JP2002152511A - Image processor, image processing method and computer readable medium recording program for executing that method in computer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the operation such that an edge having a level difference is made smoother and longitudinal, lateral or oblique line has a uniform line width when a document is read out with a scanner, a digital image signal thus obtained is subjected to image processing and an image is reproduced on a transfer sheet by means of a printer. SOLUTION: A decision is made whether an interested pixel is included in a halftone part or not, and if it is not included, a decision is made whether a pattern of 3×3 matrix of 9 pixels including the interested pixel matches a level difference pattern, an oblique line pattern, a longitudinal line pattern or a lateral line pattern, previous prepared as a sample, or not. If it matches any one sample pattern, Ndpi one pixel 1 bit binary gray scale of the interested pixel is converted into gray scale of Ndpi one pixel M gray scale corresponding to the matched sample pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and an image processing method, and more particularly to an Ndpi pixel 1 bit 2 bits.
Value image data is Ndpi one pixel M (where M> 2)
The present invention relates to a technique for reproducing high-quality images by converting the image data into value image data and performing correction processing on steps or diagonal lines of the images. Here, the value of N is not particularly limited, but is, for example, 400, 600, or 1200.

[0002]

2. Description of the Related Art In general, as a device for reading an original with a scanner or the like, performing image processing on the obtained digital image signal, and reproducing an image on transfer paper in a printer or the like, for example, a digital copying machine, a digital multifunction machine, etc. There is. A digital multifunction peripheral is a device having a scanner function, a printer function, a facsimile function, and the like in addition to a copying function. In recent years, plotters such as digital copiers and digital multifunction peripherals have come to handle data of the same resolution in both copying and printer operations.

[0003] For example, Japanese Patent Laid-Open Publication No. Hei 10-10809 discloses an image processing method for binarizing or multi-leveling input image data. This method improves the reproducibility of an edge portion included in an image by determining a dot arrangement with reference to adjacent pixels located on the left and right of a target pixel.

[0004]

Generally, in order to reproduce a high-quality image from image data of a document read by a scanner or the like, an edge portion having a step is made smoother, or a vertical line, a horizontal line, or an oblique line is formed. Is desired to have a uniform line width. However, the image processing method disclosed in the above publication, for example, smoothing of the step portion,
It does not control the line width.

[0005] The present invention has been made in view of the above circumstances, and has been achieved by smoothing an edge portion having a step or by controlling a vertical line, a horizontal line, and an oblique line to have a uniform line width. It is an object of the present invention to provide an image processing device capable of reproducing a high-quality image.

Another object of the present invention is to provide an image processing method for smoothing an edge portion having a step and controlling a vertical line, a horizontal line, and an oblique line to have a uniform line width.

[0007]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, an image processing apparatus according to claim 1 is a device for converting input image data of one bit, one bit and two pixels into image data of one pixel, M value, wherein a target pixel and the target pixel are provided. Acquisition means for acquiring a pattern of a 3 × 3 matrix-like pixel group composed of eight pixels surrounding, and one or more sample patterns prepared in advance for the 3 × 3 matrix-like pixel group are stored. Storage means, determining means for determining whether the pattern of the 3 × 3 matrix pixel group matches the sample pattern, and determining whether the pattern of the 3 × 3 matrix pixel group is a specific sample pattern of the sample patterns. And converting means for converting the gradation of the target pixel into a value corresponding to the specific sample pattern when they match.

According to the first aspect of the present invention, the 3 × 3 matrix pattern of the target pixel and the eight pixels surrounding the target pixel matches the gradation of the target pixel of one bit per pixel. According to the sample pattern to be converted, the gradation is converted into the gradation of one pixel M value.

According to a second aspect of the present invention, there is provided an image processing apparatus for converting input image data of one bit and one binary value into image data of one pixel M value in a halftone portion. A halftone determining means for determining whether or not the pixel of interest is included, and a 3 × 3 matrix-like pixel including the pixel of interest and eight pixels surrounding the pixel of interest when the pixel of interest is not included in the halftone portion Acquisition means for acquiring a group pattern; storage means for storing one or more sample patterns prepared in advance for a 3 × 3 matrix pixel group; and a pattern of the 3 × 3 matrix pixel group being a sample pattern. Pattern determining means for determining whether or not the pattern matches the pattern of the 3 × 3 matrix pixel group. If it matches the over emissions, characterized by comprising a conversion means for converting the gray level of the pixel of interest to a value corresponding to the specific sample pattern.

According to the second aspect of the present invention, when the target pixel is not included in the halftone portion, that is, when the target pixel is a background portion or a character portion, the 1-bit 1-bit binary pixel of the target pixel is used. The gradation is converted into a gradation of one pixel M value according to a sample pattern in which the pattern of the 3 × 3 matrix composed of the pixel of interest and eight pixels surrounding the pixel of interest matches.

According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect,
When the specific sample pattern is a pattern corresponding to a step portion of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and the maximum.

According to the third aspect of the present invention, when the pattern of the 3 × 3 matrix including the target pixel matches the sample pattern of the stepped portion, the gradation of the target pixel of one bit per bit of one pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

According to a fourth aspect of the present invention, in the image processing apparatus according to the first or second aspect,
When the specific sample pattern is a pattern corresponding to an oblique line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum.

According to the fourth aspect of the invention, when the pattern of the 3 × 3 matrix including the target pixel coincides with the sample pattern of the oblique line, the gradation of the target pixel of one bit per pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

According to a fifth aspect of the present invention, in the image processing apparatus according to the first or second aspect,
When the specific sample pattern is a pattern corresponding to a vertical line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum.

According to the fifth aspect of the present invention, when the 3 × 3 matrix pattern including the target pixel matches the vertical line sample pattern, the gradation of the target pixel of one bit per pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

According to a sixth aspect of the present invention, in the image processing apparatus according to the first or second aspect,
When the specific sample pattern is a pattern corresponding to a horizontal line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum.

According to the sixth aspect of the invention, when the pattern of the 3 × 3 matrix including the target pixel matches the horizontal line sample pattern, the gradation of the target pixel of one bit per pixel is one pixel. The conversion is performed so that the gradation of the M value becomes a gradation between white and black.

An image processing apparatus according to a seventh aspect of the present invention is the image processing apparatus according to the first or second aspect,
When the pattern of the 3 × 3 matrix pixel group does not match the sample pattern, the conversion unit corresponds to the gray level corresponding to one pixel M value of the target pixel to the gray level of the original one pixel binary value. It is characterized by a value.

According to the seventh aspect of the present invention, if the pattern of the 3 × 3 matrix including the target pixel does not match the sample pattern, the gradation of the target pixel of one bit per pixel is one pixel M The value gradation is also converted to the same white or black as the original.

In the image processing apparatus according to the present invention, when the pixel of interest is included in a halftone portion, the conversion means may include a conversion unit for the pixel of interest. The gradation corresponding to the pixel M value is set to a value corresponding to the gradation in the original binary value of one pixel.

According to the eighth aspect of the invention, when the target pixel is included in the halftone portion, the gradation of the target pixel of one bit and one binary value is the same as that of the M value of one pixel. Converted to the same white or black.

According to a ninth aspect of the present invention, in the image processing apparatus according to the second aspect, the halftone determining means determines that the number of white pixels continuously input as the pixel of interest is: When the number of pixels existing between the black portions of the dither is less than or equal to, or when the number of black pixels continuously input as the pixel of interest is less than the number of pixels constituting the black portion of the dither, The pixel group is determined to be included in the halftone portion.

According to the ninth aspect of the present invention, based on the number of continuously inputted white pixels or the number of continuously inputted black pixels, the target pixel is a white portion of dither or a dithered portion. It is determined whether or not it is included in the black portion of.

