JP2002281301A - Image processor, image processing method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor capable of reproducing an image by enhancing legibility of characters on dots and color grounds when reproducing the image data by attaching importance to the characters. SOLUTION: The image processor generates image data for reproduction by performing a prescribed processing to the image data. In this case, when an image is reproduced by performing γ conversion to original image data, the image is reproduced by more linearly controlling γ characteristics in a character edge area existing on a dotted ground or the color ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, an image processing method, and a recording medium for improving image quality of an output image with respect to digital image processing, and more particularly, to a facsimile, a digital copying machine, and a network of digital image data obtained through a network. This is suitable for application to image processing of a character string on a point area or a color background area.

2. Description of the Related Art Conventionally, a facsimile machine has a process for a character mode in which a text document is emphasized and transmitted. In particular, some inexpensive facsimile machines have only processing corresponding to this mode. This character mode processing is a γ conversion process called high γ (see FIG. 9) for performing high γ conversion on the density of an input pixel to obtain the density of an output pixel for character image quality or transmission efficiency. A typical example is to perform binarization with a predetermined threshold value. By performing such γ conversion, the image quality of a character having a white background (including a low-contrast character) is improved, and the white pixel area and the black pixel area are present to some extent in a lump, so that the transmission efficiency is also improved. Will rise.

[0002]

Documents that may be sent in the character mode include characters with halftone dots in the background (hereinafter referred to as halftone characters) and black characters with solid colors in the background. (Hereinafter referred to as "color ground characters") There are originals and the like, but when such originals are transmitted and reproduced by the high γ conversion processing, for example, it is often observed that, for example, catalogs or the like cannot be read as characters at all. For example, referring to FIG. 10, when a high-γ conversion process is performed on a document of a character string having a halftone dot background on the left side of FIG. 10, a result shown on the right side of FIG. 10 is obtained. A character string "aiueo" is buried in a halftone dot and cannot be read at all. Conversely, if a halftone text original or color ground text original is processed and reproduced by performing binarization using the error diffusion method often used for halftone processing in the picture mode, Although the readability of the data is improved, the data amount is dramatically increased, and the transmission efficiency is reduced in a device for transmitting data such as a facsimile device. If the transmission efficiency is deteriorated, the transmission time becomes longer, which imposes an economic burden on the user. The present invention has been made to solve the above-described problem, and when performing character-oriented image reproduction on image data, it is possible to improve the legibility of characters on a halftone dot area or a color ground area and to improve the data amount. It is an object of the present invention to provide an image processing apparatus, an image processing method, and a recording medium that reproduce images without increasing the number of images, and that are inexpensive and have a reduced hardware scale.

[0003]

According to a first aspect of the present invention, there is provided an image processing apparatus for performing a predetermined process on image data to generate reproduction image data. The predetermined processing is such that, when performing gamma conversion on the original image data and reproducing the image, the gamma conversion is performed on a character edge area existing on a halftone dot or a color ground of the original image data. The gamma characteristic is controlled more linearly. An image processing apparatus according to a second aspect of the present invention is an image processing apparatus that performs predetermined processing on image data to generate image data for reproduction, and exists on a halftone dot or on a color ground of the image data. The image processing apparatus further includes a character edge area detecting unit that detects a character edge area, wherein the predetermined process performs γ conversion on the original image data and reproduces the image. The gamma characteristic of the detected character edge area is controlled more linearly. An image processing apparatus according to a third aspect of the present invention is an image processing apparatus that performs predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed on intermediate image data with respect to original image data. A halftone process that reproduces an image by performing tone processing, and makes the character edge area existing on halftone dots or color ground of the original image data a halftone that has higher gradation preservation than other areas. Processing is performed. An image processing apparatus according to a fourth aspect of the present invention is an image processing apparatus that performs predetermined processing on image data to generate image data for reproduction, and exists on a halftone dot or on a color ground of the image data. A character edge area detecting means for detecting a character edge area, wherein the predetermined processing is to perform halftone processing on the original image data to reproduce an image, and the predetermined processing is performed by the character edge area detecting means. It is characterized in that halftone processing is performed in which the character edge area becomes a halftone with higher tone preservation than other areas.

