JP2008236672A - Camera, and image correction value calculation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain correction information meeting output characteristics of an output device. <P>SOLUTION: An image controller 13 reads the image of a color chart from a color chart image memory 161, outputs the read image to a display 2, images the color chart being displayed on the display 2, and captures an image including the color chart. An image recognizer 17 extracts, from the image including the color chart, extraction images within a range corresponding to the color chart and a color error judgment unit 18 compares the extracted extraction images with the color chart, calculates correction information for correcting a photographic image to be output to the display 2, and records the calculated correction information in a look-up table (LUT) 163. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a camera that captures and acquires an image, and an image correction value calculation method for correcting an image acquired by the camera.

  The following image correction apparatus is known. This image correction apparatus captures a reference image displayed on a display with a camera and analyzes the acquired captured image. And image correction information is produced | generated based on the analysis result of a picked-up image (for example, patent document 1).

JP 2000-270338 A

  However, in the conventional apparatus, the reference image displayed on the display is captured by the camera to obtain the captured image. However, when the size of the reference image in the captured image is small, the analysis accuracy of the captured image is low. The accuracy of the image correction information may also be reduced.

The present invention records a captured image obtained by capturing a subject image on a recording medium, records a reference image for measuring output characteristics of the output device on the recording medium, reads the reference image, and outputs the reference image to the output device. Capturing an image of the reference image output to the output device, obtaining an image including the reference image, extracting an extracted image corresponding to the reference image from the image including the reference image, and extracting the extracted image; Comparing with a reference image, calculating correction information for correcting a captured image output to the output device, correcting the captured image using the correction information, and outputting the corrected captured image to the output device And
In the present invention, it is preferable to urge the user to take an image including the reference image so that the reference image has a predetermined size in the image including the reference image.
Further, the size of the reference image included in the acquired image including the reference image is determined, and when the size of the reference image included in the image including the reference image is not a predetermined size, the user is notified. On the other hand, an explanation regarding the size of the reference image may be output to prompt re-shooting.
Furthermore, a color conversion table in which color information before correction and color information after correction are associated may be recorded on the recording medium as correction information.

  According to the present invention, highly accurate image correction information can be generated.

  FIG. 1 is a diagram schematically showing a connection example between a camera and a display as an output device in the present embodiment. The camera 1 functions as an image output device, and is connected to a display 2 as an image display device via a video output line 3. The camera 1 in the present embodiment outputs the color chart P1 or the normal image P2 to the display 2 via the video output line 3 and displays it. The camera 1 is, for example, a digital camera, and the display 2 is, for example, a high-definition television. The video output line 3 may be wired or wireless.

  FIG. 2 is a diagram schematically showing a mode switching switch provided for the camera 1 to output either the color chart P1 or the normal image P2 to the display 2. In the camera 1, the image output to the display 2 is switched by switching the target of the video output V1 by the switch mechanism S1. That is, the color chart P1 is video output (V1) by switching the switch mechanism S1 to the terminal b side, and the normal P2 is video output (V1) by switching the switch mechanism S1 to the terminal a side. As will be described later, when the color chart P1 is video output (V1), a correction value of an image that matches the display characteristics (output characteristics) of the display 2 is calculated.

  FIG. 3 is a block diagram showing a configuration of an embodiment of the camera 1 in the present embodiment. The camera 1 includes a lens 11, an image sensor 12, an image controller 13, a system controller 14, a memory controller 15, a color chart image memory 161, an image memory 162, and a LUT (Look Up Table) 163. A switch mechanism S1, an image recognizer 17, a color error determiner 18, a color corrector 19, and a monitor 20. Further, the camera 1 outputs an image from the video output V1 to the display 2 connected by the video output line 3.

  The lens 11 is composed of a plurality of optical lens groups, but is represented by a single lens in FIG. The image sensor 12 is an image sensor such as a CCD or a CMOS, for example, and captures a subject image formed by the lens 11 to acquire an image. Then, the acquired image data (image data) is output to the image controller 13. The image controller 13 performs various image processing on the input image data and then outputs the processed image data to the memory controller 15. The memory controller 15 records the input image in the image memory 162. The image (captured image) recorded in the image memory 162 corresponds to the normal image P2 displayed on the display 2.

