JPH05219359A - Picture processor - Google Patents

Abstract

PURPOSE:To enable the transfer without deleting a thin line at picture reduction by expanding the width of a thin line included in a read picture and applying magnification processing and then applying reduction processing to the picture. CONSTITUTION:A picture data input section 70 applies multi-value processing conversion to picture data of an original and applies 4-value processing to the data while taking a histogram and stores the result once to a memory 73. Then the inputted know data are subject to interpolation processing in response to a magnification commanded by a conversion processing section 71e of the input section 70 and picture element data after the magnification data are obtained and the width of a thin line is expanded. Then 4-value data are compressed by a compression processing section 71h by using run length coding. Then a picture data output section 72 decodes picture data stored in the memory 73 while being compressed and implements error spread of the 4-value data offering smooth expression of intermediate tone more than the binary data and the result is transferred to a laser output section 72d. Then a blur of an original at reduction/magnification processing is eliminated and the data are transferred without deleting the thin line.

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 such as a digital copying machine.

[0002]

2. Description of the Related Art Conventional digital copying machines and analog copying machines have a function of transferring a read image at the same size and enlarging or reducing it to transfer it onto a transfer sheet.

In a digital copying machine, a document is reduced by using a simple sampling method or the like for image data forming an image.

[0004]

However, in the case of reduction processing, in an analog copying machine, thin and thin characters have disappeared without being transferred because of the limit of resolution of an optical system.

On the other hand, in the conventional digital copying machine, the image data is reduced by thinning out the image data by using the simple sampling method or the like as described above. Therefore, the width of one pixel, that is, the width of one dot is obtained. If there is only a thin line, if the reduction ratio becomes large, it will be erased without being transferred.

Therefore, the present invention provides an image processing apparatus capable of transferring a thin line without erasing it when the image is reduced.

[0007]

According to the present invention, there is provided an image processing apparatus having a function of optically reading an original image, and a means for widening a thin line included in the read image,
An apparatus is provided which comprises means for reducing an image in which thin lines are widened by the means.

Further, the means for widening the thin line performs a thinning process on the background other than the characters, figures and symbols of the binarized image and the means for binarizing the image data of the read image. Means, means for inverting the binary value of the image data for the thinned image, means for expanding the image data area representing any of the characters, figures and symbols of the read image, and the means for inverting It may include means for obtaining a logical product of the image data formed by the means and the image data formed by the expansion processing means.

[0009]

The thin line included in the read image is widened before the reduced size of the read image.

Further, in the process of widening the thin line, the image data of each pixel of the read image is first binarized and
Thinning processing is performed on pixels corresponding to the background other than the characters, figures, and symbols in the binarized image. Further, the binary value of each pixel is inverted with respect to the thinned image.
On the other hand, the image data area representing any of the characters, figures and symbols of the read image is expanded. Then, the logical product of the image data formed by the inversion means and the image data formed by the expansion processing means is calculated, and the image in which the thin line is held is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital copying machine according to the present invention will be described in detail below with reference to the drawings.

FIG. 7 is a block diagram schematically showing the configuration of an embodiment of the present invention.

As shown in FIG. 7, the digital copying machine 30 of this embodiment includes a scanner section 31 and a laser printer section 3.
2. A multi-stage paper feeding unit 33 and a sorter 34 are provided. The scanner unit 31 is composed of a document placing table 35 made of transparent glass, an automatic document feeder (ADF) 36 compatible with both sides, and a scanner unit 40.

The multi-stage sheet feeding unit 33 includes the first cassette 5
It has the 1st, 2nd cassette 52, the 3rd cassette 53, and the 5th cassette 55 which can be added by selection. In the multi-stage sheet feeding unit 33, the sheets are sent out one by one from the sheets stored in the cassettes of the respective stages and are conveyed toward the laser printer unit 32. The ADF 36 sets a plurality of originals at one time, automatically feeds the originals one by one to the scanner unit 40, and causes the scanner unit 40 to read one side or both sides of the original according to the operator's selection. Is configured.

