JP2006245808A - Image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of supporting both a standard color space and a color space in response to the characteristic of a printer unit and building up image processing for supporting a spatial frequency characteristic with respect to standard data and a spatial frequency characteristic in response to the printer characteristic, thereby effectively utilizing stored image data. <P>SOLUTION: The image processing apparatus includes: a scanner correction means for applying correction to an image signal resulting from reading an original in matching with the characteristic of prescribed standard data; a storage means for storing the corrected image data; and a printer output means for forming an image on the basis of the image signal resulting from applying correction in matching with the characteristic of a printer output device to the image data stored in the storage means onto paper or the like, and the scanner correction means includes a first filter means for applying correction in matching with the MTF characteristic adaptive to the characteristic of the standard data to the image data, and a printer correction means includes a second filter processing means for applying correction in matching with the MTF characteristic adaptive to the characteristic of the printer output device to the image data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus having a function of distributing and capturing stored images.

Recent copiers are equipped with a scanner function, printer function, facsimile function, etc. in addition to a copy function to control multi-functions and store their output data in an HDD in this device. (See Patent Document 1).
In addition, they can transmit and receive image data stored in the HDD via a network or the like.

  Here, when the image data stored in the storage device is a copy image, there are various types of originals. For example, an original to be copied from an operation unit or the like installed in a device in a copying machine. Is selected, and in response to this, various image processing is applied in copying, and copying is performed.

  When such copiers are connected to each other by a network or a dedicated cable, the image data stored in a storage device such as an HDD provided in these devices is transferred to another image processing device for output, There is a system that manages the increase / decrease in output jobs and equally divides the load (see Patent Document 2). For example, if the stored image data is output together with another image processing apparatus, the output efficiency can be improved and the output time can be shortened.

  In addition, the image data copied as described above may be taken up by a server or the like and backed up as data. In this case, when the backed up data is output again, it may be output by the same image processing apparatus (such as a copying machine) taken out or may be output again by another device.

  However, the color space represented by the image data stored in the storage device is a device-specific color space (see Patent Document 3). For example, in the case of a device that has four toner colors for image formation in a print unit and that develops four colors simultaneously by arranging four drums for that purpose, in order to absorb the timing due to the difference in the positions of the four drums Each color is transferred according to the deviation. Further, the color material of the toner at this time is unique to the device, and the color space that can be reproduced by the color material is determined, and the reproduction range also changes depending on printer characteristics such as development. For this reason, the color space may be a device-specific color space (a color space suitable for printer characteristics).

  In that case, since it is a device-specific color space, when it is output using backed-up image data for compatibility with other devices, the appearance will change (the output color will change). There is a flaw that often happens.

  If the image data stored in the storage device is a standard color space (for example, RGB space), the print system sends color space data specific to the printer for the PostScript file to the image processing device. In such a case, there is a problem that it becomes impossible to cope.

It is not only the color space that is unique to the device. The edge characteristics that the printer can reproduce differ depending on the dot reproducibility of the printer and the resolution of the engine. Therefore, the spatial frequency of the image may not be reproduced. Further, in order to obtain a stable output, pattern formation such as dithering is performed by gradation processing, which may also reduce the spatial frequency held by the image.
JP 2001-223828 A JP 2001-251522 A JP-A-6-054176

  The present invention has been made in consideration of the above-described circumstances, and solves the above-described problems and constructs an image processing apparatus that supports both the standard color space and the color space according to the characteristics of the printer unit. In addition, an object of the present invention is to provide an image processing apparatus capable of constructing image processing that supports spatial frequency characteristics corresponding to the spatial frequency and printer characteristics with respect to standard data and effectively utilizing the stored image data.

  In order to solve the above problems, the invention described in claim 1 includes an image reading unit that reads a document, a scanner correction unit that corrects the read image signal according to characteristics of predetermined standard data, Storage means for storing the image data corrected by the scanner correction means, printer correction means for correcting the image data stored in the storage means in accordance with the characteristics of the printer output device, and correction by the printer correction means. An image processing apparatus having a printer output unit for forming an image of the received image signal on paper or the like, wherein the scanner correction unit includes a first filter processing unit for correcting the MTF characteristic to a characteristic of standard data, and the printer The correction means includes second filter processing means for correcting the MTF characteristics to match the characteristics of the printer output device. To.

  According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, when the image reading unit generates a color signal, the scanner correction unit converts the color space represented by standard data into a color space. The one-color conversion means and the printer correction means include second color conversion means for converting into a color space that can be output by a printer output device.

  According to a third aspect of the present invention, in the image processing apparatus according to the second aspect, the color space represented by the first color converting means is a standard color space independent of a device.