  The color chart image memory 161 is a memory in which an image (color chart image) of the color chart P1 to be displayed on the display 2 described above is recorded. This color chart image corresponds to a reference image for measuring output characteristics of the output device, that is, display characteristics of the display 2. The LUT 163 is a memory for recording correction information corresponding to the display characteristics of the display 2 calculated by processing to be described later.

  The memory controller 15 controls the writing of data to the color chart image memory 161, the image memory 162, and the LUT 163, and the reading of data from the color chart image memory 161, the image memory 162, and the LUT 163. As the color chart image memory 161, the image memory 162, and the LUT 163, for example, a flash memory as a recording medium is used.

  As described above with reference to FIG. 2, the switch mechanism S1 switches the output target image to be subjected to the video output V1 between the color chart P1 and the normal image P2. In the present embodiment, the user can instruct which image is displayed on the display 2 by switching the display mode, and the image controller 13 instructs the switch mechanism S1 based on the instruction from the user. Instruct the switch to switch. For example, the camera 1 includes a color chart display mode for displaying the color chart P1 and a normal image display mode for displaying a normal image as display modes.

  When the color chart display mode is selected as the display mode by operating an operation member (not shown) by the user, the memory control unit 15 reads the color chart image from the color chart image memory 161 and performs image control. Output to the device 13. Then, the image controller 13 switches the switch mechanism S <b> 1 to the b side and outputs a color chart image to the image recognizer 17. Here, the image recognizer 17 to the color corrector 19 output the color chart image as a video output V1 without performing processing. As a result, the color chart P1 is displayed on the display 2.

  Thus, after displaying the color chart P1 on the display 2, the system controller 14 instructs the user to shoot the color chart P1 displayed on the display 2 using the camera 1. At this time, the system controller 14 issues a shooting instruction so that the size of the color chart P1 in the image becomes a predetermined size. Specifically, first, the system controller 14 displays a frame of a predetermined size on a monitor 20, for example, a rear liquid crystal monitor mounted on the back of the camera 1, and displays a through image on the monitor 20. The user is prompted to determine the composition so that the screen size of the display 2 becomes the size of the frame.

  For example, a frame 4a is displayed in the monitor 20 as shown in FIG. Then, as shown in FIG. 4B, a dialog 4b in which a message for prompting the user to take a picture so that the entire screen of the display 2 falls within the frame 4a is displayed. Thus, the user can take an image so that the screen of the display 2 has a predetermined size, and as a result, obtains an image so that the color chart P1 displayed on the display 2 has a predetermined size. Can do.

  When shooting is performed by the user and an image on the display 2, that is, an image including the color chart P1, is acquired, the image controller 13 determines the size of the color chart P1 in the image. For example, as shown in FIG. 5, the color chart P <b> 1 has points 5 a to 5 c indicating the end points of the color chart at the three corners, and the image controller 13 selects these points 5 a to 5 c from the image of the display 2. Extract 5c. Then, the image controller 13 calculates the distance between the points 5a and 5b, thereby calculating the width of the color chart P1 in the image of the display 2, and calculates the distance between the points 5b and 5c. Thus, the height of the color chart P1 in the image of the display 2 is calculated.

  The image control unit 13 determines the size of the color chart P1 in the image of the display 2 based on the calculated width and height of the color chart P1. Then, when the image controller 13 determines that the size of the color chart P1 is less than a predetermined size, the system controller 14 determines the composition so that the screen becomes larger for the user. Then, the user is prompted to take a picture again, and the image on the display 2 is acquired again.

  On the other hand, when it is determined that the size of the color chart P1 is equal to or larger than a predetermined size, the user is prompted to determine the composition so that the screen is smaller and to re-shoot. The image on the display 2 is acquired again. That is, when the size of the color chart P1 is not a predetermined size, the system controller 14 outputs an explanation to the user so that the size of the color chart P1 becomes a predetermined size. Encourage re-shooting.

  When the image control unit 13 determines that the size of the color chart P1 is a predetermined size, the image control unit 13 outputs the image on the display 2 to the image recognizer 17. If the image controller 13 cannot extract the points 5a to 5c from the captured image, the image controller 13 displays the screen shown in FIG. Encourage shooting.

  When the image on the display 2 is input from the image control unit 13, the image recognizer 17 performs a trimming process on the image and extracts only a range where the color chart P <b> 1 is captured from the image. That is, an extracted image (photographing color chart image) is generated by excluding portions other than the color chart P1, such as the frame of the display 2 included outside the color chart P1. Then, the generated photographing color chart image is output to the color error determiner 18.