The scanner unit 40 forms a lamp reflector assembly 41 for exposing a document, a plurality of reflecting mirrors 43 for guiding a reflected light image from the document to a charge coupled device (CCD) 42, and a reflected light image from the document on the CCD 42. It includes a lens 44 for imaging. Scanner unit 31
When scanning a document placed on the document table 35, the scanner unit 4 is arranged along the lower surface of the document table 35.
0 is configured to read an original image while moving, and when the ADF 36 is used, the original image is read while the original is conveyed while the scanner unit 40 is stopped at a predetermined position below the ADF 36. Is configured.

The image data obtained by reading the original image with the scanner unit 40 is sent to an image processing unit (not shown), which will be described later, and subjected to various processing, and then temporarily stored in the memory of the image processing unit. In response to the output instruction, the image data in the memory is given to the laser printer unit 32 to form an image on a sheet.

The laser printer unit 32 includes a manual document tray 45, a laser writing unit 46, and an electrophotographic process unit 47 for forming an image. The laser writing unit 46 is a semiconductor laser that emits a laser beam according to the image data from the above-mentioned memory, a polygon mirror that deflects the laser beam at a constant angular velocity, and a laser beam that is deflected at a constant angular velocity is exposed to the electrophotographic process section 47. Body drum 48
It has an f-θ lens and the like for performing correction so that the angular velocity is deflected.

The electrophotographic process section 47 comprises a charging device, a developing device, a transfer device, a peeling device, a cleaning device, a static eliminator and a fixing device 49 around the photosensitive drum 48 in a known manner. A transport path 50 is provided on the downstream side of the fixing device 49 in the transport direction of the sheet on which the image is to be formed, and the transport path 50 communicates with the sorter 34.
And a conveyance path 58 leading to the multi-stage sheet feeding unit 33. The transport path 58 is branched in the multi-stage sheet feeding unit 33, and the reverse transport path 50 is used as a transport path after the branch.
a and a double-sided / composite transport path 50b are provided. The reverse conveyance path 50a is a conveyance path for reversing the front and back sides of a sheet in the double-sided copy mode for copying both sides of a document. The double-sided / composite conveyance path 50b conveys a sheet from the reverse conveyance path 50a to the image forming position of the photosensitive drum 48 in the double-sided copy mode, or forms an image of different originals or toners of different colors on one side of the sheet. This is a transport path for transporting the paper to the image forming position of the photosensitive drum 48 without inverting the paper in the single-sided synthetic copy mode for performing the synthetic copy.

The multi-stage paper feeding unit 33 includes a common transport path 56, which is the first cassette 51 and the second cassette 51.
The sheets from the cassette 52 and the third cassette 53 are carried out toward the electrophotographic process section 47. The common transport path 56 joins the transport path 59 from the fourth cassette 55 on the way to the electrophotographic process section 47 and communicates with the transport path 60. The conveyance path 60 merges with the conveyance path 61 from the double-sided / composite conveyance path 50b and the manual feed tray 45 at a confluence point 62 to reach an image forming position between the photosensitive drum 48 of the electrostatic photography process section 47 and the transfer device. The confluence point 62 of these three transport paths is provided at a position close to the image forming position. Therefore, the laser writing unit 46 and the electrophotographic process unit 47 are
In the above, the image data read from the above-mentioned memory is formed as an electrostatic latent image on the surface of the photosensitive drum 48 by scanning the laser beam by the laser writing unit 46, and visualized by the toner. The toner image is electrostatically transferred and fixed on the surface of the sheet conveyed from the multi-stage sheet feeding unit 33. The sheet on which the image is formed in this manner is sent from the fixing device 49 to the sorter 34 via the transport paths 50 and 57, or is transported to the reverse transport path 50a via the transport paths 50 and 58.

