JPH09179973A - Picture processor and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently execute picture processing by temporarily reducing the resolution of picture data read out from a scanner, and after executing picture processing, increasing the resolution of picture data. SOLUTION: A picture reduced by a reducing processing part 103 is reproduced at magnification equal to that of an input picture. Namely when the input picture has A4-sized picture data with 360 dpi (scanner resolution), the input picture is reduced as an A5-sized picture by the processing part 103. After executing prescribed picture processing, a resolution converting part 113 applies enlarging processing and resolution converting processing to the reduced processing to obtain an A4-sized picture with 720 dpi (printer resolution). The picture with the printer resolution converted by the converting part 113 is binarized by a binarization processing part 115 by the use of an error diffusion method. The picture processed by the processing part 115 is outputted to a recording medium by a printer 119.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing device for processing image data.

[0002]

2. Description of the Related Art A conventional image processing apparatus performs image conversion processing such as color correction processing on an image read by a scanner through a buffer memory or the like, and then performs resolution conversion when the scanner and printer do not have the same resolution. The image is copied by performing processing and outputting the image to a printer.

[0003]

However, in the above-mentioned conventional example, there is a problem that the amount of image data is very large when performing color image processing, and the image processing becomes complicated. There was also a problem that the buffer memory would increase.

Further, when the image processing is realized by software, there is a problem that the processing time becomes long.

Further, since the color components of the normal color image data are represented by RGB in the scanner and CMYK in the printer, in order to perform the same processing as the monochrome image data, the color components are three times or four times the monochrome image data, respectively. It needed processing speed and memory.

In view of the above, it is an object of the present invention to reduce the load of image processing of image data having a large amount of data and to perform image processing efficiently.

Specifically, the object is to reduce the load of image processing of color image data and efficiently perform image processing.

Another object is to reduce the capacity of the memory used for image processing of image data having a large amount of data.

[0009]

In order to solve the above problems, an image processing apparatus according to claim 1 of the present invention is an image processing apparatus for copying an image, and a reading means for reading an image and generating image data. (Corresponding to, for example, the scanner 101 in FIG. 1), and first resolution converting means (corresponding to, for example, the reduction processing unit 103 in FIG. 1) for performing resolution conversion to reduce the resolution of the image represented by the image data. An image processing unit (for example, corresponding to the color correction processing unit 105 in FIG. 1) that performs predetermined image processing on the image data whose resolution has been converted by the first resolution converting unit, and an image that has been image processed by the image processing unit. Second resolution conversion means (for example, corresponding to the resolution conversion unit 113 in FIG. 1) for performing resolution conversion for increasing the resolution of the image represented by the data, and the second
Output means (for example, corresponding to the printer 119 in FIG. 1) that visually outputs the image data whose resolution has been converted by the resolution converting means of FIG.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram for explaining an embodiment of the present invention.

In the present embodiment, an example of an image processing apparatus having two copying modes of a color mode and a monochrome mode will be described.

The block diagram shown in the upper part of FIG. 1 is an image processing unit in the color mode, 101 is a scanner for reading the image, 103 is a reduction processing unit for reducing the image, 10
A color correction processing unit 5 performs color correction on the read image according to the output characteristics of the printer.

Reference numeral 107 denotes a memory connected to the color correction processing unit for storing correction parameters suitable for the printer. Reference numeral 109 is a buffer controller for controlling the difference between the reading speed of the scanner and the recording speed of the printer, and 111 is the buffer controller 10.
9 is a buffer memory for temporarily storing image data under the control of 9.

Reference numeral 113 denotes a resolution conversion unit for converting the size of the image represented by the input image data into the resolution of the printer.
Reference numeral 115 is a binarization processing unit for binarizing the image to generate a pseudo-halftone image, 117 is a work memory used for the image processing in 115, and 119 is an image such as plain paper. A printer that outputs to a recording medium.

Next, the block diagram shown in the lower part of FIG. 1 is an image processing unit in the monochrome mode, 121 is a scanner common with 101 described above, and 123 and 125 are buffers similar to 109 and 111, respectively. A controller and a buffer.

Reference numeral 127 is the same resolution conversion unit as 113, and 129 is a binarization processing unit corresponding to the binarization processing unit 115 in the block diagram of the color mode, but the image processing method uses a fixed threshold value. Binarization (simple binarization). A printer 131 is common to the printer 119 described above.

The operation in the color mode will be described below.

First, the image read by the scanner 101 is reduced. The reduction processing unit digitally reduces the number of pixels in the main scanning by simple thinning, and performs thinning processing by subscanning under the control of the scanner.

This processing can be regarded as resolution conversion in consideration of the amount of image data.

By this processing, the color correction processing unit 10 described later is executed.
Since the amount of image data processed after 5 (the number of pixels when considering image reduction) is reduced, color correction, buffer control, etc. can be speeded up. Also, the buffer memory can be made smaller.

Next, the color correction processing unit 105 converts the RGB image data read by the scanner into CMYK data matching the image output characteristics of the printer.

This processing is performed by software processing.