According to a fifth aspect of the present invention, there is provided an image processing apparatus for performing a predetermined process on image data to generate image data for reproduction, wherein the predetermined process includes:
When performing gamma conversion on the original image data, the gamma characteristic of the character edge area existing on the halftone dots or the color ground of the original image data is more linearly controlled, and the gamma conversion is performed on the halftone dots or the color of the original image data. An image is reproduced by performing a halftone process in which a character edge region existing on the ground becomes a halftone with higher gradation preservation than other regions. An image processing apparatus according to a sixth aspect of the present invention is an image processing apparatus that performs a predetermined process on image data to generate image data for reproduction, wherein the predetermined process performs γ processing on the original image data. When performing the conversion, the gamma characteristic of the character edge area existing on the halftone dot or on the color ground of the original image data is converted to be more linear in accordance with the characteristic of the subsequent halftone processing, and the original image data is converted. An image is reproduced by performing a halftone process that makes a character edge region existing on a halftone dot or on a color ground a halftone having higher gradation preservation than other regions. According to a seventh aspect of the present invention, in the image processing apparatus according to any one of the third to sixth aspects, the halftone processing is performed by an error diffusion method or an average density storage method. It is characterized by being. Further, the image processing method of claim 8 of the present invention
An image processing method for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing includes performing γ conversion on original image data and reproducing the image. Is characterized by more linearly controlling the γ characteristic of a character edge area existing on a halftone dot or a color ground of the original image data.

According to a ninth aspect of the present invention, there is provided an image processing method for performing predetermined processing on image data to generate image data for reproduction.
An image is reproduced by performing halftone processing on the original image data by the error diffusion method or the average density storage method,
It is characterized in that a halftone process is performed in which a character edge region existing on a halftone dot or a color ground of the original image data has a higher halftone preservation than other regions.
An image processing method according to a tenth aspect of the present invention is an image processing method for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed on the original image data by γ When performing the conversion, the gamma characteristic of the character edge area existing on the halftone dot or on the color ground of the original image data is converted to be more linear in accordance with the characteristic of the subsequent halftone processing, and the original image data is converted. An image is reproduced by performing a halftone process that makes a character edge region existing on a halftone dot or on a color ground a halftone having higher gradation preservation than other regions. Further, claim 1 of the present invention
The first recording medium is a computer-readable recording medium that records a program for causing a computer to function as an image processing apparatus that performs predetermined processing on image data to generate image reproduction data, When performing gamma conversion on the original image data, the gamma characteristic of the character edge region existing on the halftone dots or on the color ground of the original image data is made more linear in accordance with the characteristics of the subsequent halftone processing. The image is reproduced by performing halftone processing that makes the character edge area existing on the halftone dots or color ground of the original image data more halftone-preserving than the other areas. The image processing program for realizing the function of recording is recorded.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention. An image input device 1 for inputting an image signal by a scanner or the like using a CCD device or the like, a character edge region or a color background A halftone / color ground character edge detection circuit 2 for detecting a character edge area on the area; a first processing circuit 3 for an edge area detected by the halftone / color ground character edge detection circuit 2; A second processing circuit 4 for a non-edge area detected by the halftone / color ground character edge detection circuit 2, based on an area identification signal from the halftone / color ground character edge detection circuit 2. The selection circuit 5 selects and outputs one of the output signals from the first processing circuit 3 or the second processing circuit 4. Based on the output image signal of the selection circuit 5, an image is output by an image output device such as a facsimile device, a digital copying machine or a printer (not shown), or is output from an image output device connected via a network. You. The image signal input from the image input device 1 is data obtained from, for example, a scanner using a CCD element or the like. After reading an original image at a resolution of 600 dpi and performing A / D conversion processing, 8 bits are output to each pixel. Output an image signal which is substantially linear in density. Here, for the sake of explanation, it is assumed that “0” represents white of the document and “255” represents black of the document as signal meanings. Further, the input image signal may be image data obtained through a network. The input image data that has been input is, for example,
It is supplied to the color ground character edge detection circuit 2, the first processing circuit 3 and the second processing circuit 4. The halftone / color ground character edge detection circuit 2 detects a character edge area (for example, a halftone area as shown in the lower part of the figure on the left side of FIG. 10) on a halftone area or a color background area of the input image data. Upper character edge)
Is detected.

