JP2006165660A - Calibration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration system for facilitating color correction in a direct print. <P>SOLUTION: The calibration system provided with an image imaging apparatus and an image forming apparatus capable of directly transceiving image data is characterized in that a correction coefficient for calibration is obtained from correction image data acquired by photographing a color patch pattern outputted from the image forming apparatus by using the image imaging apparatus so as to correct optional print image data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a color correction process for outputting image data received from an image pickup apparatus from the image forming apparatus with suitable color reproduction, and an image pickup apparatus and an image forming apparatus for performing the color correction process. It relates to a calibration system.

In recent years, digital cameras and printers have been improved in functionality, and products, print systems, and services that respond to various needs of users are being developed. Among them, direct print systems that can send data directly from a digital camera or the like to an image forming apparatus and easily obtain a hard copy without using a personal computer (PC) driver have become widespread (for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-131838

  However, the color of the photographed image varies greatly depending on the image processing inside the digital camera and the characteristics of the CCD mounted thereon. In addition, color management and color correction are not performed between the input device and the output device so that a hard copy that is always reproduced in a preferable color can be obtained. Therefore, it is difficult to obtain a hard copy reproduced with a preferable color in the direct print system.

  Further, in the direct print system, there has never been a system that absorbs the color difference of the input device on the output device side. Against this background, a method for easily obtaining a hard copy reproduced with a suitable color directly from a digital camera is required.

  The present invention has been made paying attention to the above points. It is possible to easily obtain a hard copy processed into a suitable color, obtain a hard copy without using a PC, and shoot a color patch. An object of the present invention is to provide a calibration system that can be simplified and can easily output a color-matched image even from a remote place.

  The present invention includes the following configuration as a means for solving the above-described problems.

  (1) In a calibration system including an image pickup apparatus and an image forming apparatus, an image forming unit that prints a predetermined color patch pattern on the recording medium from the image forming apparatus, and the image forming unit prints on the recording medium Image pickup means for picking up a color patch pattern as an image signal by the image pickup apparatus, and recording means for recording the picked-up image signal in the image pickup apparatus, the image pickup apparatus and the image forming apparatus being communicable The two devices obtain an optimum correction coefficient from a communication unit capable of directly transmitting and receiving data, an image previously captured by the image capturing device, and a color patch pattern captured by the image forming unit. Correction coefficient calculation means, and image correction means for setting the correction coefficient to correct the captured image. Calibration system.

  According to the present invention, when the image forming apparatus selects an appropriate parameter and performs a calibration process, it is possible to absorb the difference in the color of the input device, and a hard copy processed into a suitable color can be easily obtained. It becomes possible to obtain it.

  Further, it is possible to obtain a hard copy without using a PC.

  Further, by storing model information and color correction parameters in the storage device, it is possible to simplify the shooting of color patches.

  Furthermore, it is possible to easily output a color-matched image even from a remote place.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram for explaining the overall configuration of a data processing system according to an embodiment of the present invention.

  In FIG. 1, reference numeral 101 denotes an image pickup apparatus (hereinafter referred to as a digital camera), and reference numeral 102 denotes an image forming apparatus (hereinafter referred to as a printer). Reference numeral 103 denotes an interface for transmitting and receiving data between the digital camera 101 and the printer 102 described later. Reference numeral 104 denotes a color patch pattern printed on paper from a printer described later.

  Reference numerals 105, 106, 107, 108, and 109 are image data captured using the digital camera 101, and are recorded on a recording medium inside the digital camera 101. The image data 105, 106, 107, and 108 are obtained by photographing the color patch pattern 104 printed on the paper with all white balance (hereinafter referred to as WB) of the digital camera 101, and each WB is different. . Hereinafter, 105, 106, 107, and 108 are correction image data. Of course, the number of white balances of the digital camera is not limited.

  The image data 109 is image data to be output using the data processing system of the present invention, and is image data captured in advance using the digital camera 101. Hereinafter, 109 is image data for printing.

  FIG. 2 is a block diagram illustrating a control configuration of the image forming apparatus according to the embodiment of the present invention.

  In FIG. 2, reference numeral 101 denotes a digital camera, which sends arbitrary image data captured in advance and color patch pattern data (described later) for performing correction processing to the printer 102.

  The printer 102 includes the following configuration.

  The printer 102 is roughly divided into an image processing unit 201 and a printer engine 211 that performs actual image formation based on image signals sent from the image processing unit 201.

  Hereinafter, main configurations and operations of the image processing unit 201 will be described.

  In the image processing unit 201, 103 is an interface that controls transmission / reception of image data with the digital camera 101, and 202 is a reception buffer that holds input image data.

  103 can be directly transmitted to and received from a printer without using a printer driver of a personal computer or various intermediary devices (for example, communication means such as a network, the Internet, USB, IEEE 1394, IrDA, Bluetooth, compact flash (registered trademark) card, SD Via a recording medium such as a card).