  The color error determination unit 18 compares the input photographic color chart image with the color chart image recorded in the color chart image memory 161, and measures the color error of the photographic color chart image with respect to the color chart image. Then, the color error determiner 18 calculates a correction value for correcting the measured color error. That is, a correction value for correcting the photographic color chart image to the same color as the color chart image is calculated.

  Specifically, the color error determination unit 18 acquires the RGB value of a pixel in the color chart image, and acquires the RGB value of the pixel corresponding to the position of the captured color chart image. Then, an error of the RGB value of the pixel is calculated by taking the difference between the two acquired RGB values, and a correction value for correcting the error is calculated. By performing this process on all the pixels of the color chart image and the photographic color chart image, a correction value for correcting the color of the image in accordance with the display characteristics of the display 2 can be obtained.

  Then, the color error determiner 18 generates a color conversion table based on the calculated correction value, and records the generated color conversion table in the LUT 163 as correction information. For example, as shown in FIG. 6, a color conversion table in which the RGB values (input RGB values) of the photographic color chart image are associated with the corrected RGB values (corrected RGB values) is generated, and the LUT 163 is generated. Record. That is, the color error determination unit 18 calculates a color conversion table in which color information before correction and color information after correction are associated with each other as correction information, and records the correction information in the LUT 163.

  Next, processing when the normal image display mode is selected as the display mode by the user will be described. In this case, the memory control unit 15 reads a normal image from the image memory 162 and outputs it to the image controller 13. Then, the image controller 13 switches the switch mechanism S1 to the a side and outputs a normal image to the color corrector 19.

  The color corrector 19 reads the color conversion table described above from the LUT 163 and corrects each color (input RGB value) of the input normal image to a corresponding correction value (corrected RGB value). Then, color correction processing is performed on the normal image. That is, the color correction process is performed for each color included in the normal image, and the process is terminated when the processes for all colors are completed. Then, the color corrector 19 outputs the normal image after performing the color correction process to the Video output V1. As a result, the normal image P2 that has been corrected in accordance with the display characteristics of the display 2 can be displayed on the display 2. If the color correction unit 19 cannot obtain the correction value of the color included in the normal image from the color conversion table, the color correction unit 19 does not perform the color conversion process for that color.

  FIG. 7 is a flowchart showing processing of the camera 1 in the present embodiment. The process shown in FIG. 7 is executed as a program that is activated when the power of the camera 1 is turned on by the user.

  In step S10, the memory control unit 15 determines which of the color chart display mode and the normal image display mode is selected as the display mode. If it is determined that the color chart display mode has been selected, the process proceeds to step S20. In step S <b> 20, the memory control unit 15 reads a color chart image from the color chart image memory 161 and outputs it to the image controller 13. Then, it progresses to step S30.

  In step S30, the image controller 13 switches the switch mechanism S1 to the b side. Thereafter, the process proceeds to step S40, where the image control unit 13 outputs the color chart image to the image recognizer 17 and outputs the Video output V1. As a result, the color chart P1 is displayed on the display 2. Thereafter, the process proceeds to step S50.

  In step S50, the system controller 14 instructs the user to shoot the color chart P1 displayed on the display 2 using the camera 1. At this time, as shown in FIG. 4, the system controller 14 displays the frame 4a and the dialog 4b in the monitor 20, and takes an image so that the size of the color chart P1 in the image becomes a predetermined size. Give instructions. Thereafter, the process proceeds to step S60.

  In step S60, the image controller 13 determines whether or not shooting has been performed by the user. If the determination is affirmative, the process proceeds to step S70, and the image controller 13 extracts the points 5a to 5c indicating the end points of the color chart from the image on the display 2 as described above with reference to FIG. The size of the color chart P1 is determined. Thereafter, the process proceeds to step S80, and it is determined whether or not the determined size of the color chart P1 is a predetermined size.

  If a negative determination is made, the process proceeds to step S90, and the system controller 14 prompts the user to re-shoot the image on the display 2. That is, when it is determined that the size of the color chart P1 is less than the predetermined size, the user is explained to make the screen larger, and the user is prompted to determine the composition and re-shoot. Further, when it is determined that the size of the color chart P1 is equal to or larger than a predetermined size, the user is explained to make the screen smaller, and the composition is urged to be re-photographed. Even when the points 5a to 5c cannot be extracted from the captured image, the user is prompted to re-photograph the screen of the display 2. Thereafter, the process returns to step S60.