FIG. 2 shows a detailed configuration of the halftone / color ground character edge detection circuit 2. 2, an edge detection circuit 21, a color background region detection circuit 22 for detecting a halftone dot region or a color background region portion, an output signal of the edge detection circuit 21, and an output signal of the color background region detection circuit 22 And an AND circuit 23 for calculating a logical product of the two. AND
When the output signal of the circuit 23 is a true value, this area indicates a character edge on the halftone dot area portion or the color ground area portion. The edge detection circuit 21 performs a Laplacian filter as shown in FIG. 3 for calculating the likelihood of an edge from local information in the vicinity of the target pixel, and sets a target pixel whose calculated value is equal to or larger than a predetermined threshold value as an edge. Activate the flag for the pixel of interest. Flags for other pixels are made non-active. This operation is performed for one line of pixels, and stored in the memory as character edge information.

FIG. 4 shows a detailed configuration of the color background area detection circuit 22. The color background area detection circuit 22 is configured to detect a white background area using a known technique (for example, a technique disclosed in Japanese Patent Laid-Open No. 14378/1992) and detect an area other than the white background area as a color background area. can do. First, the white lump detection circuit 221 applies a 7 × 7 pixel mask to the target pixel of the target image,
When all the pixels in the mask 7 are equal to or smaller than a predetermined threshold (that is, a cluster of white pixels), the flag for the target pixel at the center is activated, and the other pixels are deactivated. This operation is performed on pixels of six lines in the target image, and stored in the memory as white lump information. The blocking circuit 222 divides the white lump information detected by the white lump detection circuit 221 into blocks of, for example, 6 × 6 pixels. If at least one active pixel is included in this block, the block is activated. This operation is performed on at least 2 × 16 + 1 blocks and stored in the memory as block information. The correction circuit 223 looks at the periphery of the block of interest based on the block information detected by the blocking circuit 222, so that the block of interest is surrounded by a white background (such an area is defined as a white background area). Is determined, and a correction process is performed.
For example, in order to determine whether or not the block of interest is a white background area, as shown in FIG. That is, if any one block information of the 16 blocks in the left area (A area) is active, the A area is made active. Similarly, the other three areas (B, C, and D areas) are processed in the same manner. If all four of these areas (A, B, C, D) are active,
The block of interest (G) is determined as a white background area,
If there is inactive block information in any of the four areas (A, B, C, D), it is determined that the target block (G) is not a white background area, and the block information is corrected to non-active. This operation is performed on all blocks having active block information. The inversion circuit 224 inverts the active and non-active flags for the block information obtained by the correction circuit 223. As a result, the block having the active block information is determined and detected as belonging to the color background area.
If the block information corresponding to the pixel of the character edge information calculated by the edge detection circuit 21 is active, the AND circuit 23 finally converts the pixel in this line to the character edge in the halftone dot area or the color ground area. And outputs an active signal, and outputs a non-active signal to the other pixels. This result is stored in the memory as halftone / color ground character edge information for each line.