  In the object generation unit 203, image data input from the digital camera 101 is converted into intermediate information (hereinafter referred to as an object) and stored in the object buffer 204.

  At this time, if the image data is correction image data described later, a WB correction value and a color correction table are calculated. In the case of print image data, the data correction unit 212 performs various image processing including color correction using a color correction table described later.

  Next, based on the object stored in the object buffer 204, the rendering unit 205 generates a bit image to be rendered.

  At this time, the dither processing unit 207 performs halftone processing to reduce the output gradation.

  The generated bit image is stored in the band buffer 206.

  In this way, the bit image stored in the band buffer 206 is sent to the printer engine 211 and formed on the recording medium.

  A central processing unit (CPU) 209 determines and controls various processes according to a program stored in the ROM 208. A ROM (read only memory) 208 stores various control programs 208a including a program for controlling the system of the present invention and color patch pattern data 208b described later.

  210 stores data, status information, color patch pattern data 208b, a WB correction value, and a color correction table for the CPU 209 to perform determination control of each process according to a program stored in the ROM 208, and for WB correction and color correction. A RAM (Random Access Memory) used as a work area.

  Further, the data correction unit 212 creates a WB correction value and a color correction table from the image signals R, G, and B values of the color patch pattern photographed by the digital camera 101, and generates a WB correction area 210b and a color correction table area of the RAM 210. Store in 210c.

  FIG. 3 is a flowchart of the simple calibration system of the present invention.

  When the printer 102 receives a command for printing the color patch pattern 104, the color patch pattern data such as the input density level is stored in the ROM 208, and the color patch pattern 104 is printed through the printer engine 211 (S301). The printer 102 enters a standby state for image data, and directly communicates when the image data is transmitted from the digital camera 101 through the interface 103 (S302).

  As an embodiment of the present invention, the image data uses an Exif (Exchangeable image file format). Exif is an image format in which unique information for a digital camera based on the existing general-purpose image format TIFF and JPEG is embedded. However, in this embodiment, Exif is used as the image data format, but any image format that includes unique information such as the shooting model and shooting conditions and can be acquired may be used.

  From the received image data, various information such as the model information of the digital camera and photographing conditions including white balance are acquired (S303).

  In order to determine whether the image data is an image obtained by capturing the color patch pattern 104, DP (dynamic programming) matching is performed as an example of this embodiment (S304). A determination is made based on the matching result of the received image data (S305). If the image data is correction image data 105, 106, 107, 108, a WB correction value used for WB correction described later is calculated (S305). ).

The WB correction value is obtained from each image signal R, G, B value of the white paper portion of the color patch pattern data. For example, the image signal value of the paper white portion of the correction image data 105 has a value of (R, G, B) = (250, 240, 230), and the paper white portion of the paper is (R, G, B). ) = (255, 255, 255), an offset value is obtained for each image signal and set as a WB correction value. The offset value in this case is
Thus, the WB correction value for R is 2%, the correction value for G is 6%, and the correction value for B is 10%. These calculated values are stored in the WB correction area 210b for each WB.

  In the WB correction area 210b, WB correction corresponding to the WB of the correction image data 105 is performed on the received correction image data 105 using the WB correction value calculated by the WB correction value calculation means ( S306). In the WB correction, the WB correction value is added for each image signal.

  In the color correction table area 210c, a color correction table (to be described later) is calculated from the density level of each patch of the image data subjected to WB correction and the image signal level of the color patch pattern data 208b stored in the ROM. Stored (S307).

  On the other hand, if the image data received in S305 is the printing image data 109, it is determined whether the WB correction value and color correction table corresponding to the WB of the printing image data 109 are stored in the RAM 210 (S308).

  If not, an error is returned and the process returns to S301.

  When it is confirmed that the image is stored, the above WB correction is performed on the print image data 109 (S309).

  Color correction is performed on the print image data 109 after WB correction from the color correction table corresponding to WB (S310).

  The print image data 109 that has been color-corrected and reproduced in a suitable color is subjected to image processing in the image processing unit 201 inside the printer 102 and printed on paper via the printer engine 211.

  FIG. 4 is an example of a color patch pattern.

  A patch pattern of each color is formed on the paper with R, G, B print areas and paper white portions and with a sufficient number of halftone input levels to obtain the color correction parameters (for example, R, G , B in each region, the input level is 10, 50, 120, 200, 255).

  This color patch pattern is printed on paper by a command from a digital camera or printer.

  When photographing this color patch pattern with a digital camera, a guide frame may be provided on the paper so that it can be photographed in a prescribed size.

  FIG. 5 is an example of a color correction table.

  The image data received by the printer 102 has an 8-bit value for each color of the image signals R, G, and B.

