two reduction processes in the main scanning direction and the sub-scanning direction, and there is an advantage that the circuit scale can be reduced. On the other hand, in the conventional method, three types of reduction processing, that is, reduction processing in the main scanning direction, the sub-scanning direction, and both the main and sub directions, are required, so that the circuit scale tends to be large.

Next, the image area separating circuit 102 will be described. Here, when performing the reduction process, a plurality of input pixels are output to the same address, and the image area separation result of each input pixel is not always the same. Simple thinning or OR
In the thinning-out, the image area separation data of the pixel finally effective is used as the image area separation result of the output pixel. However, since the conventional method is based on data that has been thinned out at random, halftone judgment results remain in images with many characters, and character judgment results do not appear in images with many halftones. Since it is left, there is a possibility that the determination result may not match the input image. In the present embodiment, the image area separation result of the output address at the time of reduction can be selected from outside so that a determination result suitable for the input image can be obtained.

FIG. 31 is a functional block diagram of the image area separating circuit 102. As shown in FIG.
For example, an image area separation unit 401 that determines whether a target pixel is a character or a halftone from input pixels of 8 × 8 pixels and outputs an image area separation result, and processes the image area separation result according to a mode parameter An output determination unit 402 that outputs the final image area separation result and a memory 403 that temporarily stores the output of the output determination unit 402 are provided.

The output judging section 402 can switch the processing according to the mode parameter selected and input by the user from the console. In the first mode, the image area separation unit 4
No. 01 outputs the image area separation result of the character irrespective of the image area separation result. In the second mode, when both the character and the halftone are included in the image area separation result output from the image area separation unit 401, the image area separation result of the character is output. In the third mode, when both the characters and the halftone are included in the image area separation result output from the image area separation unit 401, the image processing apparatus outputs the halftone image area separation result. In the fourth mode, a halftone image area separation result is output regardless of the image area separation result output from the image area separation unit 401. The fifth mode is
The reduction processing unit 112 performs reduction processing on the input image and outputs the image area separation result of the output pixels that have become valid. in this case,
The reduction processing unit 112 performs the reduction processing of the input image, and fetches the address of the output pixel that has become effective. The sixth mode is
The larger of the image area determination results of the input pixels is output.

As a result, the user can externally select the image area separation determination result of the output address at the time of reduction, so that a mode selection suitable for the input image can be made, and an image area determination result suitable for the input image is obtained. I can do it.

A specific example will be described with reference to FIGS. The input image shown in FIG.
FIG. 33 shows the result of reduction to 2, and FIG. 34 shows the result of OR thinning. FIG. 35 shows an example in which the determination result is output in the second mode with character priority. As shown in the figure, in the case of a character image, by performing the output determination of the image area separation result in the second mode, it is more likely that the character determination is performed as compared with the image area separation result of simple thinning or OR thinning. It can be seen that an image area separation result suitable for a character image can be output.

[0130]

As described above in detail, according to the present invention, there is provided an image scaling processing apparatus and an image scaling processing method capable of realizing a reduction in memory and an increase in processing speed when an input image is enlarged twice or more. Can be provided.

Further, according to the present invention, it is possible to provide an image scaling processing apparatus and an image scaling processing method capable of obtaining a smooth image with less unevenness when enlarging image data at an arbitrary magnification.

Further, according to the present invention, it is possible to provide an image scaling processing apparatus and an image scaling processing method capable of preventing image quality deterioration due to simple thinning or OR thinning when reducing image data at an arbitrary magnification.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image scaling processing apparatus according to an embodiment;

FIG. 2 is a functional block diagram of an enlargement processing unit in the image scaling processing apparatus according to the embodiment.

FIG. 3 is a diagram showing a pattern of a smoothing processing result;

FIG. 4 is a conceptual diagram of a four-fold enlargement in the main scanning direction in the embodiment.

FIG. 5 is a conceptual diagram of quadruple magnification in the sub-scanning direction in the embodiment.

FIG. 6 is a diagram showing a reference pattern used by a simple enlargement processing unit and a simple enlargement result in the embodiment.

7A is a diagram showing a pattern of an input pixel. FIG. 7B is a diagram showing an enlarged result of a conventional method. FIG. 7C is a diagram showing an enlarged result of the present method.