FIG. 6 is a block diagram showing a detailed configuration of the first processing circuit 3 of FIG. In order to improve the legibility of a character string on a halftone dot area or a color background area, it is necessary to maintain the gradation of the original image as much as possible. Therefore, the first processing circuit 3 outputs the first image data 1
Processing is performed on the assumption that a character string exists on a halftone dot area or a color ground area based on the line information. The first γ conversion circuit 31 has a linear relationship between the input density of the original image and the output density of the reproduced image (dotted line in FIG. 7) in consideration of the characteristics of the pseudo halftone processing at the subsequent stage.
Is performed so as to be close to That is, for each input density, a γ characteristic is measured in advance for the halftone processing method executed by the pseudo halftone circuit 32, and an inverse conversion value is calculated so that the γ characteristic becomes linear, The density and the inverse conversion value are stored in a table. Next, the first γ conversion circuit 31 is operated for the image data, an inverse conversion value is calculated by applying the previous table to the input density of the image data, and a pseudo half tone is calculated for the inverse conversion value. By applying the circuit 32, the relationship between the input density for the image and the output density for the reproduced image is substantially linear. It is also possible to perform gamma conversion processing (solid line in FIG. 7) to make the character more readable by, for example, whitening the outline of the character. Next, the pseudo halftone circuit 32 selects a pseudo halftone process which is excellent in both resolution and gradation so as to preserve the density of the original image, for the output signal processed by the first γ conversion circuit, Perform halftone processing. In this halftone processing method, generally, a spiral type dither process is performed to perform binarization. However, another binarization process may be used as long as the above condition is satisfied. For example, the error diffusion method (for example, the literature R. Floyd L. Steinberg, "An Adaptive Algorithm
m for Spatial Gray Scale ", SID 75 Digest, pp 36-3
7) or any method such as the average density preservation method (for example, "Developing a 800,000-color copier capable of expressing 16.7 million colors" Nikkei Electronics 1992.5.25 (No.555) pp203-214) By doing so, legibility can be improved. The result of the pseudo halftone circuit 32 is the output of the first processing circuit 3.

FIG. 8 is a block diagram showing a detailed configuration of the second processing circuit 4 of FIG. It is necessary to perform processing that emphasizes conventionally used characters in areas other than the areas detected as character edges on the halftone dot area or the color ground area. Therefore, the second processing circuit 4 performs processing on such an area. The second γ conversion circuit 41 performs a primary conversion process on the density of the input image so as to obtain an output density having a relationship as shown by a solid line in FIG. Edge emphasis circuit 42
With respect to the output signal from the second γ conversion circuit 41,
At the time of determining the threshold value of the black pixel and the white pixel, the image is emphasized by performing a filtering process using an edge emphasizing differential filter in order to obtain an effect that the pixel is not fluctuated due to a situation change at the time of image input. The binarization circuit 43 binarizes the output signal from the edge enhancement circuit 42 by comparing the output signal with a predetermined threshold. The binarized result is sent to a second processing circuit 4
Output. Finally, the selection circuit 5 (see FIG. 1) applies the output signals from the above three circuits (halftone / color ground character edge detection circuit 2, first processing circuit, and second processing circuit). The following selection is made for each pixel. When the halftone / color ground character edge information is active in response to the output signal (region identification signal) from the halftone / color ground character edge detection circuit 2, the output signal from the first processing circuit is output. select. -When inactive, select an output signal from the second processing circuit. By configuring the image processing apparatus of the present embodiment in this way,
Conventionally, for example, in the character mode of a facsimile machine, characters on a halftone dot area or a color background area have been buried in the background and have become invisible.However, only the character edge area of this part is faithful to the original image. Since such γ conversion processing is performed, the readability is improved because the input / output linearity is improved, and the entire data amount is not increased, so that the transmission efficiency in a facsimile apparatus or the like does not need to be reduced so much. In addition, only for the character edge area on the halftone dot area or the color background area, the mode is switched to the pseudo halftone processing that preserves the tone characteristics faithful to the original image. Since the readability is improved and the total data amount does not increase, the transmission efficiency in a facsimile apparatus or the like does not need to be reduced so much.