Next, the structure and function of the image processing unit included in the digital copying machine 30 of this embodiment will be described.

FIG. 8 is a block diagram schematically showing the structure of the image processing section.

The image processing unit included in the digital copying machine 30 includes an image data input unit 70, an image processing unit 71, an image data output unit 72, a memory 73 including a RAM (random access memory) and a CPU (central processing unit). Arithmetic unit) 74. The image data input unit 70 is a CCD
The unit 70a, the histogram processing unit 70b, and the error diffusion processing unit 70c are included.

The image data input section 70 has the CC shown in FIG.
The image data of the original read from D42 is converted to multi-valued (8
Bit) conversion and taking a histogram as a multivalued digital amount, the image data is converted into 4 by the error diffusion method.
The memory 73 is configured to be digitized and temporarily stored in the memory 73. That is, in the CCD unit 70a, after the analog electric signal corresponding to each pixel density of the image data is A / D converted, MTF correction, black-and-white correction or gamma correction is performed.
The digital signal of 56 gradations (8 bits) is output to the histogram processing unit 70b.

In the histogram processing section 70b, the digital signal output from the CCD section 70a is added for each pixel density of 256 gradations to obtain density information (histogram data), and if necessary, the obtained histogram data is It is sent to the CPU 74 or as pixel data to the error diffusion processing unit 70c. Error diffusion processing unit 70c
Then, the error diffusion method which is a kind of pseudo halftone processing, that is, 4
A digital signal of 8 bits / pixel output from the CCD unit 70a is converted into 2 bits (4 values) by a method of reflecting a quantization error in the quaternization judgment of an adjacent pixel to faithfully reproduce the local area density in the original. A redistribution operation is performed to reproduce the above.

The image processing unit 71 includes multi-valued processing units 71a and 71b, a synthesis processing unit 71c, a density conversion processing unit 71d, a scaling processing unit 71e, an image processing unit 71f, an error diffusion processing unit 71g and a compression processing unit 71h. Contains. The image processing section 71 is a processing section for finally converting the input image data into image data desired by the operator, and this processing is carried out until it is stored in the memory 73 as finally converted output image data. It is configured to be processed by the department. However, each of the above-described processing units included in the image processing unit 71 functions as necessary and may not function.

That is, in the multilevel halftoning processing units 71a and 71b, the four-valued data in the error diffusion processing unit 70c is converted again into 256 gradations.

In the synthesizing section 71c, a logical operation for each pixel, that is, a logical sum, a logical product or an exclusive logical sum is selectively performed. The data to be calculated are pixel data stored in the memory 73 and bit data from the pattern generator (PG).

In the density conversion processing unit 71d, the relationship between the input density and the output density is arbitrarily set for the 256 gradation digital signal based on a predetermined gradation conversion table.

In the conversion processing unit 71e, pixel data (density value) for the target pixel after scaling is obtained by performing interpolation processing with the known data that is input according to the designated scaling ratio, and the sub-scanning is performed. Is scaled, the main scanning is scaled.

In the image processing section 71f, various image processings can be performed on the input pixel data, and information collection such as feature extraction can be performed on the data string.

The error diffusion processing section 71g performs the same processing as the error diffusion processing section 70c of the image data input section 70.

In the compression processing section 71h, 4-valued data is compressed by the coding called runless method. Regarding the compression of the image data, the compression functions in the final processing loop when the final output data is completed.

The image data output unit 72 includes a restoration unit 72a, a multi-value processing unit 72b, an error diffusion processing unit 72c, and a laser output unit 72d.

The image data output unit 72 restores the image data stored in the memory 73 in a compressed state to the original 25
The laser output unit 7 converts the gradation into 6 gradations again and performs error diffusion of the 4-valued data, which is a smoother halftone expression than the binary data.
It is configured to transfer data to 2d. That is,
The decompression unit 72a decompresses the image data compressed by the compression processing unit 71h.