FIG. 8 is a conceptual diagram of the fraction processing at the time of enlargement in the embodiment.

FIG. 9 is a flowchart including a fraction process at the time of enlargement in the embodiment.

10A is a diagram showing a result of smoothing enlargement. FIG. 10B is a diagram showing a result of superimposing the enlarged result in the main scanning direction. FIG. 10C is a diagram showing a result of superimposing the enlarged result in the sub-scanning direction.

FIG. 11 is a diagram showing reference pixels in the fraction processing at the time of enlargement in the embodiment.

12A is a diagram showing another smoothing enlargement result. FIG. 12B is a diagram showing the superimposition result of the enlargement result in the main scanning direction. FIG. 12C is a diagram showing the superimposition result of the enlargement result in the sub-scanning direction.

FIG. 13 is a diagram showing reference pixels in the fraction processing at the time of enlargement in the embodiment.

FIG. 14 is a diagram showing some reference patterns, a smoothing result, and a conversion result in the fraction processing at the time of enlargement in the embodiment.

FIG. 15 is a diagram showing some other reference patterns, a smoothing result, and a conversion result in the fraction processing at the time of enlargement in the embodiment.

FIG. 16 shows a result of smoothing.

FIG. 17 is a diagram showing a peripheral pixel pattern referred to in fraction processing at the time of enlargement;

FIG. 18 is a diagram showing a smoothing result.

FIG. 19 is a diagram showing a peripheral pixel pattern referred to in fraction processing at the time of enlargement;

FIG. 20 is a diagram showing a smoothing result.

FIG. 21 is a diagram showing a peripheral pixel pattern referred to in the fraction processing at the time of enlargement;

FIG. 22 is a functional block diagram of a reduction processing unit in the image scaling processing apparatus according to the embodiment.

FIG. 23 is a diagram showing a reference pattern for determining a thin black line in the embodiment.

FIG. 24 is a diagram showing a reference pattern for determining a thin white line in the embodiment.

FIG. 25 is a diagram showing a reference pattern for determining a thin white line candidate in the embodiment.

FIG. 26 is a diagram illustrating rules when the main scanning direction reduction processing unit superimposes pixels in the main scanning direction.

FIG. 27 is a diagram showing rules when the sub-scanning direction reduction processing unit superimposes pixels in the sub-scanning direction.

FIG. 28 is a conceptual diagram showing the processing order of 2 × 2 pixel reduction processing in the above embodiment.

FIG. 29 is a conceptual diagram showing the processing order of the reduction processing of 4 × 4 pixels in the above embodiment.

FIG. 30 is a flowchart for a reduction process of 4 × 4 pixels.

FIG. 31 is a functional block diagram of an image area separation circuit in the image scaling processing apparatus of the embodiment.

FIG. 32 is a diagram showing an input image.

FIG. 33 is a diagram showing a result of reducing an input image to に よ っ て by simple thinning.

FIG. 34 is a diagram illustrating a result of OR thinning of an input image.

FIG. 35 is a diagram illustrating a result of determining an input image in a second mode with character priority.

[Explanation of symbols]

 Reference Signs List 101 Image memory 102 Image area separation circuit 103 Character scaling circuit 104 Projection processing circuit 105 Magnification counter operation circuit 106 Control circuit 107 Image signal synthesis circuit 108 Error diffusion processing circuit 109 Black and white compulsory circuit 201 Smoothing processing unit 202 Simple enlargement processing unit 203 Simple Enlargement processing units 204 to 206 Enlarged data creation unit 207 Output image data selection unit 301 Isolated point notch removal processing unit 302 Fine line determination unit 303 Main scanning direction reduction processing unit 304 Sub-scanning direction reduction processing unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshikazu Naito 2-3-8 Shimomeguro, Meguro-ku, Tokyo Matsushita Electric Transmission System Co., Ltd. F-term (reference) 5B057 BA23 CA02 CA06 CA07 CA12 CA16 CB02 CB06 CB07 CB12 CB16 CC02 CD05 CE02 CE05 CE13 CF03 CH11 CH18 DA08 DA17 DB02 DB05 DB08 DC16 DC36 5C072 AA03 BA03 BA09 BA15 UA20 5C076 AA02 AA21 AA22 AA27 AA32 BA05 BA08 BB03 BB07 BB13 BB15 BB44 CA10 CB01 5C077 LL05 PP07 LL05 LL06 PP55 PP65 PP68 PQ08 PQ17 PQ20 SS05