According to a tenth aspect of the present invention, in the image processing apparatus according to the first aspect, the acquisition unit, the determination unit, and the conversion unit are SIMD.
(Single instruction multi
and a ple data stream type processor.

According to the tenth aspect of the present invention, the gradation conversion processing from one bit, one bit binary to one pixel M value is performed by:
It is performed with middleware consisting of a SIMD type processor with high performance.

In the image processing apparatus according to the present invention, the halftone determining means, the obtaining means, the pattern determining means, and the converting means may be of an SIMD type. It is characterized by being constituted by a processor.

According to the eleventh aspect of the present invention, the gradation conversion processing from one-bit one-bit binary to one-pixel M-value is performed by:
It is performed with middleware consisting of a SIMD type processor with high performance.

According to another aspect of the present invention, there is provided an image processing method comprising:
In converting the bit binary input image data into one pixel M-value image data, the pattern of a pixel of interest and a 3 × 3 matrix pixel group composed of eight pixels surrounding the pixel of interest is 3 × 3 Determining whether the matrix pixel group matches one or more sample patterns prepared in advance; and determining whether the pattern of the 3 × 3 matrix pixel group is a specific sample pattern of the sample patterns. And converting the tone of the pixel of interest to a value corresponding to the specific sample pattern.

According to the twelfth aspect of the present invention, the 3 × 3 matrix pattern of the target pixel and the eight pixels surrounding the target pixel matches the gradation of the target pixel of one bit per pixel. According to the sample pattern to be converted, the gradation is converted into the gradation of one pixel M value.

In the image processing method according to the thirteenth aspect, when the input image data of one bit and one binary value is converted into the image data of one pixel M value, the target pixel is included in the halftone portion. Determining whether or not
When the target pixel is not included in the halftone portion, the pattern of the 3 × 3 matrix pixel group including the target pixel and eight pixels surrounding the target pixel is 3 ×
1 prepared in advance for a 3 matrix pixel group
Or a step of determining whether or not the pixel pattern matches two or more sample patterns; and, when the pattern of the 3 × 3 matrix pixel group matches a specific sample pattern among the sample patterns, Converting to a value corresponding to the specific sample pattern.

According to the thirteenth aspect of the present invention, when the target pixel is not included in the halftone portion, that is, when the target pixel is a background portion or a character portion, the 1-bit 1-bit binary target pixel is not included. The gradation is converted into a gradation of one pixel M value according to a sample pattern in which the pattern of the 3 × 3 matrix composed of the pixel of interest and eight pixels surrounding the pixel of interest matches.

According to a fourteenth aspect of the present invention, in the image processing method according to the twelfth or thirteenth aspect, when the specific sample pattern is a pattern corresponding to a step of an image, Is converted into a value between zero and the maximum.

According to the fourteenth aspect of the present invention, when the 3 × 3 matrix pattern including the target pixel matches the sample pattern of the stepped portion, the gradation of the target pixel of one bit per pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

According to a fifteenth aspect of the present invention, in the image processing method according to the twelfth or thirteenth aspect, when the specific sample pattern is a pattern corresponding to an oblique line of an image, Is converted into a value between zero and the maximum.

According to the fifteenth aspect, when the 3 × 3 matrix pattern including the target pixel matches the sample pattern of the oblique line, the gradation of the target pixel of one bit per pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

In the image processing method according to the present invention, when the specific sample pattern is a pattern corresponding to a vertical line of an image, the target pixel Is converted into a value between zero and the maximum.

According to the sixteenth aspect of the present invention, when the pattern of the 3 × 3 matrix including the target pixel matches the vertical line sample pattern, the gradation of the target pixel of one bit per pixel is one. The conversion is performed so that the gray level of the pixel M value becomes a gray level between white and black.

According to a seventeenth aspect of the present invention, in the image processing method according to the twelfth or thirteenth aspect, when the specific sample pattern is a pattern corresponding to a horizontal line of an image, It is characterized in that the gradation is converted into a value between zero and the maximum.

According to the seventeenth aspect, when the 3 × 3 matrix pattern including the target pixel matches the horizontal line sample pattern, the gradation of the target pixel of one bit per pixel is one pixel. The conversion is performed so that the gradation of the M value becomes a gradation between white and black.

Further, in the image processing method according to the present invention, when the pattern of the 3 × 3 matrix pixel group does not match the sample pattern in the invention of the twelfth or thirteenth aspect, The method further includes a step of setting a gradation corresponding to one pixel M value of the target pixel to a value corresponding to the gradation in the original one pixel binary value.

According to the eighteenth aspect of the present invention, if the pattern of the 3 × 3 matrix including the target pixel does not match the sample pattern, the gradation of the target pixel of one bit per pixel is one pixel M The value gradation is also converted to the same white or black as the original.

According to a nineteenth aspect of the present invention, in the image processing method according to the thirteenth aspect, when the target pixel is included in a halftone portion, the target pixel corresponds to one pixel M value of the target pixel. The method further includes a step of setting the gradation to be set to a value corresponding to the gradation in the original binary value of one pixel.

According to the nineteenth aspect of the present invention, when the target pixel is included in the halftone portion, the gradation of the target pixel having one bit and two bits per pixel is the same as that of the M value of one pixel. Converted to the same white or black.

The image processing method according to the twentieth aspect of the present invention is the image processing method according to the thirteenth aspect, wherein in determining whether or not the target pixel is included in a halftone portion, the image processing method determines whether the target pixel is a continuous pixel. If the number of white pixels input as a pixel is equal to or less than the number of pixels existing between the black portions of the dither, or the number of black pixels continuously input as the pixel of interest forms the black portion of the dither When the number of pixels is equal to or less than the number of pixels to be processed, the pixel group of interest is determined to be included in the halftone portion.

According to the twentieth aspect of the present invention, based on the number of continuously input white pixels or the number of continuously input black pixels, the target pixel is a white portion of dither or a dithered portion. It is determined whether or not it is included in the black portion of.

The storage medium according to the twenty-first aspect of the present invention stores a program for causing a computer to execute the method according to the twelfth to twentieth aspects, so that the program becomes machine-readable. ,
The operations of claims 12 to 20 can be realized by a computer.

[0048]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Preferred embodiments of the image processing apparatus according to the present invention will be described in detail.

FIG. 1 is a block diagram functionally showing the configuration of the image processing apparatus according to the embodiment of the present invention. The image processing apparatus includes an image data control unit 100, an image reading unit 101, an image memory control unit 10
2. Image processing unit 103 and image writing unit 1
04. The image reading unit 101, the image memory control unit 102, the image processing unit 103, and the image writing unit 104 are connected to the image data control unit 100.

The image reading unit 101 is a unit for reading a document and obtaining image data. The image memory control unit 102 is a unit for writing or reading image data to or from an image memory for storing image data. The image processing unit 103 is a unit for performing image processing such as processing and editing on image data. Image writing unit 1
Reference numeral 04 denotes a unit for writing image data on transfer paper or the like.

(Image Data Control Unit 100) The processing performed by the image data control unit 100 includes, for example, the following processing (1) to (11).

(1) Data compression processing (primary compression) for improving the data bus transfer efficiency. (2) Transfer processing of primary compressed data to image data. (3) Image synthesis processing (image data from a plurality of units can be synthesized, and also includes synthesis on a data bus). (4) Image shift processing (shifting of an image in the main scanning and sub-scanning directions). (5) Image area extension processing (the image area can be enlarged to the periphery by an arbitrary amount). (6) Image scaling processing (for example, 50% or 200%
Fixed magnification). (7) Parallel bus interface processing. (8) Serial bus interface processing (interface with a process controller 211 described later). (9) Format conversion processing of parallel data and serial data. (10) Interface processing with the image reading unit 101. (11) Interface processing with the image processing unit 103.