Next, the operation of the image processing apparatus of the embodiment configured as described above will be described. The image data is read from the image input device 1 through a scanner or a network using a CCD device or the like. After the A / D conversion process, the read image data outputs an 8-bit, substantially linear image signal for each pixel. For example, halftone / color ground character edge detection is performed sequentially for each line. The circuit 2, the first processing circuit and the second processing circuit are supplied in parallel. First, the halftone / color ground character edge detection circuit 2 detects a character edge area on a halftone area or a color ground area of the input image signal. When the edge detection circuit 21 detects a character edge and the color background area detection circuit 22 detects a halftone area or a color ground area, this area is set to a halftone / color ground character edge. Output signal. For this purpose, the edge detection circuit 21 receives information on the number of lines required for calculating the Laplacian filter from the image memory, and performs filtering for each pixel of interest. A pixel of interest whose calculated value is equal to or greater than a predetermined threshold value is defined as an edge, and a corresponding buffer memory is activated. With this operation, calculation for one line is performed. At the same time as the operation of the edge detection circuit 21, the color background area detection circuit 22 operates so as to detect a white background area and detect an area that is not a white background as a color background area. First,
The white block detection circuit 221 receives, for example, image data for seven lines. Apply a 7x7 pixel mask to this,
When all the pixels in the 7 × 7 mask are equal to or smaller than a predetermined threshold (that is, a cluster of white pixels), the central target pixel is activated. This operation is performed on the pixels for six lines, and the flag information is stored in the buffer memory.
Next, the blocking circuit 222 divides the flag information for six lines detected by the white block detection circuit 221 into, for example, a block of 6 × 6 pixels, and includes at least one active pixel in this block. Activate that block. This operation is performed for (2 × 16 + 1) blocks, and stored in the buffer memory as block information. Based on the (2 × 16 + 1) pieces of block information detected by the blocking circuit 222, the correction circuit 223 determines whether at least one of the upper, lower, left, and right blocks of the target block is inactive. It is determined that the target block is not a white background area, and the block information is corrected to non-active. The inversion circuit 224 inverts the active and non-active flags for the block information obtained by the correction circuit 223. As a result, the block having the active block information is determined and detected as belonging to the color background area.

The first processing circuit 3 (comprising the first γ conversion circuit 31 and the pseudo halftone circuit 32) operates in parallel with the operation of the halftone / color ground character edge detection circuit 2. . First, the first γ-conversion circuit 31 performs a primary conversion process such that the output density of the reproduced image becomes nearly linear with respect to the input density of the original image data, in consideration of the characteristics of the pseudo halftone processing at the subsequent stage. Also, a gamma conversion process is performed to make the character more readable by, for example, whitening the outline of the character. next,
For the output signal processed by the first γ conversion circuit, the pseudo halftone circuit 32 performs a spiral type dither process to binarize the signal, or calculates the density of the original image by an error diffusion method, an average density storage method, or the like. A pseudo halftone processing method that is excellent in both resolution and gradation to be stored is selected and executed, and the result of the halftone processing is used as an output signal of the first processing circuit 3. Also,
The second processing circuit 4 (consisting of a second γ conversion circuit 41, an edge enhancement circuit 42, and a binarization circuit 43) is also
It operates in parallel with the operation of the color ground character edge detection circuit 2,
Performs processing that emphasizes conventionally used characters. First, the second γ conversion circuit 41 performs a primary conversion process on the density of the input image data stored in the image memory so as to obtain an output density having a relationship as shown by a solid line in FIG. next,
The edge enhancement circuit 42 performs a filtering process on the output signal from the second γ conversion circuit 41 with an edge enhancement differential filter to enhance the image. The binarization circuit 43 binarizes the output signal from the edge emphasis circuit 42 by comparing it with a predetermined threshold value. The binarized result is used as the output of the second processing circuit 4. Finally, the selection circuit 5 performs the following judgment for each pixel based on the output signal from the halftone / color ground character edge detection circuit 2 and outputs the selected output signal. An output signal from the first processing circuit 3 for a pixel which is a character edge on a halftone dot area or a color ground area; The second processing circuit 4 for pixels in other areas
Output signal from.

<Modification of Embodiment> In the above-described embodiment, three circuits (halftone / color ground character edge detection circuit 2, first processing circuit 3, and second processing circuit 4) are used in parallel. And finally the first processing circuit 3
And the output of the second processing circuit 4 have been selected,
The halftone / color ground character edge detection circuit 2 is operated, and when the detection result is a halftone / color ground character edge, the first processing circuit 3 is operated. The same result can be obtained by configuring the selection circuit 5 so as to select the second processing circuit 4.

