JP2007036514A - Image conversion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image conversion system capable of reducing the number of gamma tables, and capable of lightening a post-processing. <P>SOLUTION: The image conversion system converts an input image data into an output image data through a gamma conversion processing. The image conversion system has a selection means for selecting the gamma table for a gamma-conversion processing corresponding to the kinds of the specified output image. The input image data are read by a scanner, and the selection means for selecting the gamma table may also be set to a scanner driver. A color-matched image is used as the kind of the output image, and the image conversion system may also have a plurality of the gamma tables so as to correspond to a different image output device. The gamma-conversion processed converted image is pattern-matching processed, and used for specifying an input image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image conversion system for gamma-converting input image data and outputting the image data in various forms.

  In an image conversion system in which an image stored in various recording media or an image read by a scanner is displayed on various displays or printed out, usually input image data is gamma converted (also referred to as gamma correction). ) And output. Image data input / output devices such as scanners and printers have a unique gamma value. To faithfully reproduce an input image, gamma conversion is performed on the image data according to the gamma value of the input / output device. ing. Various proposals have been made regarding optimization and high image quality for images input and output in various forms.

  For example, Japanese Patent Application Laid-Open No. 2004-228561 maintains a gradation for an image that requires gradation, and provides a high-resolution dither for an image that requires a high resolution such as a halftone character or pattern. It is disclosed to perform image processing that can be processed. In this case, a plurality of threshold matrixes having different resolving power and a gamma conversion table for performing a plurality of gamma conversions corresponding thereto are prepared for dither processing. Among these, a specific matrix corresponding to the characteristics required for the image and a corresponding gamma conversion table are selected. For example, a matrix with a higher resolution is selected for an image that requires resolution, and a matrix with a lower resolution is selected for an image that requires gradation reproducibility.

  Further, Patent Document 2 describes that the image quality is deteriorated on the user side by performing correction / conversion processing suitable for various images such as characters and photographs included in a scanned image to be distributed by a copying machine having a distribution function. There has been disclosed image processing that efficiently distributes necessary image data without causing a problem. For example, when delivering color image data input by a scanner or the like, the character portion of the image data to which a character determination signal is attached is corrected using an S-shaped gamma curve to enhance black. To obtain high resolution. In addition, a photographic part to which a photographic determination signal is attached has high gradation by using a linear gamma curve, and it is possible to maintain high image quality of the entire image.

Further, in Patent Document 3, an image that can be easily subjected to pattern matching by gamma conversion to recognize and detect an image that is prohibited from being copied, such as banknotes, from a color image read by a scanner. Processing is disclosed. In this case, if the image to be specified by pattern matching is, for example, an image that is entirely reddish, the ratio of the R component of the RGB image data is high and the GB component is low. Therefore, since the gamma table has one table for each of the RGB colors, it is said that the recognition rate of specific image data can be further improved by using a table that converts in a direction of increasing redness.
JP-A-9-191403 JP 2004-112140 A JP 2001-94774 A

  When an image input by a recording medium or a scanner is to be output by a CRT, LCD, printer, etc., or otherwise to be recognized, the output image is in a state suitable for each output form using gamma conversion processing. Is output. Usually, a plurality of gamma tables for gamma conversion are provided, and the gamma table is automatically referred to according to the input data, and the optimum table is selected.

  However, as disclosed in Patent Document 3 described above, when pattern matching is performed by performing gamma conversion on an input image such as a banknote, pattern matching is executed by the number of gamma tables. When the target of pattern matching is a banknote, if the banknote of each country is included, the burden with respect to pattern matching will also be large and will take time. In addition, there are too many types of images after gamma conversion, and subsequent processing may not be supported. On the other hand, there are cases where the type of image output form is specified in advance. Even in such a case, it is wasteful to prepare a number of gamma tables corresponding to many output forms and select them by referring to them.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image conversion system that can reduce the number of gamma tables and can reduce subsequent processing.

  An image conversion system according to the present invention is an image conversion system that converts input image data to output image data through a gamma conversion process, and selects a gamma table for the gamma conversion process according to the type of the specified output image Selection means is provided. Note that input image data may be read by a scanner, and selection means for selecting a gamma table may be set in the scanner driver. Further, the type of output image may be a color-matched image, and a plurality of gamma tables may be provided so as to correspond to different image output devices. The converted image that has been subjected to the above gamma conversion processing is used, for example, for pattern matching processing to specify an input image.