(Image Reading Unit 101) As the processing performed by the image reading unit 101, for example,
There are the following processes (1) to (5).

(1) Reading process of the original reflected light by the optical system. (2) Conversion into an electric signal in the light receiving element. (3) Digitization processing in the A / D converter. (4) Shading correction processing (processing for correcting illuminance distribution unevenness of the light source). (5) Scanner γ correction processing (processing for correcting the density characteristic of the reading process).

(Image Memory Control Unit 102) The processing performed by the image memory control unit 102 includes, for example, the following processing (1) to (10).

(1) Interface control processing with the system controller. (2) Parallel bus control processing (interface control processing with the parallel bus). (3) Network control processing. (4) Serial bus control processing (control processing of a plurality of external serial ports). (5) Internal bus interface control processing (command control processing with the operation unit). (6) Local bus control processing (ROM, RAM, font data access control processing for activating the system controller). (7) Memory module operation control processing (memory module write / read control processing, etc.). (8) Processing for controlling access to memory modules (processing for arbitrating memory access requests from a plurality of units). (9) Data compression / expansion processing (processing for reducing the amount of data for effective use of memory). (10) Image editing processing (data clear in memory area,
Image data rotation processing, memory image synthesis processing, etc.).

(Image processing unit 103) As the processing performed by the image processing unit 103, for example,
There are the following processes (1) to (14).

(1) Shading correction processing (processing for correcting uneven illuminance distribution of the light source). (2) Scanner γ correction processing (processing for correcting the density characteristic of the reading process). (3) MTF correction processing. (4) Smoothing processing. (5) Arbitrary scaling processing in the main scanning direction. (6) Density conversion (γ conversion processing: corresponding to density notch). (7) Simple multi-value processing. (8) Simple binarization processing. (9) Error diffusion processing. (10) Dither processing. (11) Dot arrangement phase control processing (rightward dot, leftward dot). (12) Isolated point removal processing. (13) Image area separation processing (color determination, attribute determination, adaptive processing). (14) Density conversion processing.

(Image Writing Unit 104) As processing performed by the image writing unit 104, for example,
There are the following processes (1) to (4).

(1) Edge smoothing processing (jaggy correction processing). (2) Correction processing for dot rearrangement. (3) Image signal pulse control processing. (4) Format conversion processing between parallel data and serial data.

(Hardware Configuration of Digital MFP)
Next, a hardware configuration when the image processing apparatus according to the embodiment forms a digital multifunction peripheral will be described. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the image processing apparatus according to the embodiment.

The image processing apparatus according to the embodiment includes a reading unit 201, a sensor board unit 202,
Image data control unit 203, image processor 20
4. It has a video data control unit 205 and an imaging unit (engine) 206. The image processing apparatus includes a serial bus 210, a process controller 2
11, a RAM 212 and a ROM 213.

The reading unit 201, the sensor board
Unit 202, image data control unit 203, video / data control unit 205, imaging unit (engine) 206,
The process controller 211, the RAM 212, and the ROM 213 are mutually connected via the serial bus 210. The image processor 204 is connected to the image data control unit 203 and the video data control unit 205.

Further, the image processing apparatus is provided with a parallel bus 22.
0, image memory access control unit 221, memory
Module 222 and facsimile control unit 22
4 is provided. Image memory access control unit 22
1. The facsimile control unit 224 and the image data control unit 203 are mutually connected via a parallel bus 220.

The memory module 222 is connected to the image memory access control unit 221. The image memory access control unit 221 is connected to an external PC (personal computer) 223. The facsimile control unit 224 is connected to a public line (PN) 225.

The image processing device includes a system controller 231, a RAM 232, a ROM 233, and an operation panel 234. The system controller 231, the RAM 232, the ROM 233, and the operation panel 234 are connected to the image memory access control unit 221.

Here, the components 201 to 20 shown in FIG.
6, 221, 222 and each unit 100- shown in FIG.
The correspondence relationship with the 104 will be described. Reading unit 2
01 and the sensor board unit 202 have a function as the image reading unit 101 (see FIG. 1). Further, the image data control unit 203 has a function as the image data control unit 100 (see FIG. 1).
Further, the image processing processor 204 has a function as the image processing unit 103 (see FIG. 1).

The video data control unit 205 and the image forming unit (engine) 206 include the image writing unit 1
04 (see FIG. 1). The image memory access control unit 221 and the memory module 222 have a function as the image memory control unit 102 (see FIG. 1).

Next, the contents of each component of the image processing apparatus shown in FIG. 2 will be described. Although not shown, the reading unit 201 for optically reading an original includes, for example, a lamp, a mirror, and a lens. Reading unit 2
Reference numeral 01 denotes a configuration in which reflected light of lamp irradiation on a document is condensed on a light receiving element by a mirror and a lens.

The light receiving element is, for example, a CCD (Charge).
It is composed of a Coupled Device (charge coupled device). CCD is a sensor board unit 20
2 is installed. The CCD converts a light signal reflected by the original into an electric signal. Sensor board unit 2
Reference numeral 02 converts the image data converted into an electric signal into a digital signal and outputs the digital signal to the image data control unit 203.

The image data control unit 203 controls transmission of image data between the functional device (processing unit) and the data bus. An image data control unit 203 is a system controller that controls the data transfer between the sensor board unit 202, the parallel bus 220, and the image processing processor 204, the process controller 211 for the image data, and the overall control of the image processing apparatus. 231 is performed.

The RAM 212 is used as a work area of the process controller 211. ROM 213
Stores a boot program of the process controller 211 and the like.

The image data control unit 203 transfers the image data sent from the sensor board unit 202 to the image processor 204. The image processor 204 corrects signal degradation (referred to as signal degradation of a scanner system) due to quantization into an optical system and a digital signal. In addition, image processing processor 2
Reference numeral 04 performs image quality processing for converting luminance data from the CCD of the sensor board unit 202 into area gradation.

The image memory access control unit 221 comprises:
It controls writing or reading of image data to / from the memory module 222. In addition, image memory
The access control unit 221 controls the operation of each component connected to the parallel bus 220. The RAM 232 is used as a work area of the system controller 231. ROM 233 is the system controller 231
And the like are stored.

The operation panel 234 is for inputting processing to be performed by the image processing apparatus. For example,
The type of processing (copying, facsimile transmission, image reading, printing, etc.), the number of processings, and the like are input via the operation panel 234. Thereby, the input of the image data control information is performed.

Next, an example of a data flow in the image processing apparatus having the configuration shown in FIG. 2 will be described. In the reading unit 201 and the sensor board unit 202, the original is optically read and converted into an electric signal. The image data converted into the electric signal is converted into a digital signal in the sensor board unit 202 and sent to the image processor 204 via the image data control unit 203.

In the image processor 204, correction processing of signal deterioration (referred to as signal deterioration of a scanner system) due to quantization of image data into an optical system and a digital signal is performed. After the correction processing, the image data is temporarily stored in the memory module 222 via, for example, the image data control unit 203 and the image memory access control unit 221. The stored image data is transferred again to the image processor 204, where the CC of the sensor board unit 202 is
An image quality process for converting the luminance data by D into an area gradation is performed.

The image data on which the image quality processing has been completed is transferred to the video data control section 205, where the post-processing relating to the dot arrangement and the pulse control for reproducing the dots are performed on the signal changed to the area gradation. Is performed. Thereafter, the image is output as a reproduced image on transfer paper in the image forming unit 206.

