JP2004112140A - Image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copying machine or the like having a distribution scanner function that applies correction and conversion processing to characters and photos included in a scan image to be distributed adapted to each image type so as to efficiently distribute required data and optimize the utilization of the distribution function without causing deterioration in image quality at a user side. <P>SOLUTION: The copying machine or the like acquires image area separation data (characters, photos, colors and presence / absence of dots) in image processing at scanning, attaches the data to a scanned image and stores the resulting image to an HDD 12. The copying machine or the like sets a processing condition (a gamma correction 141 keeps the high resolution of the character parts and the high gradation of the photos, a color correction 142 uses a parameter proper to each of color characters, black characters, and a dot pattern to convert the image data from the YMCK into the RGB system, and gradation processing binarizes the photos) adapted to each image area by using the image area separation data and applies correction and conversion processing to the image distributed from the HDD to an external PC in response to a distribution request to attain optimization. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus (e.g., a digital color copier connected to a network) having a means (scanner) capable of reading a color original and having a function of delivering the read image data to a use terminal such as a PC. System), if the original image is an image having different image types, such as characters and photographs, divided into one image area, by setting processing conditions suitable for each image area, The present invention relates to the image processing apparatus having means for enabling processing of image data capable of efficiently distributing necessary data without deteriorating image quality.
[0002]
[Prior art]
2. Description of the Related Art In recent years, networking has been advanced in copying machines, and it has become possible to use functions of the copying machine from other terminals connected to the network. For example, a function of distributing image data read by a scanner unit of a copying machine to another user terminal such as a computer connected to a digital color copying machine via a network has been proposed, and is gradually being used.
This function is generally called a distribution scanner function. When using this function, various reading conditions are set from the copying machine side or the computer terminal that is the distribution destination, the scanner is operated in accordance with the set reading conditions, and the read original image data is subjected to predetermined processing, An operation of transferring to a distribution destination is performed.
As a conventional example relating to image reading and image processing performed according to the setting of reading conditions when using the distribution scanner function, the following Patent Document 1 can be shown.
[0003]
[Patent Document 1]
JP 2000-333026 A
Japanese Patent Application Laid-Open No. 2000-333026 discloses that an image forming apparatus such as a copying machine is equipped with an expansion box based on a general-purpose computer system architecture in order to expand functions as a print server or a server for a scanned image. A system has been proposed. Here, it is shown that the scanned image is stored in the hard disk device in the extension box, the stored image file is shared by a computer system connected to a network, and the use thereof can be realized by each server function. .
Patent Document 1 discloses processing of a scanned image when using a scan box function (one of functions for distributing a scanned image to a client computer). Here, it is assumed that scanning of a document and processing of a scanned document image are performed in accordance with the processing conditions set by the operation input. However, since the scan box function is used when print output is not necessarily scheduled, print output is not performed. Without generating the YMCK data format required for scanning, that is, omitting the color conversion and gradation correction from the RGB system to the YMCK system of the scanned image, and storing the processed RGB data in the scan box. are doing. Thereafter, the client computer on the network extracts the image data from the scan box as the RGB data at the time of accumulation, and transfers the image data to a local disk or the like as a storage destination of the client computer. The client computer can browse the scanned image on the monitor / display based on the transferred RGB data.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional delivery scanner function, image data is delivered in an RGB data format that can be used in consideration of the case where the delivery destination is a computer terminal, as seen in Patent Document 1 described above. are doing.
By the way, when the distribution scanner function is used, priority is given to the use on the copying machine side irrespective of the method of omitting the conversion to the YMCK system and accumulating the image in the RGB system as in the scan box function in Patent Document 1 described above. In many cases, a method of first accumulating a scanned image as YMCK-based image data is often employed (also shown in the embodiment of the above-mentioned Patent Document 1 which discloses the print server function).
In the case of using the method of storing with YMCK-based image data, when trying to use the distribution scanner function, in general, a YMCK-based image format is converted to an RGB-based image format to be used in a network. Delivery to.