  According to the present invention, by selecting the output image type (for example, a color matching image) designated by the user, a predetermined gamma table for the output image type is selected. Since the gamma conversion process is performed by the selected gamma table, the gamma conversion process suitable for the type of output image can be performed. Further, since the number of gamma tables can be limited, the subsequent processing can be reduced.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining the outline of the present invention. The image data input unit may be a readable recording medium such as a flash memory, a compact disk, or a flexible disk, or an image is acquired through a network / USB or the like. There is also a case. These image data can be input in various forms by a scanner or the like that is integrally mounted on a personal computer, an image forming apparatus, or the like. The input image includes various forms such as a color image, a monochrome image, a photographic image, and a character image.

  The image data input to the image data input unit is subjected to image processing using information processing means such as a personal computer. In the present invention, the user is provided with selection means for selecting a predetermined output image type. Here, the type of output image is used to mean that the output image is an output image on which processing such as color matching, edge enhancement, contrast strength, noise removal, etc. has been performed. When the user selects the type of output image as described above, a gamma table for executing gamma conversion processing suitable for the type of output image is selected.

  In this case, whether to perform gamma conversion processing or normal gamma conversion processing according to the type of output image is selected. That is, by selecting the type of output image, one of the two gamma tables is selected. The image data that has been subjected to the gamma conversion process using this gamma table can be output after performing another process (Y) or without performing this process.

  After being converted into predetermined image data by gamma conversion processing, it is displayed on a CRT, LCD or the like, or copied and output by a printer. Also, as disclosed in Patent Document 3, it is possible to perform processing that does not output data determined to be copy-prohibited image data. The output image displayed by the display means or copied by the printer can be an image of a type designated by the user prior to image processing, for example, a color-matched image or an edge-enhanced image.

  FIG. 2 is a diagram showing an example in which the present invention is applied to a scanner device. In the figure, 1 is a scanner device, 2 is a scanner driver, 3 is an application, 4 is a document (input image), 5 is a host computer, 11 is an image reading unit, 12 is an image processing unit, 13 is a control means (CPU), Reference numeral 14 denotes a ROM, 15 denotes a RAM, 16 denotes an HDD, 17 denotes a driver IF unit, 18 denotes a display unit, 19 denotes an image data generation unit, 20 denotes a conversion selection unit, 21 denotes a scanner IF unit, 22 denotes an image processing unit, Reference numeral 23 denotes an application IF unit.

  The scanner device 1 includes an image reading unit 11 that reads an image of an original 4 that is an input image and outputs a signal, an image processing unit 12 that processes and outputs the read image data, and a conversion that selects processing in the image processing unit. An image data generation unit 19 including a selection unit 20 is provided. Image data generated by the image processing unit 12 is input to a driver IF (interface) unit 17 to be transferred to the scanner driver 2 and a CPU 13 as control means for controlling the operation and processing of each block.

  In addition, the scanner device 1 provides a ROM 14 storing a control program executed by the CPU 13, a data table referred to by the CPU 13, a work area when the CPU 13 executes the program, and temporarily reads the read image data. RAM 15 for storing and processing the image data, and HDD 16 for storing image data for each page of the document or image data obtained by combining a plurality of pages. The operating state of the scanner device 1 is sequentially displayed by the display means 18.

  The image reading unit 11 has an image sensor 11 a for reading an image of the document 4. The image sensor 11a is configured by, for example, a CCD (Charge Coupled Device) or a CIS (Contact Image Sensor). Further, as an example of the embodiment, the image reading unit 11 includes dedicated image sensors for reading the front surface and the back surface of the document 4, reads the image on the front surface side with the CCD, and reads the image on the back surface side with the CIS. It can also be done. The image reading unit 11 includes an exposure unit that exposes an image of a document, an optical system that guides reflected light to a sensor, and a transport unit that transports the document.

  The image processing unit 12 processes the image data output from the image sensor 11a according to a predetermined procedure. As the processing contents, for example, pattern matching, dither processing, noise processing, and the like can be performed as the above-described gamma conversion processing 12a and processing (Y) 12b. The image data processed by the image processing unit 12 may be temporarily stored in the RAM 15 or the HDD 16 without being compressed or compressed, and may be read later.

  In the present invention, the above-described image data generation unit 19 is particularly provided with a conversion selection unit 20. As described with reference to FIG. 1, the conversion selection unit 20 designates the type of output image, selects a gamma table corresponding to the type, and executes gamma conversion processing 12a for outputting the designated image. . The selection by the conversion selection unit 20 may be in a form in which the user directly inputs from a keyboard or the like. Alternatively, the type of the designated output image may be set in advance in the scanner driver 2 or the like and selected by the driver. The image data converted by the selected predetermined gamma table is further subjected to necessary processing (Y) 12b (for example, pattern matching processing) and output.

  The driver IF unit 17 outputs predetermined image data processed by the image processing unit 12 of the scanner device 1 to the host computer 5 or the like, and functions as an output unit of the scanner device 1. The scanner device 1 and the host computer 5 are communicated via various communication cables by a counter-scanner IF unit 21 provided on the host computer 5 side. The scanner device 1 and the host computer 5 may communicate via a network such as a LAN.