  According to a fourth aspect of the present invention, in the image processing apparatus according to the second aspect, the color space represented by the first color conversion means is a standard color space determined so as to be shared between different models. It is characterized by.

  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 second filter processing means performs only enhancement processing.

According to the present invention, each of the scanner correction unit and the printer correction unit has a filter processing function, thereby adjusting the spatial frequency characteristic from the reading characteristic to the standard image data and the space from the standard image data to the printer characteristic. The frequency characteristic can be adjusted.
Thus, data stored as standard image data can be subjected to image processing without being aware of the spatial frequency characteristics of the device, and image data can be exchanged between different models.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of a digital copying machine according to the present embodiment, and FIG. 2 is a diagram illustrating a flow of image data according to the present embodiment. Here, the digital copying machine is a copying machine or an image processing system for carrying out the present invention, and is a so-called multifunction machine.

  First, referring to FIG. 1, the outline of each part of the digital copying machine and the contents of a series of processes from reading the original to printing out when copying the original will be described.

  The functions of the digital copying machine are roughly divided into an engine unit 2 and a printer controller unit 3. Since the digital copying machine implements the image processing system of the present invention, the digital copying machine performs predetermined processing as described later based on the image data.

First, the entire engine unit 2 is controlled by the engine controller 20.
In the engine unit 2, the reading unit 12 is an image reading device that reads an image of a document, and the image of the document is read as color image data separated into R, G, and B and sent to the scanner correction unit 13. FIG. 3 is a detailed processing flow of the scanner correction unit 13.

  In the scanner correction unit 13, the scanner γ correction unit 4 corrects the γ characteristics of the scanner with respect to the R, G, B color image data, and the first filter processing unit 5 performs filter processing such as smoothing and MTF correction. Then, the first color space conversion unit 6 converts the color space represented by the reading unit 12 into a standard color space (for example, a standard RGB, Lab, or Yuv color space).

  At this time, the color image data obtained by the reading unit 12 enters the image area separation unit 201 to extract characteristic portions of the image, for example, detect edges, colors, white background, halftone dots, etc. The detected result is passed to the first filter processing unit 5 and the first color space conversion unit 6. Using the detection result, characteristic image processing for each extracted portion, for example, in the first filter processing unit 5, smoothing processing is performed by processing different from other areas in areas detected as halftone dots. Or smoothing is performed so that moire of halftone dots is not generated.

Here, the standard color space in the first color space conversion unit 6 may be a device dependent (depending on the type of device) color space (RGB, CMY), or a device independent. It may be a color space (sRGB) that does not depend on the type of device.
However, especially in the case of a device-dependent color space, this color space is the same color space (for example, a standard sRGB space, Lab space, It may be corrected to a dedicated color space system that can be shared between different devices.

  Returning to FIG. 3, the image data converted into the standard color space by the first color space conversion unit 6 is compressed by the compressor 8. For example, when the compressor 8 has a fixed length and the image data is 8 bits for each color, the image data is converted into color data for each color n bits (n ≦ 8).

In this way, the image data compressed by the scanner correction unit 13 passes through the general-purpose bus 9 and the print controller 10 of the image data, and then temporarily passes through the semiconductor memory 10b, which is an independent storage medium for each color. And sent to the storage device 11 for storage. At this time, the storage device 11 is a large-capacity storage medium such as a hard disk, and can store a plurality of pages instead of a capacity of only one page of a document.
Thus, the image data corrected by the scanner and corrected in the standard color space is stored. Here, when it is desired to obtain an image stored from an external device (for example, PC) 25, the data converted into the standard color space can be distributed in the color space as it is.

Next, the image data stored in the storage device 11 is sent again to the printer correction unit 15 via the general-purpose bus 9 for image data. FIG. 4 is a diagram showing a detailed processing flow of the printer correction unit 15.
First, since the image data stored in the storage device 11 is compressed, the decompressor 402 converts the image data into 8-bit data for each color again. Thereafter, the second filter processing unit 301 performs filter processing in order to correct the MTF characteristics and dot reproducibility of the printer, and in accordance with the image quality mode transferred from the image processing apparatus.

  Here, the above-mentioned image quality mode is, for example, a mode in which output that emphasizes character quality or a mode in which output that emphasizes image quality is set in advance by a user (user), and depending on the setting contents To form an image. For example, in the second filter processing unit 301 here, the MTF characteristic is strongly emphasized in the mode in which the character quality is emphasized, or is not so emphasized in the operation in the mode in which the output is emphasized in the picture quality. A process having an MTF characteristic is applied so that an image is smoothly formed by smoothing.