However, in the method of converting to the RGB system, the conversion to the RGB image format is performed collectively over the entire surface of the CMYK image. In other words, processing such as correction and conversion is performed by applying a certain processing condition to the entire surface without considering the type of image included in the image. Therefore, even if the image is an image having an image portion having different types of images such as characters / photos, colors, and halftone dots, the same format conversion is performed irrespective of the difference. There has been a problem that the image quality when viewing images on the client side may be deteriorated. In addition, since processing conditions suitable for the image type are not used, useless data may be distributed, and a problem may occur that lowers the efficiency of the system.
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems in the related art, and has as its object to have a means (scanner) capable of reading a color original, temporarily store the read image data, and then store the read image data in a computer or the like. In an image processing apparatus having a function of distributing to a user terminal, when distributing an image in which a plurality of image types are included in an image, a correction and / or correction corresponding to each image type included in the image are performed on the scanned image to be distributed. An object of the present invention is to provide the image processing apparatus which can efficiently distribute necessary data without causing deterioration of image quality on the user side by performing a conversion process, and enables optimization of use of a distribution function.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is means for storing image data read from a document in association with image area separation data that separates the document image data by image type, and processing the image data according to a processing condition whose setting is variable. An image processing device for transmitting image data processed by the image processing device via a communication medium, wherein the image processing device transmits the image data stored in the storage device. In doing so, at least one of gamma correction, color conversion, and gradation processing is processing in which processing conditions suitable for each image type are set for image data of each image area indicated by the image area separation data, An image processing apparatus for converting processed image data into a general-purpose format.
[0007]
According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, an image type related to the image area separation data is at least one of various types of characters / photos, colors, and the presence or absence of halftone dots. It is assumed that.
[0008]
According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, the image processing means performs gamma correction adapted to each image area in accordance with image area separation data of characters and photographs. It is a feature.
[0009]
According to a fourth aspect of the present invention, in the image processing apparatus according to any one of the first to third aspects, the image processing means performs each image area according to image area separation data of characters / photos, colors, and the presence or absence of halftone dots. Is characterized by performing color correction conforming to.
[0010]
According to a fifth aspect of the present invention, in the image processing apparatus according to any one of the first to fourth aspects, the image processing means performs gradation processing adapted to each image area according to image area separation data of characters and photographs. Is performed.
[0011]
The invention according to claim 6 is characterized in that a copy function is combined by providing a means for forming a copy image on a recording medium based on the image data stored in the storage means for storing the read original image data. An image processing apparatus according to any one of claims 1 to 5.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An image processing apparatus according to the present invention will be described based on the following embodiments shown with the accompanying drawings. Hereinafter, as an embodiment of the image processing apparatus of the present invention, an example in which the present invention is applied to a digital color copying machine having a function of distributing a read original image will be described.
FIG. 1 is a block diagram schematically showing a system configuration of a digital color copying machine according to the present embodiment.
An image processing system 10 as a digital color copying machine shown in FIG. 1 has a copy function and a distribution scanner function. As elements for realizing the copy function, as shown in FIG. (Scanner / printer) controller 11 and a HDD (hard disk drive) 12 for storing and storing scanned images. The copy unit 13 includes a scanner device 16 that reads a document as color image data, an image processing unit 17 that processes a scanned image into image data in a form used on the user side, and forms a copy image on a recording medium based on the image data. A copy engine unit 15 including a printer device 18 for outputting a copy image; a copy controller 19 for controlling the copy engine unit 15; and an operation panel on which a user sets processing conditions such as a copy mode and inputs a command operation. 20.
Elements for realizing the distribution scanner function include the external I / F image processing unit 14 and the external I / F 10f, and further, a system (scanner / printer) controller 11, HDD 12, and operation panel 20 as elements commonly used for the copy function. Have.
[0013]
Next, the functions of the digital color copying machine constituted by the above-described elements will be described in more detail together with the operation.