Claims (22)

[Claims] 1. An image scaling device in which a plurality of enlargement circuits are arranged in series such that an enlargement result of an enlargement circuit of a preceding stage is input to an enlargement circuit of a subsequent stage. Repeatedly input the number of times according to the magnification in the main scanning direction, take out the number of pixels corresponding to the enlargement ratio of the last enlargement circuit as enlarged pixels from the enlargement result output by the last enlargement circuit, and input the same pixel every time. An image magnification changing device for sequentially shifting the pixel take-out position in the main scanning direction. 2. An image scaling device in which a plurality of enlargement circuits are arranged in series such that an enlargement result of an enlargement circuit of a preceding stage is input to an enlargement circuit of a subsequent stage. Repeatedly input the number of times according to the magnification in the sub-scanning direction, take out the number of pixels corresponding to the enlargement ratio of the last enlargement circuit as enlarged pixels from the enlargement result output from the last enlargement circuit, and input the same pixel every time. An image magnification changing device for sequentially shifting the pixel take-out position in the sub-scanning direction. 3. A pixel pattern of M × M pixels corresponding to a reference pattern having a high degree of coincidence with an input image by comparing peripheral pixels of N × N pixels including a target pixel with a reference pattern of N × N pixels. As a result, the smoothing enlargement processing circuit and, if a plurality of pixels at the corner adjacent to the pixel of interest are the same data, replace the pixel corresponding to the corner with the same data as the plurality of pixels at the corner, A simple enlargement processing circuit that generates a pixel pattern of M × M pixels by performing the same replacement for the corner, and a simple enlargement processing circuit that generates the pixel pattern of M × M pixels by simply repeating the same data as the target pixel The smoothing enlargement processing circuit, the simple enlargement processing circuit and the simple enlargement processing circuit are configured to be switchable, so that the simple enlargement processing is performed as the magnification becomes larger. Image scaling apparatus characterized by a. 4. An image scaling device according to claim 3, wherein said smoothing enlargement processing circuit, simple enlargement processing circuit and simple enlargement processing circuit are used in combination in accordance with an enlargement ratio. 5. If three pixels at a corner adjacent to a pixel of interest have the same data and at least one pixel of a color different from the pixel of interest is included in a peripheral pixel near the corner, a pixel corresponding to the corner is provided. With the same data as the three pixels at the corner,
An image scaling device that generates a pixel pattern of M × M pixels by performing the same replacement for each corner around a target pixel. 6. When superimposing pixels in order to replace a block of N × N pixels obtained by enlarging a target pixel with N × 1 pixels or 1 × N pixels, reference is made to peripheral pixels of the target pixel. An image scaling device, wherein white pixels or black pixels are stored and superimposed so that a boundary line is smoothed. 7. An image processing circuit for removing at least one of an isolated point and a notch from an input image, and a reduction processing circuit for performing a reduction process on the input image from which the isolated point or the notch has been removed by the image processing circuit. Image magnification device equipped. 8. A thin line determining circuit for comparing peripheral pixels including a target pixel with a reference pattern to determine whether or not the target pixel is a thin line, and performing a reduction process of superimposing pixels in a main scanning direction or a sub-scanning direction. And a reduction processing circuit for determining a white pixel or a black pixel with reference to the thin line determination result of the thin line determination circuit. 9. The thin line determination circuit determines whether a target pixel is a black thin line, a white thin line,
9. The image scaling device according to claim 8, wherein it is determined whether the candidate is a white thin line candidate or another one. 10. A method of comparing a peripheral pixel including a target pixel with a reference pattern to determine whether or not the target pixel is a fine line, wherein a reference pattern for detecting a fine line based on the fine line width and continuity is used. And a thin line determination circuit. 11. A main scanning direction reduction processing circuit for reducing a pixel group to be reduced by superimposing pixels in the main scanning direction, a reduction result of a current line output from the main scanning direction reduction processing circuit, and a previous line. And a sub-scanning direction reduction processing circuit that superimposes the reduction results in the sub-scanning direction up to the above. 