In the multi-value processing section 72b, the image processing section 71
Processing similar to that of the multi-value quantization processing units 71a and 71b is performed. In the error diffusion processing unit 72c, the image data input unit 70
Processing similar to that of the error diffusion processing unit 70c is performed.

In the laser output section 72d, the digital pixel data is converted into a laser on / off signal based on a control signal from a sequence controller (not shown), and the laser is turned on / off.

The data handled by the image data input section 70 and the image data output section 72 is basically in the form of four-valued data in order to reduce the capacity of the memory 73.
Although stored in 3, it is also possible to process in the form of binary data.

Next, one embodiment of the means for widening the fine lines included in the image, which is the main part of the present invention, will be described.

The means for widening the thin line included in the image according to the present invention performs a process for thickening the thin line portion of the image data before the scaling process. Further, since this is a program that is basically processed by the CPU, FIG.
It is not necessary to change the circuit of the image processing unit shown in FIG.

FIG. 1 is a flow chart showing a processing procedure of an embodiment of a means for widening a thin line included in an image.

First, the four-valued image data stored in the memory 73 shown in FIG. 8 is again multivalued into 256-gradation image data, and then, for example, black is set to 0 by the binarizing means.
It is binarized into binary data in which white is 255 (step S1). Black generally represents a character, a figure, a symbol, or the like, and white represents a background. Next, thinning processing is performed on the white data based on a thinning algorithm that is a means for performing thinning processing (step S2). That is, this causes the thin line portion to widen. Then, the binary image data obtained by subjecting the background to the thinning processing is black-white inverted by the means for inverting the binary of the image data (step S3). That is, 0 is set to 255 and 25
Set 5 to 0. As a result, the thick thin line portion has the data represented by the binary number 11111111.

On the other hand, expansion processing is performed on the image data of 256 gradations based on an expansion algorithm which is a means for performing expansion processing (step S4). That is, the thin line portion is widened with 256 gradation data. Next, the value 2 inverted in step S3
Using the value inversion data and the 256-gradation expansion data obtained in step S4, the logical product of each pixel is calculated based on the means for calculating the logical product, and A
ND synthesis processing is performed (step S5). Then, finally, interpolation scaling processing is performed on the image data obtained by the AND synthesis processing (step S6), the image of the processing result is held in the memory, and then transferred using the image output unit.

Therefore, since the digital copying machine according to the present embodiment is provided with the above-mentioned means, the circuit for image processing is changed such as the disappearance of one dot line at the time of reduction / magnification processing and the blurring of the pencil-written original. Can be prevented without

FIG. 2 shows an example of an image in the course of a series of processing in the above flow chart.
As shown in the figure, the character A is widened as data of 256 gradations.

Next, an example of a simple sampling method of the above-described thinning algorithm, expansion algorithm, AND combination processing, and scaling processing will be described with reference to the drawings.

FIG. 3 is a processing example according to an example of a thin line algorithm, FIG. 4 is a processing example according to an example of an expansion algorithm,
FIG. 5 shows an example of the AND combination process, and FIG.
An example of the simple sampling method will be shown.

The thinning is generally an operation of thinning the line width from a given character, figure, or symbol to extract the center line of width 1. In this embodiment, thinning is performed on the background data as described above. The thinning algorithm follows the rules shown below.

(A) The data of the pixel to be processed is white (10
255) in radix, that is, the background. (B) 4-If there is at least one black (decimal 0) pixel in the vicinity and 8-there are two or more white pixels,
The data of the pixel to be processed is changed from white to black.

Four examples processed according to this rule are shown in FIGS. 3A to 3D. However, 4-neighborhood is 3 × 3 pixels on the left side of FIG. 3A, and is four black pixels with respect to the central pixel of the processing target, and 8-neighborhood is all eight surrounding pixels. It is a pixel.

For example, in FIG. 3B, since the central pixel to be processed is white, the left 4-neighboring pixels are black, and there are 6 white pixels in 8-neighborhood, the above-mentioned rule is satisfied and the center is satisfied. The pixel data is converted to black.