<Example by Computer> Further, the present invention is not limited to only the above-described embodiment.
The respective functions constituting the image processing apparatus for realizing the functions of the above-described embodiment are programmed respectively, and a CD-RO
M, etc., and the CD-ROM is mounted on a computer equipped with a medium drive device such as a CD-ROM drive, and these programs are stored in the memory or storage device of each computer.
By doing so, the object of the present invention can be achieved. As a recording medium, a semiconductor medium (for example, ROM, IC memory card, etc.), an optical medium (for example,
DVD, MO, MD, CD-R, etc.) and magnetic media (for example, magnetic tape, flexible disk, etc.). When the program for realizing the above-described embodiment is a semiconductor recording medium such as a ROM or the like, the program is directly loaded into the memory and executed, not from the medium driving device. Further, not only the functions of the above-described embodiments are realized by executing the loaded program, but also the operating system or the like performs part or all of the actual processing based on the instructions of the program, and the processing performs The case where the functions of the above-described embodiments are realized is also included. Further, a program for realizing the functions of the above-described embodiment is loaded into the memory provided on the function expansion board or the function expansion unit, and the CPU or the like provided on the function expansion board or the function expansion unit is actually executed based on the instructions of the program. And a part of the entire process is performed, and the function of the above-described embodiment is realized by the process.

<Operation of Network Environment of the Present Invention> The present invention may be configured to operate by connecting to a network. For example, a server computer holding an image processing program and a terminal for inputting an image by a user and outputting the result (including output to a printer, a display, a storage device, and transmission to another terminal) are connected via a network. . This network is a transmission path for coupling a server computer and a user terminal, and is generally realized by a cable, and a communication protocol is TCP / TCP.
IP is used. However, the transmission path is not limited to the cable, but may be any of wireless, wired and broadcast waves as long as the communication protocol between them is the same. For example, a LAN (Local Area Network), WAN (Wide Are)
a Network), Internet, analog telephone network, digital telephone network (ISDN: Integral Service Digital Net)
work), PHS (Personal Handy Phone System), mobile phone network, satellite communication network, and the like. The user terminal receives the image processing program from the server computer, inputs an image, executes the received program, and outputs the execution result. This has the advantage that the program is always up to date. When the server computer and the user's terminal are connected via a network, a program for realizing the functions of the present invention is stored in a storage device such as a magnetic disk of the server computer,
It can also be distributed to terminals in a form such as download. Further, the program for realizing the functions of the present invention may be provided by distributing it by broadcast waves.

[0016]

As described above, the characters in the halftone dot area and the color ground area have been buried in the background in the character mode of a facsimile machine, for example. According to the above, the character edge region of the same portion is detected, and only the region is subjected to the γ-conversion processing so as to be faithful to the original image. Since the data amount is not increased, the transmission efficiency of the facsimile apparatus or the like does not need to be reduced so much. Further, according to the present invention, a character edge region on a halftone dot region or a color background region is detected, and only in that region, pseudo halftone processing of a tone characteristic faithful to the original image is performed. Since the readability is improved by improving the input / output gradation, and the total data amount is not increased, the transmission efficiency does not need to be reduced much in a facsimile apparatus or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a halftone / color ground character edge detection circuit.

FIG. 3 is a diagram illustrating an example of coefficients of a Laplacian filter.

FIG. 4 is a block diagram illustrating a detailed configuration of a color background area detection circuit.

FIG. 5 is a diagram illustrating a correction process.

FIG. 6 is a block diagram illustrating a detailed configuration of a first processing circuit.

FIG. 7 is a diagram illustrating γ characteristics used in a first γ conversion circuit.

FIG. 8 is a block diagram illustrating a detailed configuration of a second processing circuit.

FIG. 9 is a diagram illustrating a γ characteristic used in a second γ conversion circuit.