  Here, if the first filter processing unit 5 generates standard data so as not to interfere with a dither pattern or the like at a spatial frequency, the second filter processing unit 301 performs smoothing on image data. It is not necessary to perform a filtering process that drops the MTF as in the process, and it is only necessary to perform an emphasizing process that restores only the degradation of the MTF that has dropped due to engine pattern formation. In this way, depending on the definition of the spatial frequency characteristics in the standard data, the second filter processing unit 301 at the subsequent stage needs to consider only emphasis.

  After the processing by the second filter processing unit 301, the data is transferred to the second color space conversion unit 302 and converted into a color space corresponding to the printer characteristics. A general color printer apparatus forms images with cyan, magenta, yellow, and black toners, and a color space that can be reproduced is determined by the color appearance of the toners. Therefore, the second color space conversion unit 302 converts standard color space data into such printer-specific color space, CMYK data.

  The data converted into CMYK data by the second color space conversion unit 302 is subjected to scaling processing by the scaling unit 303. This is executed in response to, for example, a user who operates in advance when reading a copy image enlarges / reduces the magnification set from the operation panel of the image processing apparatus.

  Thereafter, the printer γ correction unit 16 performs γ correction according to the characteristics of the printer unit, and the halftone processing unit 17 performs halftone processing according to the characteristics of the print image forming unit 19. At this time, the edge portion of the image is detected by the edge detection unit 401 using the data after scaling. The detection result is transferred to the printer γ correction unit 16 and the halftone processing unit 17, and the characteristics of the image are changed by changing the printer γ, the halftone processing method, or the halftone processing parameters according to the result. Correction according to is performed.

  In this way, the image data corrected by the printer correction unit 15 forms an image on a medium such as transfer paper by the print image forming unit 19 serving as a printer engine and outputs the image. In addition to the electrophotographic method, the printing method of the print image forming unit 19 can use various methods such as an inkjet method, a sublimation type thermal transfer method, a silver salt photography method, a direct thermal recording method, and a melt type thermal transfer method. .

  The FAX controller 21 shown in FIG. 1 controls the FAX function of the digital copying machine, and transmits / receives image data to / from a predetermined network such as a telephone line. The FAX controller 21 has a built-in compressor / decompressor, and compresses / decompresses image data to be transmitted / received. As this compression method, a method used in general FAX such as MH / MR is used. A network interface controller (NIC) 22 is an interface for connecting the digital copying machine to a network such as a LAN.

  Here, FIG. 5 shows a flow of image data when outputting as a printer output from an external device (for example, PC) connected to a network or the like. The flow of the image data shows the flow after being stored in the storage device 11, and the flow until the image data is stored in the storage device 11 has been described above, and is therefore omitted.

  First, image data transmitted from the external device 25 is transmitted to the printer controller 10 through the NIC 22. Thereafter, the printer controller 10 sends the data to the storage device 11 via a temporary storage memory attached to the printer controller 10. After that, as soon as the print imaging unit 19 is ready for printing, the image data stored in the storage device 11 is sent to the print imaging unit 19 via the memory 10b and the printer correction unit 15, and is transferred to a medium such as transfer paper. An image is formed and output.

  At this time, if the image data sent as the printer data is CMYK data conscious of printer image formation such as a PostScript (PS) file, the printer correction unit 15 does not perform processing. For example, in the case of image data that has been processed up to halftone processing with CMYK data, the printer correction unit 15 sends the image data to the print image forming unit 19 without performing any processing. However, when the image is transferred from the external device 25 in a state where γ processing according to the printer characteristics is not performed, the printer correction unit 15 is used to perform processing such as γ processing and gradation processing.

As another case, a case where the image data sent from the external device 25 or the like is a standard color space, for example, RGB data will be described.
In such a case, since the image data stored in the storage device 11 is standard color space data and also RGB data, the printer correction unit 15 performs the process such as color conversion as described above. Processing is performed together in the same flow. In this way, when image data for a printer is sent in a standard color space, the processing is the same as copying. At this time, the same function is shared.

  Here, the stored image data can also be acquired by the external device 25 or the like via a network or the like. As an example at this time, a case where image data stored in the storage device 11 is transferred to the external device 25 will be described.

  The image data stored in the storage device 11 is sent to the data format conversion device 24 via the general-purpose bus 9. The data format conversion device 24 converts the image format, resolution, etc. that the external device 25 wants to receive. For example, it is assumed that the image data stored in the storage device 11 is 600 dpi RGB data, and this data is received by the external device 25 in the 200 dpi JPEG 2000 format. A processing flow of the data format conversion device 24 at this time will be described with reference to FIG.