In the flow of image data, the functions of the digital multi-function peripheral are realized by the bus control by the parallel bus 220 and the image data control unit 203. In the facsimile transmission function, the read image data is subjected to image processing by the image processor 204 and transferred to the facsimile control unit 224 via the image data control unit 203 and the parallel bus 220. The facsimile control unit 224 performs data conversion to a communication network, and transmits the data to a public line (PN) 225 as facsimile data.

On the other hand, with respect to the received facsimile data, facsimile control unit 224 converts line data from public line (PN) 225 into image data. The converted image data is transferred to the image processor 204 via the parallel bus 220 and the image data control unit 203. Image processing processor 204
Transfers image data to the video data control unit 205 without performing special image quality processing. The video data control unit 205 performs dot rearrangement and pulse control on the image data. Then, the imaging unit 2
At 06, a reproduced image is formed on the transfer paper.

In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function, and a printer output function operate in parallel, allocation of the right to use the reading unit 201, the imaging unit 206, and the parallel bus 220 to the job is performed by the system. It is controlled by the controller 231 and the process controller 211.

The process controller 211 controls the flow of image data, and the system controller 231
Controls the entire system and manages the activation of each resource. In addition, the function selection of the digital multi-function peripheral is selectively inputted on the operation panel 234 of the operation unit, and the processing contents such as the copy function and the facsimile function are set.

The system controller 231 and the process controller 211 communicate with each other via the parallel bus 220, the image data control unit 203, and the serial bus 210. Specifically, communication between the system controller 231 and the process controller 211 is performed by performing a data format conversion for a data interface between the parallel bus 220 and the serial bus 210 in the image data control unit 203.

FIG. 3 is a block diagram for explaining a flow of data related to gradation conversion of the image processing apparatus according to the embodiment, and FIG. 4 is a diagram showing a main part thereof. When the original is read by the scanner (reading unit 201), for example, the main scanning sub-scanning Ndpi 8 bits 256
Gradation image data is obtained.

This image data is subjected to shading correction by a shading correction block 51, a main scanning electric scaling block 52 and a filter processing block 53, respectively.
After being subjected to main scanning electrical scaling and filter processing, it is sent to the gradation processing block 54. Gradation processing block 54
In this example, simple binary quantization, binary dither, binary error diffusion, or the like for quantizing input 8-bit data with a fixed threshold is performed according to the image quality mode.

The printer controller 55 generates Ndpi 1-bit 2-tone data. Data generated by either the gradation processing block 54 or the printer controller 55 is input to the gradation conversion block 56. The Ndpi 1-bit 2-tone image data input to the gradation conversion block 56 is Ndpi
The image data is converted into M gradation image data and output. Ndpi
The output image data of M gradation is sent to a plotter capable of writing multi-value data, where an image is formed. These blocks are used by the image processor 20
4 is implemented.

FIG. 5 is a block diagram showing a configuration of the image processor 204. The processor includes a plurality of sets of input / output ports 31a, 31b, 31c for inputting and outputting data to and from the processor array 30.
31d and 31e (VD0 to VD4), and the input or output can be set arbitrarily. Further, a local memory group 32 including a plurality of RAMs is provided.

The local memory group 32 is used as a buffer memory for storing input data or data for output. The input / output data is controlled by the buffer memory at the interface with the outside. The local memory group 32 is connected to a plurality of memory control units 33. Memory control unit 33
Controls the memory area to be used and the path of the data path.

The image data stored in the local memory group 32 is subjected to various processes in the processor array 30, and the output result is stored again in the local memory group 32. The processing procedure of the processor, parameters for the processing, and the like are exchanged between the program RAM and the data RAM. Program RAM or data RA
The contents of M are downloaded from the process controller 211 (see FIG. 2) via the serial interface. Alternatively, the process controller 21
1 reads the contents of the data RAM and monitors the progress of the processing.

When the contents of the processing are changed or the processing form required by the system is changed, the contents of the program RAM and the data RAM referred to by the processor array 30 are updated. This image processor 2
In the input / output port 31, image data of a predetermined length is input / output port 31.
a, 31b, 31c, 31d, and 31e, input from any of the ports, and perform desired image processing by the processor array 30 based on the control of the program.
The processed data is transferred to another input / output port 31a, 31b, 3
An operation of outputting from 1c, 31d, and 31e is possible.

In FIG. 5, reference numeral 34 denotes a memory controller group, reference numeral 35 denotes a bus switch group, reference numeral 36 denotes an SCI group, and reference numeral 37 denotes an interrupt controller. Reference numeral 38 denotes a timer, reference numeral 39 denotes a ROM boot external access, reference numeral 40 denotes a host interface, and reference numeral 41 denotes a clock generator.

FIG. 6 is a block diagram showing the flow of data in the gradation conversion block 56. The gradation conversion block 56 includes a halftone determination unit 61 and an acquisition unit 6
2, a pattern determining means 63 and a converting means 64 are provided. The halftone determination unit 61 determines whether the pixel of interest, which is a pixel to be processed, is included in a halftone portion, a character portion such as a character or a line, or a background portion including white pixels.

The judgment operation of the halftone judgment means 61 will be described later. The acquiring unit 62 acquires an image pattern of a 3 × 3 matrix including a target pixel and eight pixels surrounding the target pixel. Specifically, two FIFO memories are allocated to the RAM in the image processor 204. Then, a 3 × 3 matrix is generated by accumulating the Ndpi 2 value main scanning data in the FIFO memory.

The pattern judging means 63 compares the 3 × 3 matrix image pattern acquired by the acquiring means 62 with a 3 × 3 matrix sample pattern prepared in advance, and determines whether the two patterns match. Make a decision. This determination is performed by a dedicated command for pattern matching prepared in the image processor 204. The sample pattern includes a step pattern 71, an oblique line pattern 72, a horizontal line pattern 73, and a vertical line pattern 74.
These sample patterns are stored in ROM or data R
It is read from the storage means 7 such as AM.

A step pattern 71, an oblique line pattern 72,
The horizontal line pattern 73 and the vertical line pattern 74 will be described later. The conversion means 64 converts the Ndpi one pixel 1 bit binary (two gradations) image data input to the gradation conversion block 56 based on the control signals sent from the halftone judgment means 61 and the pattern judgment means 63. And Ndp
The image data is converted into image data of i-pixel M value (M gradation).

FIG. 7 is a schematic diagram showing the step pattern 71. As the step pattern 71, for example, 9 shown in FIG.
There are different patterns. In FIG. 7, * indicates a target pixel, and a number indicates a value of the pixel at M gradation (the same applies to FIG. 8). One pixel represents, for example, 600 dpi1 pixel.

Therefore, for example, when converting 600 dpi / pixel binary image data to 600 dpi / pixel 5 pixel image data, all white is set to zero and all black is associated with 4. If the 3 × 3 matrix pattern centered on the target pixel matches any of the patterns shown in FIG. 7, the conversion unit 64 assigns a dot smaller than a full 600 dpi dot to the target pixel. In other words, the value of the target pixel in the M gradation is originally zero, but is set to a value between zero and four, for example, two. By performing the smoothing process in this way, the step portion of the image is reduced, and a smooth image is obtained.

FIG. 8 is a schematic diagram showing a line pattern composed of an oblique line pattern 72, a horizontal line pattern 73, and a vertical line pattern 74. As the diagonal line pattern 72, for example, there are four types of patterns shown in FIG. When the pattern of the 3 × 3 matrix centering on the target pixel matches any one of the oblique line patterns 72 shown in FIG.
The conversion means 64 sets the value of the target pixel in the M gradation to zero and 4
, For example, 1. By doing this,
The diagonal lines are originally easily broken, but the diagonal lines can be reproduced without interruption.