First, an operation related to processing when the copy function is used will be described.
The scanner device 16 scans a document by a document scanning unit using a CCD (photoelectric conversion element), thereby forming three colors of R, G, and B (R: RED, G: GREEN, B: BLUE). Generate digital image data for the components.
The RGB image data generated by the scanner device 16 is input to the image processing unit 17. Here, processing such as conversion and correction is performed on the RGB image data into image data used for outputting a copy image by the printer device 18 at the subsequent stage.
FIG. 2 shows the configuration of the processing unit in the image processing unit 17 in more detail.
As illustrated in FIG. 2, the image processing unit 17 performs character / photo determination, color determination, and halftone determination on the RGB image data output from the scanner device 16, and outputs image area separation data indicating the image area. An image area separation unit 171 to generate, a filter unit 172 to smooth and enhance the RGB image data, and C, M, Y, K (C: Cyan, M: Magenta, Y: Yellow, K: The color correction unit 173 includes a color correction unit 173 that converts the image data into four color component image data (Black) and a gradation processing unit 174 that performs gradation processing according to the characteristics of the printer device.
[0014]
When the image to be processed is an image having different image types such as characters / photos, colors, and halftone / non-halftone dots in one image, the image area separation unit 171 determines the image area of each image type. Judge and output as image area separation data. In the present embodiment, as shown in FIG. 3, the inside of the image area separating unit 171 is configured by processing units of a color determining unit 171c, a halftone dot detecting unit 171m, an edge separating unit 171e, and a comprehensive determining unit 171t.
The color determination unit 171c determines whether a pixel of interest is chromatic or achromatic, and can be implemented by applying known means having this function (for example, see Japanese Patent Application Laid-Open No. 2000-125140 (paragraph [ [0126] to [0145], and the description relating to FIGS. 16 to 18).
The halftone dot detection unit 171m determines whether the pixel of interest is a halftone dot or a non-halftone dot, and the edge separation unit 171e determines whether the pixel of interest is an edge or a non-edge. Both dot detection and edge separation can be performed by applying known means having this function (for example, see Japanese Patent Application Laid-Open No. 10-108012 (paragraphs [0011] to [0017], FIGS. 5).
The comprehensive determination unit 171t receives the determination result (1: halftone, 0: non-halftone) of the halftone dot detection unit 171m and the determination result (1: edge, 0: non-edge) of the edge separation unit 171e, and The determination is made as shown in FIG. That is, if edge separation (1) and halftone detection (0), a character area signal is generated, and if edge separation (0), a photographic area signal is generated regardless of the result of halftone detection. Although the above is expressed as a “photograph” area, the entity refers to an area that satisfies the above conditions, and may be referred to as a picture area, but is expressed here as a “photograph” area.
In this manner, the image area separation unit 171 generates a character / photo determination signal, a color determination signal, and a halftone signal as image area separation data.
[0015]
The filter unit 172 uses the character / photo determination signal output from the image area separation unit 171 for the scanned image, and if the pixel of interest is a pixel belonging to the character area, performs an enhancement process on the pixel. For example, a smoothing process is performed, and an RGB signal is output to the next color correction unit 173.
The color correction unit 173 converts the received RGB signals into CMYK signals, and temporarily stores the converted CMYK signals in the HDD 12 by operating the system controller 11. This is to avoid re-reading the original with the scanner even when printing is not completed normally due to a paper jam when printing out a copy using a scanned image, or to perform sort processing. To do it.
When the scan image data is stored in the HDD 12, the CMYK signal output from the color correction unit 173 and the image area separation data (character / photo determination signal, color determination signal , Dot detection signal). The recorded image area separation data is used for an operation when the distribution scanner function described later is used. The scan image data (CMYK signal) stored in the HDD 12 may be subjected to data compression to reduce the data amount.