  The hardware of the host computer 5 includes well-known hardware such as a CPU, bus controller, RAM, HDD, communication interface, display, keyboard, and mouse (not shown). In addition, the scanner driver 2 and the application 3 are installed in the host computer 5. The scanner driver 2 is a program indicating a procedure of processing to be executed so that the application 3 can communicate with the scanner device 1 via the application IF unit 23 and control reading of the scanner device 1 to acquire image data. It is. The scanner driver 2 includes a scanner IF unit 21, an image processing unit 22, and an application IF unit 23. The image processing unit 22 in the scanner driver 2 is a processing unit that processes the image data received from the scanner device 1 so as to be passed to the application 3.

  FIG. 3 is a diagram showing a flow for executing the image conversion system of the present invention. First, prior to image conversion processing, the user selects and inputs what type of image is requested as an output image. In the example of FIG. 3, it is assumed that a color-matched image is requested. By specifying a color-matched image as the output image for the input color image, a color image having a color close to the input color image can be printed or displayed on the display or print display. .

  In step S1, “with color matching” is designated as the type of output image, and when the scanning apparatus is ready to be activated, a scan request for an input image is issued from the scanner driver in step S2. Next, in step S3, the color image of the document is scanned, and the image is read by the CCD method or the CIS method. The read image is input to the image processing unit, where gamma conversion processing is performed on the read image. The gamma conversion processing is performed using a preset gamma table, and which gamma table is used is selected according to the type of output image input prior to the start of scanning of the document.

  In the case of this example, since the selection is made depending on the necessity of color matching, if there is color matching in step S4, a gamma table for color matching is selected in step S5. If there is no color matching, a gamma table for no color matching is selected in step S6. Here, when the gamma table for color matching is selected, an image having a color close to the color of the input image can be output as the output image. On the other hand, when a gamma table without color matching is selected, it may be output in a color different from the color of the input image, but the input data from the image sensor can be output as it is, and by gamma conversion Since there is no (or little) data loss, the output image can be easily processed.

  Examples of the image output device medium include a print image, a CRT display image, an LCD display image, and a recording medium. In this way, different output media may require different gamma tables due to different output forms by the output device even with color matching. Therefore, for example, printing, CRT, LCD, etc. may be set as detailed items for color matching, and a gamma table for these may be selected.

  In step S7, gamma conversion processing is executed based on the selected gamma table, and the gamma-converted image data is subjected to other processing as necessary. In this example, pattern matching processing is performed as step S8. This pattern matching can be used when, for example, specifying what kind of input image the image is. Further, when pattern matching is performed with 8 bits and input image data is 10 bits, conversion from 10 bits to 8 bits can also be performed by gamma conversion processing. In this pattern matching, only predetermined image data that has been gamma-converted by the selected gamma table needs to be performed, so that the load is small and the processing speed is high.

  In step S9, the image data subjected to pattern matching and the matching result are transferred to the driver or application. Here, in the driver or application, as disclosed in Patent Document 3, in the case of a banknote in which copying of the input image is prohibited, this is identified by pattern matching. It is possible to prevent the output from being performed or to output in a state where other processing is performed. When the image is not prohibited from being copied, the image data subjected to the gamma conversion process is allowed to be output as a color-matched image.

It is a figure explaining the outline of the present invention. It is a figure explaining the example which applied this invention to the scanner apparatus. It is a figure explaining an example of the implementation flow of the image conversion system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scanner apparatus, 2 ... Scanner driver, 3 ... Application, 4 ... Original (input image), 5 ... Host computer, 11 ... Image reading part, 12 ... Image processing part, 13 ... Control means (CPU), 14 ... ROM 15 ... RAM, 16 is HDD, 17 ... pair driver IF unit, 18 ... display means, 19 ... image data generation unit, 20 ... conversion selection unit, 21 ... scanner IF unit, 22 ... image processing unit, 23 ... pair Application IF part.

Claims (5)

  An image conversion system for converting input image data to output image data through a gamma conversion process, comprising a selection means for selecting a gamma table for the gamma conversion process according to the type of the designated output image. An image conversion system characterized by that.   2. The image conversion system according to claim 1, wherein the input image data is read by a scanner, and the selection means for selecting the gamma table is set in a scanner driver.   The image conversion system according to claim 1, wherein the type of the output image is a color matching image.   4. The image conversion system according to claim 3, wherein a plurality of gamma tables for the color matching image are provided corresponding to different image output devices.   The image conversion system according to claim 1, wherein the converted image that has been subjected to the gamma conversion process is output through a pattern matching process.

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