It is also assumed that the electrophotographic engine tends to reproduce vertical lines thicker than horizontal lines, for example. In this case, if the pattern of the 3 × 3 matrix centered on the target pixel matches the vertical line pattern 74 shown in FIG. Convert to low, for example, 3. However, even if the pattern of the 3 × 3 matrix centered on the target pixel matches the horizontal line pattern 73 shown in FIG. The reverse is true if the electrophotographic engine tends to reproduce horizontal lines thicker than vertical lines, for example.

By performing this for all pixels having the same pattern, it is possible to reproduce the vertical line and the horizontal line so that they have the same thickness. It should be noted that whether to lower the gradation of the pixel of interest when matching with the horizontal line pattern 73 or to lower the gradation of the pixel of interest when matching with the vertical line pattern 74 is determined by the electrophotographic engine. Is determined according to the characteristics of

Next, the determination operation in the halftone determination means 61 will be described. Here, the continuity of pixels is used as a feature amount in order to separate a halftone portion formed by dither or error diffusion from a character portion such as a character or a line. In order to find the continuity of black pixels, in the present embodiment, for example, a detector including a state machine operating according to the state transition diagram shown in FIG. 9 is provided in the halftone determination unit 61. SIM
Since it is inefficient for the D processor to operate sequentially in the main scanning direction, it is operated here in the sub-scanning direction.

First, when reading a document, the process starts from the background state. At this time, the smoothing processing is on (smtO
N). In this state, while the input pixel is white, the background state is maintained, and if the input pixel is black, the state changes to the character state. In the state of the character, the smoothing process is on (smtON). If the input pixel is white in the character state, the state transits to the dither (white) state. In the dither (white) state, the smoothing processing is turned off (smtOFF).

When the state transits to the dither (white) state,
The value of the internal counter wcnt is cleared to zero.
If the next input pixel is white, the counter wcn
The value of t is incremented. The dither (white) state is maintained as long as the value of the counter wcnt is smaller than the dither interval, that is, the number of pixels dwid existing between the black portions of the dither. When the value of the counter wcnt becomes larger than the dither interval dwid, the state transits to the background state.

On the other hand, when a black pixel is input in the dither (white) state, the state transits to the dither (black) state. In the dither (black) state, the smoothing processing is off (smtOFF). When the state transits to the dither (black) state, the value of the internal counter bcnt is cleared to zero.

If the next input pixel is black, the counter b
Increment the value of cnt. Counter bcnt
Is smaller than the size dsize of the black portion of the dither, the dither (black) state is maintained. Counter bc
When the value of nt becomes larger than the dither size dsize, the state transits to the character state. Then, the state of the character is maintained until a white pixel is input, and when a white pixel is input, the state transits to a dither (white) state.

FIG. 10 is a schematic diagram showing an implementation of the above-described state machine in the image processor 204. FIG. 11 is a block diagram illustrating an arithmetic unit of the SIMD processor in which the above-described state machine is mounted. PE is a processor element 81,
This corresponds to the ALU 82 in FIG.

Each ALU 82 is provided with, for example, 20 8-bit registers (REG) 83,
There are 24 sets. Signals representing states and counters wcnt and bcn are assigned to these registers 83. Since the state is different for each pixel in the main scanning direction, the state is maintained in the main scanning unit as described above, and the on / off determination of the smoothing processing is performed while performing the scanning.

Next, an image processing method according to an embodiment of the present invention will be described. FIG. 12 is a flowchart illustrating an example of the image processing method according to the embodiment of the present invention.

First, an input pixel of Ndpi one pixel 1 bit binary is set as a target pixel, and the halftone determining means 61 determines whether or not the target pixel is included in the halftone portion (step S1). Regarding the judgment operation at this time,
This is as described with reference to FIG. When the target pixel is not included in the halftone portion (Step S1: No),
That is, when the target pixel is included in a character portion such as a character or a line or a background portion, the halftone determination unit 61
Is supplied with a control signal for generating a 3 × 3 matrix.

The acquisition means 62 is supplied with 1-bit binary image data of Ndpi one pixel. Based on the data, the acquisition means 62 generates a 3 × 3 matrix by nine pixels including the pixel of interest. (Step S2). The data of the generated image pattern of the matrix is sent to the pattern determination unit 63.

The pattern judging means 63 acquires the sample pattern from the storage means 7 by reading mucos (step S3), and compares the pattern of the 3 × 3 matrix with the sample pattern (pattern matching) (step S3).
4). The result of the comparison is supplied from the pattern determination means 63 to the conversion means 64. The conversion means 64 is supplied with Ndpi image data of one bit and one bit binary.

As a result of the comparison, when the pattern of the 3 × 3 matrix matches the pattern of the oblique line (step S5), as described with reference to FIG. Convert to 1. In the case of an electrophotographic engine in which vertical lines tend to be emphasized, if the pattern is compared and the 3 × 3 matrix pattern matches the horizontal line pattern, the conversion unit 64 changes the gradation of the target pixel. If it is 4, and the pattern matches the pattern of the vertical line, the conversion means 64 converts the gradation of the target pixel to, for example, 3.

In the case of an electrophotographic engine in which horizontal lines tend to be emphasized, if the 3 × 3 matrix pattern matches the vertical line pattern, the conversion means 64 sets the gradation of the pixel of interest to 4 as it is. If the pattern coincides with the horizontal line pattern, the conversion means 64 converts the gradation of the pixel of interest to, for example, 3 (step S6).

As a result of the comparison in step S4, 3 ×
If the three-matrix pattern matches the step pattern (step S5), as described with reference to FIG. 7, the conversion unit 64 converts the gradation of the target pixel to, for example, 2 (step S8). Further, as a result of the comparison in step S4, if the pattern of the 3 × 3 matrix does not match any of the patterns (step S5), the conversion unit 64 converts the gray level of the target pixel in the M gray level into Ndpi one pixel 1 A gradation corresponding to the gradation when the bit is binary is set (step S7). That is, when M = 5, if the gradation at the time of Ndpi one pixel 1 bit binary is zero, the gradation of the Ndpi one pixel M value is also zero, and the gradation at the time of Ndpi one pixel 1 bit binary is zero. If it is 1, the gradation of the M value of one Ndpi pixel is set to 4.

On the other hand, if the result of the determination in step S1 indicates that the target pixel is not included in the halftone portion, the gray scale in the M gray scale of the target pixel is changed to the gray scale when the Ndpi pixel is 1 bit binary. Is supplied from the halftone determination unit 61 to the conversion unit 64.
As a result, the gray scale of the target pixel in the M gray scale is set to a gray scale corresponding to the gray scale when Ndpi is one bit per pixel, as in step S7 (step S10). The above processing is repeated until the processing is completed for all the pixels (steps S9, S11, S12). When the processing is completed for all the pixels, the gradation conversion processing is completed.

According to the above-described embodiment, when converting 1-bit 1-bit binary input image data into 1-pixel M-value image data, 3 × 9 pixels including the target pixel are used.
When the three-matrix pattern matches a step pattern prepared as a sample in advance, the white pixels in the step forming part are converted into gray levels between white and black.
The image of the step can be reproduced more smoothly.

Even in a copying machine or a printer having a high-density writing device, a smoothing process for making an image smoother is effective for improving the image quality. Conventionally, such a smoothing process has been realized by dedicated hardware. . However, since a suitable algorithm changes according to the writing density and characteristics of the plotter, middleware using a DSP or the like is desired. According to the present embodiment, smoothing processing can be performed by middleware using a SIMD processor having high performance.

According to the above-described embodiment, when converting 1-bit binary image data of one pixel to M-value image data of one pixel, 3 × 9 pixels including the target pixel are used. If the pattern of the three matrices matches the oblique line pattern prepared as a sample in advance,
Since the white pixels around the oblique line are converted into gray levels between white and black, the oblique line can be reproduced without interruption.