FIG. 10 is a diagram for explaining a result processed by a conventional image processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image input device 2 Halftone / color ground character edge detection circuit 3 First processing circuit 4 Second processing circuit 5 Selection circuit 21 Edge detection circuit 22 Color background area detection circuit 23 AND circuit 31 First γ conversion circuit 32 Pseudo Halftone circuit 41 Second γ conversion circuit 42 Edge enhancement circuit 43 Binarization circuit 221 White block detection circuit 222 Blocking circuit 223 Correction circuit 224 Inversion circuit

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5B057 CA01 CA02 CA08 CA12 CA16 CB02 CB07 CB12 CB16 CC01 CE03 CE13 CH09 DB02 DB05 DB06 DC16 5C077 LL19 MP02 NN04 NN11 PP15 PP27 PP28

Claims (11)

[Claims] 1. An image processing apparatus that performs predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed when an image is reproduced by performing γ conversion on original image data. An image processing apparatus, wherein the gamma conversion controls the gamma characteristic of a character edge region existing on halftone dots or color ground of the original image data more linearly. 2. An image processing apparatus for performing predetermined processing on image data to generate image data for reproduction, comprising: a character edge area for detecting a character edge area existing on a halftone dot or a color ground of the image data. Detecting means for performing gamma conversion on the original image data and reproducing the image, performing the gamma conversion on the gamma characteristic of the character edge area detected by the character edge area detection means. An image processing apparatus characterized in that the image processing is controlled more linearly. 3. An image processing apparatus for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing reproduces an image by performing halftone processing on original image data. An image characterized by performing a halftone process in which a character edge region existing on a halftone dot or a color ground of the original image data becomes a halftone having higher gradation preservation than other regions. Processing equipment. 4. An image processing apparatus for performing predetermined processing on image data to generate image data for reproduction, comprising: a character edge area for detecting a character edge area existing on a halftone dot or a color ground of the image data. Detecting means for reproducing an image by performing halftone processing on the original image data, and setting the character edge area detected by the character edge area detecting means more than other areas. An image processing apparatus for performing a halftone process for providing a halftone with higher tone preservation. 5. An image processing apparatus for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed when performing γ conversion on original image data.
The gamma characteristic of the character edge area existing on the halftone dot or the color ground of the original image data is controlled more linearly, and the character edge area existing on the halftone dot or the color ground of the original image data is compared with other areas. An image processing apparatus for reproducing an image by performing a halftone process for providing a halftone having higher gradation preservation. 6. An image processing apparatus for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed when performing γ conversion on original image data.
The gamma characteristic of the character edge area existing on the halftone dot or color ground of the original image data is converted to be more linear in accordance with the characteristics of the subsequent halftone processing, and is converted to the halftone dot or color of the original image data. An image processing apparatus for reproducing an image by performing a halftone process on a character edge region existing on the ground so as to provide a halftone with higher gradation preservation than other regions. 7. The image processing apparatus according to claim 3, wherein the halftone processing is processing by an error diffusion method or an average density storage method. apparatus. 8. An image processing method for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing includes performing γ conversion on original image data to reproduce an image. An image processing method for controlling the gamma conversion to more linearly control the gamma characteristic of a character edge region existing on a halftone dot or a color ground of the original image data. 9. An image processing method for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed by using an intermediate method based on an error diffusion method or an average density storage method for original image data. A halftone process that reproduces an image by performing tone processing, and makes the character edge area existing on halftone dots or color ground of the original image data a halftone that has higher gradation preservation than other areas. An image processing method comprising performing processing. 10. An image processing method for performing predetermined processing on image data to generate image data for reproduction, wherein the predetermined processing is performed when performing γ conversion on original image data. The gamma characteristic of the character edge area that exists on the halftone dot of the data or on the color ground is converted to be more linear in accordance with the characteristics of the subsequent halftone processing. An image processing method comprising: performing a halftone process in which a character edge region to be reproduced has a higher halftone preservation than other regions, and reproducing an image. 11. A computer-readable recording medium on which a program for causing a computer to function as an image processing apparatus for performing predetermined processing on image data and generating image reproduction data is recorded, wherein the predetermined processing is performed. When performing γ conversion on original image data, the γ characteristic of a character edge region existing on a halftone dot or a color ground of the original image data becomes more linear in accordance with the characteristic of the subsequent halftone processing. The image is reproduced by performing halftone processing that makes the character edge area existing on the halftone dots or on the color ground of the original image data more halftone preserving than the other areas. A computer-readable recording medium on which an image processing program for realizing a function is recorded.