In the copy operation, the CMYK signal output from the color correction unit 173 may be directly input to the gradation processing unit 174. However, when the CMYK signal output is temporarily stored in the HDD 12 as described above, it is extracted from the HDD 12, and The data is input to the processing unit 174. The gradation processing unit 174 performs gradation processing (γ correction, conversion to a dither pattern, etc.) on the input CMYK signal in accordance with the characteristics of the printer device. The printer device 18 receiving the processed CMYK signal forms a copy image on a recording medium based on the CMYK signal and outputs the copy image.
[0016]
Next, the operation relating to the processing when the distribution scanner function is used will be described, supplementing the means used at the time of distribution.
According to the present invention, a scan image (CMYK signal) is temporarily stored in a storage unit (HDD), and then, when the distribution scanner function is used, a correction / conversion suitable for each image type included in the image is performed on the scanned image to be distributed. By performing the processing, it is possible to efficiently distribute necessary data without deteriorating the image quality at each terminal on the user side such as a PC, a WS, and a server, and to optimize the use of the distribution function. .
For this reason, in the present embodiment, when the scan image data of the CMYK signal stored in the HDD 12 is distributed, the image data is generated by the image area separation unit 171 by the external I / F image processing unit 14 and stored in the HDD 12. The correction / conversion process is performed using the image area separation data (character / photo determination signal, color determination signal, halftone detection signal) recorded together with the data.
The contents of the correction and conversion process
(1) The emphasis is placed on the resolution of the character portion of the image area and the high gradation of the photograph portion.
(2) To improve the image quality of the color character portion.
(3) Improve the image quality of the halftone picture part.
Therefore, a means for this is prepared.
FIG. 5 is a block diagram of the main unit (see FIG. 1) showing in detail the system configuration of a portion related to processing when the distribution scanner function is used.
As shown in FIG. 5, the external I / F image processing unit 14 includes a gamma correction unit 141 that performs gamma correction of CMYK image data, a color correction unit 142 that performs color correction from the CMYK system to the RGB system, An external output processing unit 147 for converting RGB image data into a general-purpose format such as JPEG or BMP format.
[0017]
Next, the flow of image processing up to distribution will be described with reference to FIG.
In the present embodiment, the distribution function is activated by a distribution request command from each terminal such as a PC, a WS, and a server via the external I / F 10f, and a specified file is extracted from the image data stored in the HDD 12, After performing necessary processing on the image data, the image data is distributed to the terminal that has requested the distribution. However, the present invention is not limited to the illustrated embodiment, and may be adapted to perform the procedure starting from the operation of reading the original by the scanner device 16. In addition, a distribution request command issued by an input operation from the operation panel 20 of the apparatus may enable the operation of the distribution scanner function similar to that illustrated, for example.
When distribution processing is instructed for image data in accordance with a distribution request command from an external terminal, the system controller 11 transmits the image data stored in the HDD 12 (for compressed image data, expands and restores the image data). Data) and image area separation data (character / photo determination signal, color determination signal, halftone detection signal), and image processing for external I / F in order to perform image processing of these data as distribution image data. Input to the unit 14.
[0018]
First, when the CMYK image data and the character / photo determination signal as the image area separation data are input to the gamma correction unit 141, the gamma correction unit 141 uses the character / photo determination signal to determine the processing conditions in gamma correction. Switch settings. For example, in an image area of a character portion having a character determination signal, correction is performed using a substantially S-shaped gamma curve as shown in FIG. 6A, and high resolution is obtained by emphasizing black. To do. Further, in the image area of the photographic portion having the photographic determination signal, high gradation is maintained by using a linear gamma curve as shown in FIG. As described above, by switching to the processing condition suitable for each image area of the character portion and the photograph portion, it is possible to maintain high image quality of the entire image.
The gamma-corrected CMYK image data is then input to the color correction unit 142. At this time, a character / photo determination signal, a color determination signal, and a halftone dot detection signal, which are image area separation data, are also input to the color correction unit 142 at the same time.