The thinning algorithm is not limited to the above-described embodiment, and may be one that follows other rules as long as the same effect can be obtained.

The dilation algorithm of this embodiment complies with the following rules.

(A) The data of the pixel to be processed is white (10
255) in radix, that is, the background. (B) In the 8-neighboring pixels, the largest value of the data other than white is set as the processing pixel data.

For example, in FIG. 4, the central pixel to be processed is white (255 in decimal), and 25 in 8-neighborhood.
The data 220 shown in FIG. 4B is obtained by using 220, which is the largest value other than 5, as the data of the pixel to be processed.

The expansion algorithm is not limited to the embodiment described above, and may follow other rules as long as the same effect can be obtained.

The AND synthesizing process is to obtain the logical product of the inversion data of the thin line widened by the thinning algorithm and the data of 256 gradations obtained by the expansion algorithm in each pixel.

As shown in FIG. 5, A of image A and image B
The ND compositing process is accomplished by performing a logical AND on each bit of binary data at each pixel. Therefore, the decimal number in the image A is 255, that is, the binary number is 1.
The data of the image B corresponding to the pixel of 11111111 is maintained as it is after the processing, and is 0 in decimal number in the image A,
That is, the image B corresponding to the binary number 00000000 pixels
Data becomes 0 in decimal after processing.

The simple sampling method of this embodiment is executed by the following procedure. As shown in FIG. 6, for example, 4 × 4
If the pixel matrix of is reduced to 1/2, first,
Pixels in the fourth and fourth columns are thinned out to obtain a pixel matrix of (B), then the second and fourth rows are thinned out to obtain a pixel matrix of (C) and reduced to 1/2. As described above, the method of thinning out pixels to reduce the size is collectively referred to as a simple sampling method. The reduction of an arbitrary scale is executed by using this simple sampling method and interpolation processing.

Therefore, by using these algorithms described above, it is possible to prevent the disappearance of one dot line during image reduction / magnification processing, fading of the pencil-written original, and the like, and to save the thin line.

[0060]

As described above in detail, according to the present invention, a means for widening a fine line included in a read image,
Since a means for reducing the image processed by the means for enlarging the width is provided, a circuit for image processing such as disappearance of one dot line at the time of reduction / magnification processing, blurring of a pencil-written original, etc. is provided. It can be prevented without changing.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a processing procedure of an embodiment of a means for widening a thin line according to the present invention.

FIG. 2 is an explanatory diagram showing a processing example according to an embodiment of means for widening a thin line according to the present invention.

FIG. 3 is an explanatory diagram illustrating a processing example according to an example of a thinning algorithm.

FIG. 4 is an explanatory diagram showing a processing example according to an example of an expansion algorithm.

FIG. 5 is an explanatory diagram showing a processing example according to an example of an AND combination processing.

FIG. 6 is an explanatory diagram showing an example of a simple sampling method.

FIG. 7 is a sectional view schematically showing the configuration of an example of a digital copying machine according to the present invention.

FIG. 8 is a block diagram schematically showing a configuration of an image processing unit included in the digital copying machine according to the present invention.

[Explanation of symbols]

 70 image data input unit 71 image processing unit 72 image data output unit 73 memory 74 CPU

Claims (2)

[Claims] 1. An image processing apparatus having a function of optically reading a document image, comprising means for widening a thin line included in a read image, and reduction processing for an image having the thin line widened by the means. An image processing apparatus comprising: 2. A means for widening the thin line, a means for binarizing image data of a read image, and a thinning process for a background other than characters, figures and symbols of the binarized image. A means for performing, a means for inverting the binary value of the image data for the thinned image, and a means for expanding the image data area representing any of the characters, figures and symbols of the read image. An image processing apparatus comprising: a means for obtaining a logical product of the image data formed by the inverting means and the image data formed by the expansion processing means.