12. An image scaling device for switching between character image processing and halftone image processing using an image area separation result, wherein the function of determining the image area separation result of an output pixel is as follows: (1) All the image area separation results of output pixels are converted to characters. (2) If at least one pixel is included in the pixel group to be reduced, the image area separation result is output. The image area separation result of the pixel is defined. (3) If at least one pixel is included in the pixel group to be reduced, the image area separation result of the output pixel is set to halftone. (4) All image area separation results of output pixels are converted to halftones. (5) Image area separation results of pixels that become effective as a result of reduction processing are used as image pixel separation results of output pixels. The largest number of images in the image area separation results for each pixel An image scaling device wherein any of the above (1) to (6) can be selected, wherein the area separation result is set as the image area separation result of the output pixel. 13. The same pixel is repeatedly input to the head enlargement circuit arranged in series in accordance with the magnification in the main scanning direction or the sub-scanning direction, and the output of the former enlargement circuit is inputted to the latter enlargement circuit. Then, from the enlargement result output by the last enlargement circuit, the number of pixels corresponding to the enlargement ratio of the last enlargement circuit is extracted as an enlargement pixel, and each time the same pixel is input, the extraction position of the pixel is set in the main scanning direction or the sub-scanning direction. An image scaling method characterized by sequentially shifting in the direction. 14. A smoothing enlargement processing circuit for enlarging a pixel of interest by smoothing processing, a simple enlargement processing circuit for enlarging a pixel of interest by simple enlargement processing, and a simple enlargement processing circuit for enlarging the pixel of interest by simple enlargement processing,
An image scaling method characterized by switching so as to perform a simple enlargement process as the magnification increases. 15. A smoothing enlargement processing circuit for enlarging a target pixel by smoothing processing, a simple enlargement processing circuit for enlarging a target pixel by simple enlargement processing, and a simple enlargement processing circuit for enlarging a target pixel by simple enlargement processing.
An image scaling method characterized in that the combination is changed in accordance with an enlargement ratio and enlargement processing is performed. 16. If three pixels at a corner adjacent to a pixel of interest have the same data and at least one pixel of a color different from the pixel of interest is included in a peripheral pixel near the corner, a pixel corresponding to the corner is provided. Is replaced with the same data as the three pixels at the corner, and the same replacement is performed for each corner around the pixel of interest, thereby generating a pixel pattern of M × M pixels. 17. When superimposing pixels in order to replace a block of N × N pixels obtained by enlarging a target pixel with N × 1 pixels or 1 × N pixels, reference is made to peripheral pixels of the target pixel. An image scaling method, wherein white pixels or black pixels are stored and superimposed so that a boundary line is smoothed. 18. An image scaling method comprising: removing at least one of an isolated point and a notch from an input image; and thereafter performing a reduction process on the input image. 19. A method for comparing a peripheral pixel including a pixel of interest with a reference pattern to determine whether the pixel of interest is a fine line, and performing the thin line determination when performing a reduction process of superimposing pixels in the main scanning direction or the sub-scanning direction. An image scaling method, wherein a white pixel or a black pixel is determined with reference to a result. 20. When comparing a peripheral pixel including a target pixel with a reference pattern to determine whether or not the target pixel is a fine line, a reference pattern for detecting a fine line based on the fine line width and continuity is used. Thin line determination method. 21. A reduction process in a main scanning direction is performed on a group of pixels to be reduced by superimposing pixels in the main scanning direction, and a reduction result of a current line and a reduction result in a sub scanning direction up to a previous line are overlapped. An image scaling method, further comprising performing a reduction process in the sub-scanning direction. 22. An image scaling method for switching between processing of a character image and processing of a halftone image using an image area separation result, wherein a method of determining the image area separation result of an output pixel is as follows: (1) All the image area separation results of output pixels are converted to characters. (2) If at least one pixel is included in the pixel group to be reduced, the image area separation result is output. The image area separation result of the pixel is defined. (3) If at least one pixel is included in the pixel group to be reduced, the image area separation result of the output pixel is set to halftone. (4) All image area separation results of output pixels are converted to halftones. (5) Image area separation results of pixels that become effective as a result of reduction processing are used as image pixel separation results of output pixels. The largest number of images in the image area separation results for each pixel An image scaling method for selecting any one of the above (1) to (6), using the area separation result as an image area separation result of output pixels.