The image data output from the color correction processing unit 105 is stored in the buffer memory under the control of the buffer controller. The reason for this is that the reading process of the scanner is faster than that of the printer, so that it must be matched with the speed of the printer.

Here, the buffer memory 111 is composed of a buffer of at least two lines, and the buffer controller 10
Under the control of 9, the image read by the scanner is stored in one line buffer, and the image data is transferred from the other line buffer to the resolution conversion unit.

The resolution converter 113 enlarges the input image data according to the resolution of the printer. As a result, image data necessary for showing the image of the original size is generated from the image reduced by the reduction processing unit 103.

In the above processing, the reduction processing unit 10
The relationship between 3 and the resolution conversion unit 113 will be briefly described. The image that has been reduced in size by the reduction processing unit 103 (the amount of data has been reduced by thinning out pixel values) is reproduced as an image that is the same size as the input image, taking into consideration matching with the resolution at the time of printer output.

For example, when the input image is A4 size image data of 360 dpi (scanner resolution), the reduction processing unit 103 performs reduction processing as an A5 size image. As a result, the amount of image data can be reduced by half. After performing predetermined image processing thereafter, the resolution converting unit 113 performs enlargement processing and resolution conversion processing on an image of A4 size and 720 dpi (printer resolution). The above processing is specifically performed.

The image converted into the printer resolution by the resolution conversion unit 113 is binarized by the binarization processing unit 115 using the error diffusion method. The above processing is an example when the printer uses an inkjet printer that can output only binary images, and is output as it is in the case of a thermal sublimation printer or the like capable of expressing multivalued images.

The image processed by the binarization processing unit 115 is
It is output from the printer 119 on a recording medium. This completes the image copying process.

Next, the operation in the monochrome mode will be described. The image data read by the scanner 121 is stored in the buffer memory 125 using the buffer controller 123. The reason for storing is the same as that for the color mode, but since the image data is monochrome data, the amount of the buffer memory needs only to store only the monochrome component obtained from RGB in the memory. Therefore, when the memory is shared between the color mode and the monochrome mode, the monochrome mode can operate at a higher resolution.

Note that the upper and lower block diagrams of FIG. 1 are described separately, but as described above, blocks having similar functions (the scanner 101 and the scanner 121, etc.) may be commonly used. Makes the block structure simple.

The image data stored in the buffer memory 125 is subjected to resolution conversion in accordance with the printer resolution as in the color mode. If the printer 129 is a binary printer, it is binarized and output to the printer. . Since the character image is basically output in the binarization process at this time in the monochrome mode, the pseudo halftone process such as error diffusion is not necessary and the binarization using the fixed threshold value (simple binarization) is performed. Further, when halftone processing is required, a mode for executing pseudo halftone processing may be prepared, and simple binarization processing and pseudo halftone processing may be switched and used.

In the embodiment described above, image processing such as color conversion can be efficiently performed in the color mode. Further, it is possible to reduce the buffer memory.

Further, although the resolution of reading is deteriorated by the reduction processing of the reduction processing unit 103 of the present embodiment, a color image is intended for processing an image such as a photograph, and even if the resolution is lowered, the image resolution is sufficiently reduced. Since it can be reproduced, even if the reduction processing as in the present embodiment is performed, the visual quality of the image is not deteriorated. Further, in the monochrome mode, image processing is simple, and since the amount of image data is small, it is not necessary to reduce the resolution in the reduction processing unit 103, and a character image can be copied by fully utilizing the resolution of the scanner.
An image with good image quality can be obtained.

Further, in the present embodiment, when the resolution conversion processing is performed in accordance with the printer resolution, it is possible to control so that it is always an integral multiple. As a result, the resolution conversion process can be simplified, and the speed of the entire copying process can be increased.

FIG. 2 shows the buffer control unit 109 or 123.
This is an example of the configuration. 201 is a read data register for temporarily storing data for reading image data, 2
Reference numeral 03 is a read address counter for generating a read address, 205 is a write data register for temporarily storing data for writing image data, and 207 is a write address counter for generating a write address.

Reference numerals 209 and 211 denote an address bus and a data bus of the line buffer memory, and 213 is a line buffer for storing image data.

The operation of the buffer control unit 109 or 123 is the same as the control operation of a normal double buffer, so the description of the operation will be omitted. The scanner speed can be adjusted to the printer speed by stopping the scanner at the time of storage.

With such a configuration, it is possible to read and write the image data in a time division manner, but it is necessary to make the read / write of the memory sufficiently faster than the reading speed of the image data accordingly. Therefore, in the color mode, it is advantageous from the point of view of buffer control and memory access to perform the reduction process after reading as shown in FIG.

If the memory 107 and the work memory 117 shown in FIG. 2 have the same structure as that of the line buffer 213, the cost can be reduced and it is advantageous in terms of memory access.

FIG. 3 shows the internal structure of the color correction processing section. This part performs a process of converting image data represented by RGB read by a scanner into CMYK image data suitable for the printer.