  On the other hand, when an affirmative determination is made in step S80, the image control unit 13 outputs the image on the display 2 to the image recognizer 17, and proceeds to step S100. In step S100, the image recognizer 17 performs a trimming process on the image on the display 2, extracts only the range in which the color chart P1 is reflected from the image, and uses the extracted captured color chart image as a color error determiner. 18 is output. Then, it progresses to step S110.

  In step S110, the color error determiner 18 executes a correction value calculation process described later in FIG. 8, calculates a correction value for correcting the above-described normal image, generates a color conversion table, and performs step S120. Proceed to In step S120, the generated color conversion table is recorded in the LUT 163 as correction information. Thereafter, the process proceeds to step S200, and the system controller 14 determines whether or not the power of the camera 1 is turned off by the user. If a negative determination is made, the process returns to step S10 and the process is repeated. On the other hand, if an affirmative determination is made, the process is terminated.

  Next, a process when the memory control unit 15 determines in step S10 that the normal image display mode has been selected by the user will be described. In this case, the process proceeds to step S <b> 130, and the memory control unit 15 reads a normal image from the image memory 162 and outputs it to the image controller 13. Thereafter, the process proceeds to step S140, and the image controller 13 switches the switch mechanism S1 to the a side, outputs a normal image to the color corrector 19, and proceeds to step S150.

  In step S150, the color corrector 19 reads the color conversion table described above from the LUT 163, and acquires correction values (corrected RGB values) corresponding to the colors of the input normal image (input RGB values). Thereafter, the process proceeds to step S160, and the color corrector 19 determines whether or not a correction value has been acquired. If the determination is affirmative, the process proceeds to step S170, and the color corrector 19 performs color correction processing on the normal image using the acquired correction value, and then proceeds to step S180. On the other hand, if a negative determination is made, the process proceeds to step S180 without performing color correction processing.

  In step S180, the color corrector 19 determines whether or not the processing in steps S150 to S170 has been completed for all colors included in the normal image. If a negative determination is made, the process returns to step S150 to repeat the process. On the other hand, if an affirmative determination is made, the process proceeds to step S190, and the color corrector 19 outputs the normal image after the color correction process from the Video output V1. As a result, the normal image P <b> 2 corrected according to the display characteristics of the display 2 is displayed on the display 2. Then, it progresses to step S200 mentioned above.

  FIG. 8 is a flowchart showing the correction value calculation process executed in step S110 in FIG. In step S210, the color error determiner 18 acquires the RGB value of one pixel in the color chart image. Thereafter, the process proceeds to step S220, and the color error determination unit 18 acquires the RGB value of the pixel of the photographic color chart image that corresponds in position to the pixel for which the RGB value has been acquired in step S210. Thereafter, the process proceeds to step S230, where the color error determination unit 18 calculates an error of the RGB value of the pixel based on both the acquired RGB values, and calculates a correction value for correcting the error. Thereafter, the process proceeds to step S240.

  In step S240, the color error determiner 18 stores the calculated correction value in the color conversion table, and proceeds to step S250. In step S250, it is determined whether or not the processing in steps S210 to S240 has been completed for all the pixels of the color chart image and the captured color chart image. If a negative determination is made, the process returns to step S210 to repeat the process. On the other hand, if a positive determination is made, the process returns to the process of FIG.

According to the present embodiment described above, the following operational effects can be obtained.
(1) An image of the color chart was output to the display 2, and the displayed color chart P1 was photographed to obtain an image. Then, a range including the color chart is extracted from the acquired image, and the correction value is calculated by comparing the extracted image with the color chart image. Accordingly, it is possible to acquire a correction value for bringing the displayed image close to the image quality of the original image according to the display characteristics of the display 2.

(2) Correction information based on the calculated correction value is recorded in the LUT 163 as a recording medium. Thus, once the correction value of the display 2 is calculated, the recorded correction information can be referred to thereafter, and the correction value need not be calculated each time.

(3) The captured image is corrected using the correction information and then output to the display 2. As a result, it is possible to output to the display 2 a photographed image that has been corrected in accordance with the display characteristics of the display 2.

(4) In photographing the color chart P1 displayed on the display 2, the frame 4a is displayed on the monitor 20, and the user is photographed so that the entire screen of the display 2 is within the frame 4a. The dialog 4b in which a message for prompting is written is displayed. Thus, the user can take an image so that the screen of the display 2 has a predetermined size, and as a result, obtains an image so that the color chart P1 displayed on the display 2 has a predetermined size. Can do.