According to the above-described embodiment, when converting 1-bit 1-bit binary input image data into 1-pixel M-value image data, 3 × 9 pixels including the target pixel are used. A vertical line pattern (or horizontal line pattern) in which three matrix patterns are prepared in advance as a sample
, The black pixels constituting the vertical line (or horizontal line) are converted into gray levels between white and black, so that the vertical line and horizontal line can be reproduced so as to have the same line width. it can.

In general, as a requirement for the printing quality of a printer, it is required to reproduce a line segment of any inclination with the same thickness. However, when the output form is an electronic photograph or the like, a vertical line and a horizontal line are drawn. Even when drawing is performed with the same intensity, the thickness of the output image is often not uniform. In such a case, it is necessary to control the thickness of the line according to the angle. However, according to the present embodiment, the thickness of the line is controlled by controlling the gradation of the vertical line (or the horizontal line) as described above. Can be the same.

Further, according to the above-described embodiment, when the pixel of interest is included in the halftone portion, gradation conversion processing is not performed when the pixel of interest coincides with a step pattern or a line pattern. Character portion can be reproduced smoothly, and a halftone image with good gradation can be reproduced. Conventionally, there has been a case where the gradation property is deteriorated in a halftone image composed of independent pixels such as an image after dithering and error diffusion by a smoothing process. However, according to the present embodiment, in a halftone image, Degradation of gradation can be avoided.

In the above, the present invention can be variously modified. For example, the gradation value in the M gradation of the target pixel when the 3 × 3 matrix pattern matches the step pattern, the oblique line pattern, the vertical line pattern, or the horizontal line pattern is not limited to the above-described example.

The image processing method described in the present embodiment is realized by executing a prepared program on a computer. This program is
Hard disk, floppy (registered trademark) disk, C
The program is recorded on a computer-readable recording medium such as a D-ROM, an MO, and a DVD, and is executed by being read from the recording medium by the computer. Further, this program can be distributed via the recording medium and as a transmission medium via a network such as the Internet.

[0124]

As described above, according to the first aspect of the present invention, there is provided an apparatus for converting one-bit, one-bit, binary input image data into one-pixel M-value image data. An acquisition unit for acquiring a pattern of a 3 × 3 matrix pixel group composed of eight pixels surrounding the target pixel, and one or more sample patterns prepared in advance for the 3 × 3 matrix pixel group Storage means for storing, a determination means for determining whether or not the pattern of the 3 × 3 matrix pixel group matches the sample pattern; and a determination of whether the pattern of the 3 × 3 matrix pixel group is a specific sample of the sample pattern. And converting means for converting the gradation of the pixel of interest to a value corresponding to the specific sample pattern when the pattern matches the pattern. Therefore, the gradation of the target pixel of one bit and one bit of one pixel is represented by the M value of one pixel in accordance with the sample pattern in which the pattern of the 3 × 3 matrix including the target pixel and eight pixels surrounding the target pixel matches. Is converted to a key.
An effect is obtained that an image processing device capable of converting one bit and one bit binary value to one pixel M value is obtained.

According to the second aspect of the present invention, in a device for converting one-bit one-bit binary image data into one-pixel M-value image data, the pixel of interest is included in a halftone portion. Halftone determination means for determining whether or not the target pixel is not included in the halftone portion,
Acquiring means for acquiring a pattern of a 3 × 3 matrix pixel group composed of the target pixel and eight pixels surrounding the target pixel; and 1 or 2 prepared in advance for the 3 × 3 matrix pixel group Storage means for storing the above sample patterns, pattern determination means for determining whether or not the pattern of the 3 × 3 matrix pixel group matches the sample pattern; And converting means for converting the gradation of the target pixel into a value corresponding to the specific sample pattern when the pattern matches the specific sample pattern. Therefore, when the pixel of interest is a background portion or a character portion, the gradation of the pixel of interest having one bit per pixel and a pattern of a 3 × 3 matrix composed of eight pixels surrounding the pixel of interest match the pixel of interest. Since the gradation is converted into the gradation of one pixel M value according to the sample pattern, there is an effect that an image processing apparatus capable of converting one bit 1 pixel binary value into one pixel M value is obtained.

According to a third aspect of the present invention, in the first or second aspect of the invention, when the specific sample pattern is a pattern corresponding to a step portion of an image, the converting means sets the target The configuration is such that the gradation of the pixel is converted to a value between zero and the maximum. Therefore, when the pattern of the 3 × 3 matrix including the pixel of interest matches the sample pattern of the stepped portion, the gradation of the pixel of interest having one bit and two bits per pixel is between the white and black in the gradation of one pixel M value. Since the conversion is performed so as to obtain the gradation, there is an effect that an image processing apparatus capable of more smoothly reproducing the image of the step portion can be obtained.

According to the invention described in claim 4, in the invention described in claim 1 or 2, when the specific sample pattern is a pattern corresponding to a diagonal line of an image, the conversion means sets the target The configuration is such that the gradation of the pixel is converted to a value between zero and the maximum. Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the sample pattern of the oblique line, the gradation of the target pixel of one bit and one bit per pixel is between the white and black in the gradation of one pixel M value. Since the conversion is performed so as to obtain the gradation, there is an effect that an image processing apparatus capable of reproducing an image of an oblique line without interruption is obtained.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, when the specific sample pattern is a pattern corresponding to a vertical line of an image, the converting means sets the target The configuration is such that the gradation of the pixel is converted to a value between zero and the maximum. Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the sample pattern of the vertical line, the gray level of the target pixel of one bit and one bit per pixel is between the white and black in the gray level of one pixel M value. Since the conversion is performed so that the gradation is obtained, an image processing apparatus capable of reproducing the vertical line and the horizontal line with the same width in an electrophotographic engine in which the vertical line tends to be emphasized rather than the horizontal line can be obtained. Play.

According to the invention described in claim 6, in the invention described in claim 1 or 2, when the specific sample pattern is a pattern corresponding to a horizontal line of an image, the converting means sets the pixel of interest to the target pixel. Is converted to a value between zero and the maximum. Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the horizontal line sample pattern, the gradation of the target pixel of one bit and one bit per pixel is the gradation between white and black in the gradation of one pixel M value. Is converted so that the horizontal line is more emphasized than the vertical line. In an electrophotographic engine in which the horizontal line tends to be emphasized more than the vertical line, an image processing apparatus capable of reproducing the vertical line and the horizontal line with the same width is obtained. .

According to the invention of claim 7, in the invention of claim 1 or 2, if the pattern of the 3 × 3 matrix pixel group does not match the sample pattern, the conversion means The tone corresponding to the M value of one pixel of the target pixel is set to a value corresponding to the tone of the original binary value of one pixel. Therefore, if the pattern of the 3 × 3 matrix including the target pixel does not match the sample pattern, the grayscale of the target pixel of one bit and one binary value is the same as the original white or black even in the grayscale of one pixel M value. Since the pixel is not required to be converted between white and black in the gray level of one pixel M value, the original gray level of one bit and one bit of one pixel is directly converted to the gray level of one pixel M value. In this case, it is possible to obtain an image processing apparatus capable of converting the image into white or black gradation.

According to an eighth aspect of the present invention, in the second aspect of the invention, when the target pixel is included in a halftone portion, the conversion means sets one pixel M value of the target pixel. Is set to a value corresponding to the gradation in the original binary value of one pixel. for that reason,
When the pixel of interest is included in the halftone portion, the grayscale of the pixel of interest having one bit and two bits per pixel is converted to the same white or black as the original in the grayscale of one pixel M value. An effect is obtained that an image processing device that can reproduce more smoothly and that can reproduce without degrading the gradation of the image of the halftone portion is obtained.