First, the RGB image data is converted into CMY data by converting the brightness density in the brightness density conversion unit 301. After that, the black extraction unit 303 generates K to obtain CMYK data. The CMYK data is masked by the masking processing unit 3
The CMYK data corrected to the printer color is generated by executing the 4 × 4 matrix operation in 05, and finally the gamma correction unit 307 performs the gamma correction process for correcting the density curve of the printer, and the read image data RGB is obtained. It is corrected to CMYK image data that matches the printer.

FIG. 4 is a diagram in which the calculation executed by the color correction unit 105 is represented by an equation. The brightness density conversion unit 301 is R
The LOG operation is independently executed for the GB component and converted into CMYK (in practice, the log operation is often performed in a table).

The black extraction unit 303 is composed of a minimum value circuit for calculating minimum value data from CMYK data.

The masking processing unit 305 executes a 4 × 4 matrix operation on CMYK to generate CMYK data (C1, M1, Y1, K1) that matches the output characteristics of the printer.

The gamma correction unit 307 performs density conversion by referring to a CMYK independent lookup table.

Although this embodiment has been described as an apparatus using a block diagram, it may be performed using software on a computer. In that case, the scanner 101, 1
A computer may be connected to the printer 21 and the printers 119 and 131 and the above-mentioned image processing may be performed inside the computer.

As described above, in the image processing apparatus according to the present embodiment, the image data read from the scanner is subjected to the processing of temporarily lowering the resolution, thereby performing the image processing of the image data having the reduced data amount. By increasing the resolution of image data, it is possible to reduce the speed of image processing, the memory used for image processing, and the like.

[0049]

As described above, according to the present invention,
It is possible to reduce the load of image processing of image data having a large data amount and to perform image processing efficiently.

Specifically, it is possible to reduce the image processing load of color image data and efficiently perform image processing.

Furthermore, it is possible to reduce the capacity of the memory used for image processing of image data having a large amount of data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a color copying apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of a buffer control unit and a buffer memory shown in an overall configuration.

FIG. 3 is a diagram showing an internal configuration of a color correction unit shown as an overall configuration.

FIG. 4 is a diagram illustrating a calculation executed by a color correction unit.

[Explanation of symbols]

101 Scanner for Reading Image 103 Reduction Processing Unit for Thinning Out Image Data 105 Color Correction Processing Unit for Matching Input Color from Scanner to Output Color of Printer 107 Memory that Stores Parameters for Performing Color Correction 109 Scanner and Printer Processing Speed A buffer controller for adjusting the difference between the scanner and the printer 111 A buffer for adjusting the difference in the processing speed between the scanner and the printer 113 A resolution converter 115 for converting the resolution for the printer 115 Binary Binary processing for binarization Digitization processing unit 117 work memory for performing binarization processing 119 printer for outputting an image 121 scanner for reading an image 123 buffer controller for adjusting a difference in processing speed between the scanner and the printer 125 Buffer for adjusting differences 1 7 Resolution conversion unit for converting to printer resolution 129 Binary processing unit for performing binarization processing according to binary printer 131 Printer for outputting image 201 Register for temporarily storing read data 203 Address for read data Generated address counter 205 Register for temporarily storing write data 207 Address counter for generating write data address 209 Line buffer memory address bus 211 Line buffer memory data bus 213 Line buffer memory 301 RGB in color correction unit ~ Luminance density conversion unit for CMY conversion 303 Black extraction unit for extracting black component from CMY in color correction unit 305 Masking calculation unit for matching color to printer in color correction unit 307 Color correction unit for printer in color correction unit Convert the density curve Gamma converter

Claims (8)

[Claims] 1. An image processing apparatus for copying an image, comprising: a reading unit that reads the image and generates image data; and a first resolution conversion unit that performs resolution conversion to reduce the resolution of the image indicated by the image data. Image processing means for performing predetermined image processing on the image data whose resolution has been converted by the first resolution converting means, and resolution conversion for increasing the resolution of the image indicated by the image data processed by the image processing means. An image processing apparatus comprising: a second resolution conversion unit; and an output unit that visually outputs the image data whose resolution has been converted by the second resolution conversion unit. 2. The image processing apparatus according to claim 1, wherein the image data is color image data. 3. The image processing apparatus according to claim 1, wherein the resolution conversion by the second resolution conversion means is performed so as to match the resolution of the printer. 4. The image processing apparatus according to claim 1, wherein the image processing means includes a buffering means for buffering image data. 5. The image processing apparatus according to claim 3, wherein the resolution conversion by the second resolution conversion means is controlled so as to be an integral multiple conversion. 6. The image processing apparatus according to claim 1, wherein the image processing by the image processing means is realized by software. 7. The image processing apparatus according to claim 1, wherein the image processing apparatus has a color copying mode and a monochrome copying mode, and the first resolution converting means is not performed in the monochrome copying mode. apparatus. 8. An image processing method for copying an image, the reading step of reading the image to generate image data, and a first resolution conversion step of performing resolution conversion for reducing the resolution of the image indicated by the image data. An image processing step of performing predetermined image processing on the image data whose resolution has been converted in the first resolution conversion step, and a resolution conversion for increasing the resolution of the image indicated by the image data processed in the image processing step. An image processing method comprising: a second resolution conversion step; and an output step of visually outputting the image data whose resolution has been converted in the second resolution conversion step.