The color correction unit 142 switches the setting of the color conversion parameter when converting the input CMYK-based image data to the RGB-based image data to be delivered and output, based on the three signals of the image area separation data. For example, as shown in the table of FIG. 7, three types of image data such as a color character, a black character, and a halftone dot pattern are determined from the three types of image area separation data, and the color correction parameters are determined according to the three determination types. Switch.
In other words, the pixels determined to be color characters (edge separation (1), halftone dot detection (0), and color determination (1)) are converted to RGB image data with settings that increase saturation.
For pixels determined to be black characters (edge separation (1), halftone dot detection (0), and color determination (0)), conversion to RGB image data is performed with settings such that the RGB values are equal. For a pixel determined to be a halftone dot pattern (if halftone detection (1), the result of edge separation and color determination is irrelevant), conversion to RGB image data is performed by setting parameters suitable for the halftone dot portion. I do.
As described above, the processing is different between the character portion and the photograph portion, and furthermore, the character portion is converted into RGB image data which makes it easy to distinguish between colored characters and black characters, and the halftone dot pattern portion is also converted with optimal settings. Then, the image data is output to the external output processing unit 147 as image data in a form maintaining high image quality.
[0019]
The external output processing unit 147 further converts the RGB image data input converted by the color correction in the previous stage into image data suitable for the external I / F 10f. To this end, as shown in FIG. 5, the image processing apparatus includes gradation processing units 143 to 145 and an image format conversion unit 146. The format of the image data to be output to the external I / F 10f through the processing of the external output processing unit 147 can be arbitrarily specified on the capturing side such as a PC, WS, or server. For example, a general-purpose image such as TIFF or JPEG is used. It is common to convert to a format. The data converted according to the specified form is delivered to each terminal connected to the external I / F 10f.
Here, the function of the external output processing unit 147 related to the distribution of the scanned image will be described in detail.
In the external output processing unit 147, processing units such as a simple binarization process 143, a binary dither 144, and a multi-value dither 145 are prepared as means for performing a gradation process on the input distribution image data. A character / photo determination signal which is image area separation data is input together with the image data.
One of the gradation processes performed here is, for example, a data format that is convenient when the user wants to perform character recognition on the image data stored in the HDD 12 on the terminal side using an OCR (Optical Character Reader) or the like. This is conversion processing to certain binary data.
Here, the threshold value of the binarization is set low for the image data of the character image area by using the character / photo determination signal associated with the data after the processing by the color correction unit 142. Then, the simple binarization processing unit 143 performs a binarization process. By setting the threshold value for binarization low in the character image area in this manner, the reproducibility of the character portion can be improved even for low-density characters, and the OCR recognition rate can be increased. Also, by handling multi-valued data in a binary manner, the data amount can be reduced, the compression rate of image data is improved, the data amount can be further reduced, and the data transfer time and the memory of the transfer destination memory can be reduced. Reduce usage efficiency. Also, since there is no halftone processing, the size can be reduced as hardware.
Further, when each of the gradation processing units of the binary dither processing 144 and the multi-value dither 145 is used, the data after the processing by the color correction unit 142 is processed by using a character / photo determination signal associated with the data. The dither pattern is changed and the dither processing is performed on the image data of the image area of the image and the image data of the image area of the photograph. That is, by applying the binary dither processing 144 to the character image area of the image data and the multi-value dither 145 to the photographic image area, the resolving power of the character part does not decrease and the gradation of the photographic part is maintained. You.
After performing the above gradation processing, the image is converted into a general-purpose format such as TIFF or JPEG by the image format conversion unit 146, so that it is easy to browse and edit the scanned image at each terminal of the distribution destination. Become.
[0020]
【The invention's effect】
(1) When distributing a document image stored with the effects corresponding to the first and second aspects of the present invention, the image data of each image area indicated by the image area separation data relating to the distribution image is adapted to each image type. By performing at least one of gamma correction, color conversion, and gradation processing by setting the processing conditions to perform, optimal use of the distribution function is achieved without deteriorating the image quality of the image used at the destination. Can be achieved. Further, by setting the image type related to the image area separation data to at least one of various types of characters / photos, colors, and the presence or absence of halftone dots, the invention of claim 1 can be implemented in a more effective form. Become.