(A) is a correction image received by the printer 102 after the digital camera 101 captures the image signal level in color patch pattern data R stored in the ROM and the color patch pattern 104 printed on the paper by the printer 102. A curve representing an image signal level in R of the data 105;
(B) is a curve representing a color correction table in R;

The color patch pattern 104 printed on the paper with R _in (10, 50, 120, 200, 255) _{in the} color patch pattern data R _in is captured by the digital camera 101 and received when received by the printer 102. _out (8, 40, 90, 170, 255).

A color correction table (b) in which R _in (10, 50, 120, 200, 255) becomes R ′ (12, 60, 150, 230, 255) is obtained from the change amount. That is,
R ′ = R _in (R _in −R _out )
It becomes.

  As an example of the present invention, in this embodiment, linear interpolation is used for table interpolation between patches.

  The above-described color correction table is obtained for image signals G and B by the same means.

  The image signals R, G, and B of the image data 109 received by the printer 102 are subjected to color correction for each image signal by a color correction table obtained from the above means.

  Of course, the color correction may be performed with the image data in the state of the image signals C, M, Y, and K. In this case, however, a color correction table must be created for each of the image signals C, M, Y, and K.

  When operating the mechanism of one embodiment of the present invention, if there is a calibration function for setting the image forming apparatus in a predetermined state, the image forming apparatus is set in a predetermined state using the calibration function.

  When there is a display device, guidance of each process of the data processing system of the present invention, thumbnail display of received images, selection of input device model, and fine adjustment of color correction may be performed.

  FIG. 6 is an example of a case where guidance of each process according to an embodiment of the present invention is displayed on a display device.

  (A) is displayed when printing is performed using the system of the present invention. When the start button is pressed, the printer 102 proceeds to S301 in which a color patch pattern is printed on paper.

  (B) is displayed during printing.

  (C) is displayed after printing is completed, prompts the user to shoot the color patch pattern 104, and proceeds to S302 when the OK button is pressed.

  (D) is displayed in the image data standby state in S302.

  (E) is displayed when image data is transmitted and received.

  (F) is displayed after the completion of S307 when the image data is 104, 105, 106, 107, and when the OK button is pressed, the process proceeds to S302.

  (G) is displayed when it is Yes in S308. If the OK button is pressed, the process proceeds to S309.

  (H) is displayed in the case of No in S308, and proceeds to S302 when the OK button is pressed.

  (I) is displayed when all the steps of the present invention are completed.

  When the image pickup apparatus is a portable terminal (such as a mobile phone, a PDA, or a notebook PC) that has a communication function and has a built-in digital camera, and the image forming apparatus has a storage device, the recording medium reads at least from the received data Stores model information, WB correction values, color correction parameters, and the like of the input device.

  A portable terminal incorporating a digital camera when model information and photographing conditions are read from image data received by the image forming apparatus, and a color correction table meeting the conditions is stored in the storage device in the image forming apparatus The color correction can be performed by omitting the shooting and transmission of the color patch pattern printed on the paper and the calculation of the WB correction value and the color correction table in the image forming apparatus. Images can be easily output.

It is a figure explaining the whole structure concerning the data processing system of one embodiment in the present invention. 1 is a block diagram illustrating a configuration of an image recording apparatus and an image processing apparatus according to an embodiment of the present invention. It is a flowchart of the data processing system in this invention. It is a figure which shows an example of the color patch pattern in this invention. It is a figure which shows an example of the color correction table in this invention. It is a figure which shows an example at the time of displaying each process of the data processing system of one Embodiment in this invention on a display apparatus.

Explanation of symbols

101 Digital Camera 102 Printer 103 Interface 201 Image Processing Unit 202 Reception Buffer 203 Object Generation Unit 204 Object Buffer 205 Rendering Unit 206 Band Buffer 207 Dither Processing Unit 208 ROM
209 CPU
210 RAM
211 Printer Engine 212 Data Correction Unit

Claims (2)

In a calibration system comprising an image pickup device and an image forming device,
Image forming means for printing a predetermined color patch pattern on the recording medium from the image forming apparatus;
Image pickup means for picking up the color patch pattern printed on the recording medium by the image forming means as an image signal by the image pickup device, and recording means for recording the picked-up image signal in the image pickup device;
The image capturing apparatus and the image forming apparatus can communicate with each other, and the two apparatuses can directly transmit and receive data;
Correction coefficient calculation means for obtaining an optimal correction coefficient from an image captured in advance by the image capturing device and a color patch pattern captured by the image forming means;
A calibration system comprising: an image correction unit that sets the correction coefficient and corrects the captured image. The image pickup device is a mobile communication device, and the image forming device includes a display device and a storage device,
The calibration system according to claim 1, wherein the image forming apparatus stores the correction coefficient calculated by the correction coefficient calculation unit in the storage device.