  First, the sent image data is sent to the decompressor 32 through the input port 31. As described in the previous example, when the image data stored in the storage device 11 is compressed, it is decompressed by the decompressor 32. Thereafter, the resolution converter 33 converts 600 dpi data into 200 dpi. The image data converted to 200 dpi is sent to the color space converter 34. At this time, the RGB data is converted into a color space (for example, Yuv) that can be used for JPEG2000. However, for example, when the stored image data is stored in a usable color space, the color space converter 34 does not perform processing.

  After that, the format conversion / compressor 35 converts the format to the JPEG2000 format, and then sends it to the output port 36. The general-purpose bus 9 transmits the data from the printer controller 10 to the external device 25 through the NIC 22 via the network. .

Further, as described above, the storage device 11 is temporarily stored at the time of each processing such as copying and printing, and at the same time is stored in the mass storage device. Thereby, such reuse becomes possible after output.
For example, when RGB data is to be output as a print and output to paper becomes difficult due to some trouble, a case will be described in which output is attempted with another device. If this other device supports the same color space as the target image data, it is directly transferred to the target device through the NIC 22.

  However, there is a case where data is transferred to a printer device that supports only a device-specific color space such as CMYK. In that case, the color space is converted using the printer correction unit 15. First, the conversion parameter from the standard color space to the device specific color space is downloaded. The download source is prepared in a server with information (parameters) for the target device to convert from the standard color space, a device that prints an image on behalf of the device, or a device in this embodiment Has been.

The conversion parameter is set in the second color space conversion unit 302 to perform conversion to the destination color space. Thereafter, the data is stored in the storage device 11, and the stored data is transferred to the printer device through the printer controller 10, the NIC 22, and the network.
Thus, by converting into the color space of the target printer device, the stored image data can be output by another device. At this time, the second filter processing unit 301 can perform a filtering process according to the printer characteristics of the device to correct the difference in the appearance of the image as the device in the output image.

1 is a block diagram illustrating a configuration of a digital copying machine according to an embodiment. It is a figure which shows the flow of the image data in this embodiment. It is a detailed processing flow of a scanner correction part. 3 is a detailed processing flow of a printer correction unit. FIG. 5 is a diagram illustrating a flow of image data when output as a printer output from an external device connected to a network or the like. It is a figure which shows the processing flow of a data format conversion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Engine part, 12 ... Reading unit, 13 ... Scanner correction part, 201 ... Image area separation part, 4 ... Scanner gamma correction part, 5 ... First filter processing part, 6 ... First color space conversion part, 8 ... Compression 15 ... printer correction unit 402 ... decompression unit 301 ... second filter processing unit 302 ... second color space conversion unit 303 ... magnification changing unit 401 ... edge detection unit 16 ... printer γ correction unit 17 ... halftone processing unit, 19 ... print image forming unit, 20 ... engine controller, 21 ... FAX controller, 3 ... printer controller unit, 10 ... printer controller, 10b ... (semiconductor) memory, 11 ... storage device, 22 ... NIC, 24 ... Data format conversion device, 31 ... Input port, 32 ... Decompressor, 33 ... Resolution converter, 34 ... Color space converter, 35 ... Format converter / compressor, 36 ... Output Power port, 9 ... general purpose bus, 25 ... external device.

Claims (5)

  Image reading means for reading a document, scanner correction means for correcting the read image signal in accordance with characteristics of predetermined standard data, storage means for storing image data corrected by the scanner correction means, Printer correction means for correcting the image data stored in the storage means according to the characteristics of the printer output device; and printer output means for forming an image of the image signal corrected by the printer correction means on paper or the like. In the image processing apparatus, the scanner correction unit includes a first filter processing unit that corrects MTF characteristics that match the characteristics of standard data, and the printer correction unit corrects MTF characteristics that match the characteristics of the printer output device. And a second filter processing means.   2. The image processing apparatus according to claim 1, wherein when the image reading unit generates a color signal, the scanner correction unit includes a first color conversion unit for converting into a color space represented by standard data, and the printer correction. An image processing apparatus characterized in that the means includes second color conversion means for converting into a color space that can be output by a printer output device.   3. The image processing apparatus according to claim 2, wherein the color space represented by the first color conversion means is a standard color space independent of a device.   3. The image processing apparatus according to claim 2, wherein the color space represented by the first color conversion means is a standard color space determined so as to be shared between different models.   5. The image processing apparatus according to claim 1, wherein the second filter processing unit performs only enhancement processing. 6.