(2) Effect of the invention according to claim 3 By performing gamma correction suitable for each image area in accordance with the image area separation data of characters and photographs, high resolution can be achieved in the image area of the character portion. As a result, high gradation can be maintained in the image area of the photographic portion, and high image quality of the entire image can be maintained.
(3) According to the fourth aspect of the invention, color correction adapted to each image area is performed in accordance with the image area separation data of character / photograph, color, and presence / absence of a halftone dot. High image quality can be maintained in each of the portion and the halftone dot pattern portion.
(4) According to the fifth aspect of the invention, tone processing suitable for each image area is performed in accordance with the image area separation data of characters and photographs, so that reproducibility is good in the image area of the character portion. By applying the processing, it is possible to reduce the data amount.In addition, in the image data of the image area of the character and the image data of the image area of the photograph, the dither pattern adapted to each of them is used, and the character portion is It is possible to maintain the gradation of a photographic part without lowering the resolution.
(5) In the image processing apparatus which combines the effect copying function according to the invention of claim 6, by realizing the effects (1) to (4), the performance of the image processing apparatus can be improved. become.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a system configuration of a digital color copying machine according to an embodiment of the present invention.
FIG. 2 shows an internal configuration of an image processing unit in FIG.
FIG. 3 shows an internal configuration of an image area separation unit in FIG. 2;
FIG. 4 shows an image area determination rule of an image type (character / picture) in an image area separation unit.
FIG. 5 is a block diagram of the present apparatus (see FIG. 1) showing in detail a system configuration of a part related to a process when using a delivery scanner function.
FIG. 6 shows correction values used in the gamma correction processing unit of FIG.
FIG. 7 illustrates an image area determination rule of an image type used for color correction of an external I / F image processing unit.
[Explanation of symbols]
10 image processing system 11 scanner / printer controller
12 ... HDD, 13 ... Copying part,
14 image processing unit for external I / F, 15 copy engine unit
16: scanner device, 17: image processing unit,
18 printer device 19 copy controller
20: operation panel, 10f: external I / F,
141: gamma correction unit, 142: color correction unit,
143: a simple binarization processing unit; 144: a binary dither processing unit;
145: Multi-value dither processing unit 146: Image format conversion unit
171: Image processing unit 172: Filter processing unit
173: color correction unit; 174: gradation processing unit.

Claims (6)

Means for storing image data read from a document and image area separation data for separating the document image data by image type in association with each other; an image processing means for processing the image data in accordance with a variable processing condition; An image processing apparatus having a transmission unit that transmits image data processed by an image processing unit via a communication medium, wherein the image processing unit transmits gamma correction when transmitting the image data stored in the storage unit. At least one of the color conversion and the gradation processing is processing in which processing conditions suitable for each image type are set for the image data of each image area indicated by the image area separation data, and the processed image data is generally used. An image processing device for converting the image into a format. 2. The image processing apparatus according to claim 1, wherein an image type related to the image area separation data is at least one of characters / photos, colors, and presence / absence of halftone dots. 3. The image processing apparatus according to claim 1, wherein said image processing means performs gamma correction suitable for each image area according to image area separation data of characters and photographs. 4. The image processing apparatus according to claim 1, wherein the image processing unit performs color correction suitable for each image area according to image area separation data of characters / photos, colors, and the presence or absence of halftone dots. An image processing apparatus comprising: 5. The image processing apparatus according to claim 1, wherein said image processing means performs gradation processing suitable for each image area according to image area separation data of characters and photographs. Image processing device. 6. A copy function is provided by providing means for forming a copy image on a recording medium based on image data stored in the storage means for storing read document image data. An image processing device according to any one of the above.

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