According to a ninth aspect of the present invention, in the second aspect of the present invention, the halftone determining means determines that the number of white pixels continuously input as the pixel of interest is a black dither. If the number of black pixels continuously input as the target pixel is equal to or less than the number of pixels existing between the portions, or if the number of black pixels continuously input as the target pixel is equal to or less than the number of pixels constituting the black portion of the dither, the target pixel group is The configuration is such that it is determined to be included in the halftone section. Therefore, based on the number of continuously input white pixels or the number of continuously input black pixels, the target pixel is included in the white portion of dither, the black portion of dither, or not included at all. Therefore, it is possible to obtain an image processing apparatus that can easily identify a halftone portion, a character portion, and a background portion.

According to the tenth aspect of the present invention,
In the invention described in claim 1, the acquisition unit, the determination unit, and the conversion unit are configured by a SIMD type processor. Therefore, there is an effect that an image processing apparatus can be obtained in which the gradation conversion processing from one-bit one-bit binary to one-pixel M-value can be performed by middleware including a SIMD type processor having high performance. .

According to the eleventh aspect of the present invention,
In the invention described in claim 2, the halftone determination unit, the acquisition unit, the pattern determination unit, and the conversion unit are configured by a SIMD type processor. For this reason, the gradation conversion processing from one-bit one-bit binary to one-pixel M-value is performed by SIMD with high performance.
There is an effect that an image processing apparatus that can be performed by middleware including a processor of a type is obtained.

Further, according to the twelfth aspect of the present invention,
In converting one-bit one-bit binary input image data into one-pixel M-value image data, a pattern of a pixel of interest and a 3 × 3 matrix pixel group composed of eight pixels surrounding the pixel of interest includes: Judging whether or not it matches one or more sample patterns prepared in advance for the 3 × 3 matrix pixel group;
Converting the gradation of the target pixel into a value corresponding to the specific sample pattern when the pattern of the three-matrix pixel group matches a specific sample pattern of the sample patterns. . Therefore, the gradation of the target pixel of one bit and one bit is determined by the M value of one pixel according to the sample pattern in which the pattern of the 3 × 3 matrix including the target pixel and the eight pixels surrounding the target pixel matches. Since the image data is converted to a gray scale, there is an effect that an image processing method capable of converting one bit 1 bit binary value to one pixel M value is obtained.

According to the thirteenth aspect of the present invention,
A step of determining whether or not the target pixel is included in the halftone portion when converting the input image data of one bit and one bit binary into image data of one pixel M value; If not, the target pixel and 3 × 3 pixels constituted by eight pixels surrounding the target pixel
Determining whether the pattern of the matrix pixel group matches one or more sample patterns prepared in advance for the 3 × 3 matrix pixel group;
Converting the tone of the pixel of interest into a value corresponding to the specific sample pattern when the pattern of the 3 × 3 matrix pixel group matches a specific sample pattern of the sample patterns. Has become. Therefore, when the target pixel is a background portion or a character portion, the gradation of the target pixel of one bit per pixel is 3 × 3 which is composed of the target pixel and eight pixels surrounding the target pixel.
Since the conversion is performed to the gradation of one pixel M value according to the sample pattern in which the patterns of the three matrices match, one pixel
An effect is obtained that an image processing method capable of converting a binary value into an M value per pixel is obtained.

According to the fourteenth aspect of the present invention,
The invention according to claim 12 or 13, wherein when the specific sample pattern is a pattern corresponding to a step portion of an image, a gradation of the pixel of interest is converted into a value between zero and a maximum. I have. Therefore, when the pattern of the 3 × 3 matrix including the pixel of interest matches the sample pattern of the stepped portion, the gradation of the pixel of interest having one bit and two bits per pixel is between the white and black in the gradation of one pixel M value. Since the conversion is performed so as to obtain the gradation, there is an effect that an image processing method capable of more smoothly reproducing the image of the step portion can be obtained.

According to the fifteenth aspect of the present invention,
The invention according to claim 12 or 13, wherein when the specific sample pattern is a pattern corresponding to a diagonal line of an image, a gradation of the pixel of interest is converted into a value between zero and a maximum. I have. Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the sample pattern of the oblique line, the gradation of the target pixel of one bit and one bit per pixel is between the white and black in the gradation of one pixel M value. Since the conversion is performed so as to obtain the gradation, there is an effect that an image processing method capable of reproducing an image of an oblique line without interruption is obtained.

According to the sixteenth aspect of the present invention,
The invention according to claim 12 or 13, wherein when the specific sample pattern is a pattern corresponding to a vertical line of an image, a gradation of the pixel of interest is converted to a value between zero and a maximum. I have. Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the sample pattern of the vertical line, the gray level of the target pixel of one bit and one bit per pixel is between the white and black in the gray level of one pixel M value. Since the conversion is performed so that the gradation is obtained, the image processing method that can reproduce the vertical line and the horizontal line with the same width in an electrophotographic engine in which the vertical line tends to be emphasized rather than the horizontal line is obtained. Play.

According to the seventeenth aspect of the present invention,
The invention according to claim 12 or 13, wherein when the specific sample pattern is a pattern corresponding to a horizontal line of an image, the gradation of the pixel of interest is converted to a value between zero and the maximum. . Therefore, when the pattern of the 3 × 3 matrix including the target pixel matches the horizontal line sample pattern, the gradation of the target pixel of one bit and one bit per pixel is the gradation between white and black in the gradation of one pixel M value. Since the image data is converted so that the horizontal lines are emphasized rather than the vertical lines, an image processing method capable of reproducing the vertical lines and the horizontal lines with the same width in an electrophotographic engine is obtained. .

According to the eighteenth aspect of the present invention,
In the invention according to claim 12 or 13, the 3 ×
When the pattern of the three-matrix pixel group does not match the sample pattern, the method further includes the step of setting the tone corresponding to one pixel M value of the target pixel to a value corresponding to the original one pixel binary value. It has become. Therefore, if the pattern of the 3 × 3 matrix including the target pixel does not match the sample pattern, the grayscale of the target pixel of one bit and one binary value is the same as the original white or black even at the grayscale of one pixel. Since the pixel is not required to be converted between white and black in the gray level of one pixel M value, the original gray level of one bit and one bit of one pixel is directly converted to the gray level of one pixel M value. In this case, it is possible to obtain an image processing method capable of converting the image into white or black gradation.

According to the nineteenth aspect,
In the invention according to claim 13, when the target pixel is included in a halftone portion, a gradation corresponding to one pixel M value of the target pixel is set to a value corresponding to two original pixel binary values. The configuration further includes a step. Therefore, when the pixel of interest is included in the halftone portion, the grayscale of the pixel of interest having one bit and one binary value is converted to the same white or black as the original in the grayscale of one pixel M value. An effect is obtained that an image processing method that can reproduce an image more smoothly and that can reproduce the image without deteriorating the gradation of an image in a halftone portion is obtained.

According to the twentieth aspect of the present invention,
In the invention according to claim 13, in determining whether or not the target pixel is included in a halftone portion, the number of white pixels continuously input as the target pixel is determined between black portions of dither. If the number of existing pixels is equal to or less than the number of existing pixels, or the number of black pixels continuously input as the pixel of interest,
When the number of pixels constituting the dither black portion is equal to or less than the number of pixels, the target pixel group is determined to be included in the halftone portion. Therefore, based on the number of continuously input white pixels or the number of continuously input black pixels, the target pixel is included in the white portion of dither, the black portion of dither, or not included at all. Therefore, it is possible to obtain an image processing method that can easily identify a halftone portion, a character portion, and a background portion.

According to the storage medium of the present invention, since the program for causing a computer to execute the method according to any one of claims 12 to 20 is recorded, the program can be machine-readable. Thus, an effect is obtained that the operations of claims 12 to 20 can be realized by a computer.

[Brief description of the drawings]

FIG. 1 is a block diagram functionally showing a configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a hardware configuration of the image processing apparatus according to the embodiment;

FIG. 3 is a block diagram for explaining a data flow relating to gradation conversion of the image processing apparatus according to the embodiment;

FIG. 4 is a diagram showing a main part of FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of a processor that performs gradation conversion of the image processing apparatus according to the embodiment;

FIG. 6 is a block diagram showing a data flow in a gradation conversion block of the image processing apparatus according to the embodiment;

FIG. 7 is a schematic diagram illustrating a step pattern prepared in the image processing apparatus according to the embodiment;

FIG. 8 is a schematic diagram illustrating a line pattern prepared in the image processing apparatus according to the embodiment;

FIG. 9 is a state transition diagram for explaining a state machine for recognizing halftone in the image processing apparatus according to the embodiment;

FIG. 10 is a schematic diagram illustrating an implementation of a state machine of the image processing apparatus according to the embodiment;

FIG. 11 is a block diagram illustrating a calculation unit of the SIMD processor in which the state machine of the image processing apparatus according to the embodiment is mounted.

FIG. 12 is a flowchart illustrating an example of an image processing method according to an embodiment of the present invention.

[Explanation of symbols]

 61 Halftone determination means 62 Acquisition means 63 Pattern determination means 64 Conversion means 100 Image data control unit 101 Image reading unit 102 Image memory control unit 103 Image processing unit 104 Image writing unit 201 Reading unit 202 Sensor board unit 203 Image data Control unit 204 Image processing processor 205 Video data control unit 210 Serial bus 211 Process controller 220 Parallel bus 221 Image memory access control unit 222 Memory module 224 Facsimile control unit 231 System controller

Claims (21)

[Claims] 1. An apparatus for converting one-bit, one-bit, binary input image data into one-pixel M-value image data, comprising: a 3 × 3 matrix comprising a target pixel and eight pixels surrounding the target pixel Acquisition means for acquiring a pattern of a pixel group; storage means for storing one or more sample patterns prepared in advance for the 3 × 3 matrix pixel group; and patterns of the 3 × 3 matrix pixel group Determining means for determining whether or not the pixel pattern matches the sample pattern; and when the pattern of the 3 × 3 matrix pixel group matches a specific sample pattern among the sample patterns, An image processing apparatus, comprising: conversion means for converting a value corresponding to a specific sample pattern into a value. 2. An apparatus for converting one-bit, one-bit, binary input image data into one-pixel M-value image data, comprising: a halftone determining unit that determines whether a target pixel is included in a halftone unit; When the target pixel is not included in the halftone portion,
Acquiring means for acquiring a pattern of a 3 × 3 matrix pixel group constituted by the target pixel and eight pixels surrounding the target pixel; and 1 or 2 provided in advance for the 3 × 3 matrix pixel group Storage means for storing two or more sample patterns; pattern determination means for determining whether the pattern of the 3 × 3 matrix pixel group matches the sample pattern; and pattern of the 3 × 3 matrix pixel group Converting means for converting the gradation of the pixel of interest into a value corresponding to the specific sample pattern, when the pattern matches a specific sample pattern of the sample patterns. 3. When the specific sample pattern is a pattern corresponding to a step portion of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum. Item 3. The image processing device according to item 1 or 2. 4. When the specific sample pattern is a pattern corresponding to an oblique line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum. Item 3. The image processing device according to item 1 or 2. 5. The method according to claim 1, wherein when the specific sample pattern is a pattern corresponding to a vertical line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum. Item 3. The image processing device according to item 1 or 2. 6. When the specific sample pattern is a pattern corresponding to a horizontal line of an image, the conversion means converts the gradation of the pixel of interest to a value between zero and a maximum. 3. The image processing device according to 1 or 2. 7. When the pattern of the 3 × 3 matrix pixel group does not match the sample pattern, the conversion unit calculates a gradation corresponding to one pixel M value of the target pixel in the original one pixel binary value. The image processing apparatus according to claim 1, wherein the value corresponds to a gradation. 8. When the pixel of interest is included in a halftone portion, the conversion means converts a gray level corresponding to one pixel M value of the target pixel to a value corresponding to a gray level in an original binary value of one pixel. The image processing apparatus according to claim 2, wherein: 9. The halftone determining means, wherein the number of white pixels continuously input as a target pixel is equal to or less than the number of pixels existing between black portions of dither, or The pixel group of interest is determined to be included in a halftone portion when the number of black pixels input as a result is equal to or less than the number of pixels forming a black portion of dither. Image processing device. 10. The image processing apparatus according to claim 1, wherein the acquisition unit, the determination unit, and the conversion unit are configured by a SIMD processor. 11. The halftone determination unit, the acquisition unit, the pattern determination unit, and the conversion unit include an SI
The image processing device according to claim 2, wherein the image processing device is configured by an MD processor. 12. A 3 × 3 matrix pixel composed of a target pixel and eight pixels surrounding the target pixel when converting one-bit / one-bit binary input image data into one-pixel M-value image data. Group pattern is 3 ×
1 prepared in advance for a 3 matrix pixel group
Or a step of determining whether or not the pixel pattern matches two or more sample patterns. If the pattern of the 3 × 3 matrix pixel group matches a specific sample pattern of the sample patterns, Converting the value to a value corresponding to the specific sample pattern. 13. Converting one-bit one-bit binary image data into one-pixel M-value image data to determine whether or not the pixel of interest is included in a halftone portion; When not included in the halftone portion, a pattern of a 3 × 3 matrix pixel group including the target pixel and eight pixels surrounding the target pixel is prepared in advance for the 3 × 3 matrix pixel group. Determining whether the selected pixel pattern matches one or more sample patterns. If the pattern of the 3 × 3 matrix pixel group matches a specific sample pattern of the sample patterns, Converting the gradation into a value corresponding to the specific sample pattern. 14. The method according to claim 12, wherein when the specific sample pattern is a pattern corresponding to a step portion of an image, the gradation of the target pixel is converted into a value between zero and a maximum. The image processing method according to 1. 15. The method according to claim 12, wherein when the specific sample pattern is a pattern corresponding to an oblique line of an image, the gradation of the target pixel is converted into a value between zero and a maximum. The image processing method according to 1. 16. The method according to claim 12, wherein when the specific sample pattern is a pattern corresponding to a vertical line of an image, the gradation of the pixel of interest is converted to a value between zero and the maximum. The image processing method according to 1. 17. The method according to claim 12, wherein when the specific sample pattern is a pattern corresponding to a horizontal line of an image, the gradation of the target pixel is converted into a value between zero and the maximum. The image processing method described in the above. 18. When the pattern of the 3 × 3 matrix pixel group does not match the sample pattern, the gray scale corresponding to one pixel M value of the target pixel corresponds to the original binary gray level of one pixel. 14. The image processing method according to claim 12, further comprising a step of setting a value. 19. When the target pixel is included in a halftone portion, the method further includes a step of setting a gradation corresponding to one pixel M value of the target pixel to a value corresponding to the original two-pixel gradation. 14. The image processing method according to claim 13, wherein: 20. In determining whether or not the target pixel is included in a halftone portion, the number of white pixels continuously input as the target pixel is determined by the number of pixels existing between black portions of dither. If the number of black pixels continuously input as the target pixel is equal to or smaller than the number of pixels constituting the black portion of the dither, the target pixel group is determined to be included in the halftone portion. 14. The image processing method according to claim 13, wherein: 21. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the method according to any one of claims 12 to 20.