(5) When the image of the display 2 is acquired, the size of the color chart P1 in the image is determined. When the size of the color chart P1 is not a predetermined size, guidance is provided to the user. To re-shoot. As a result, when the color chart P1 is not photographed in a size necessary for calculating the correction value, the user is encouraged to re-photograph and an image including the sufficiently large color chart P1. Can be obtained.

(6) A color conversion table in which color information before correction is associated with color information after correction is recorded as correction information. Accordingly, each color in the input captured image can be corrected to a color according to the display characteristics of the display 2 and displayed on the display 2.

-Modification-
The camera according to the above-described embodiment can be modified as follows.
(1) In the embodiment described above, an example is described in which the display 2 as a display device, for example, a high-definition television is used as an output device for outputting an image, and the color chart P1 or the normal image P2 is output to the display 2 and displayed. did. However, other monitors may be used as the display 2. Further, a projector or a printer may be used as the output device.

  For example, when a projector is used, the color chart P1 is projected onto the projection surface using the projector, the image of the projected color chart P1 is captured to obtain a captured color chart image, and the correction value calculation described above is performed. And a color conversion table may be generated. This makes it possible to generate a color conversion table that matches the output characteristics of the projector. When a printer is used, the color chart P1 printed using the printer is photographed to obtain a photographed color chart image, and the above-described correction value calculation and color conversion table generation are performed. . This makes it possible to generate a color conversion table that matches the output characteristics of the printer.

(2) In the above-described embodiment, as shown in FIG. 4, the frame 4a is displayed in the monitor 20, and the entire screen of the display 2 is taken within the frame 4a for the user. The dialog 4b in which a message for prompting is written is displayed. Then, an example will be described in which the user acquires an image so that the color chart P1 displayed on the display 2 has a predetermined size by photographing the entire screen of the display 2 within the frame 4a according to the description. did. However, the user may be prompted to have the color chart P1 displayed on the display 2 fall within the frame 4a.

  Note that the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired.

It is a figure which shows the example of a connection with the camera 1 display 2 typically. It is the figure which showed the switch for mode switching typically. 1 is a block diagram illustrating a configuration of an embodiment of a camera 1. FIG. It is a figure which shows the example of a screen display for encouraging imaging | photography of the display. It is a figure which shows the specific example of three endpoints described on the color chart. It is a figure which shows the specific example of a color conversion table. FIG. 6 is a flowchart showing processing of the camera 1. It is a flowchart figure which shows a correction value calculation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera, 11 Lens, 12 Image sensor, 13 Image controller, 14 System controller, 15 Memory controller, 161 Color chart image memory, 162 Image memory, 163 LUT, 17 Image recognizer, 18 Color error determiner, 19 Color corrector, 20 monitor, 2 display, 3 video output line, S1 switch mechanism

Claims (7)

Imaging means for capturing a subject image and acquiring the image;
Photographic image recording means for recording a photographic image acquired by the imaging means on a recording medium;
Reference image recording means for recording a reference image for measuring output characteristics of the output device on a recording medium;
A reference image output means for reading the reference image from the recording means and outputting it to the output device;
An image acquisition unit that captures an image of the reference image output to the output device with the imaging unit and acquires an image including the reference image;
Extraction means for extracting an extracted image corresponding to the reference image from the image including the reference image acquired by the image acquisition means;
Correction information calculation means for comparing the extracted image extracted by the extraction means with the reference image and calculating correction information for correcting the captured image output to the output device;
Correction means for correcting the captured image using the correction information;
An output control unit that outputs the captured image corrected by the correction unit to the output device. The camera of claim 1,
The image acquisition means urges a user to take an image including the reference image so that a size of the reference image in the image including the reference image becomes a predetermined size. . The camera according to claim 2,
A determination unit for determining a size of the reference image included in an image including the reference image acquired by the image acquisition unit;
The image acquisition means determines the size of the reference image to the user when the size of the reference image included in the image including the reference image is not the predetermined size by the determination means. A camera characterized by prompting re-shooting by outputting an explanation about the camera. The camera according to any one of claims 1 to 3,
The correction information recording means records a color conversion table in which color information before correction and color information after correction are associated with each other as the correction information on the recording medium. Record the captured image obtained by capturing the subject image on the recording medium,
A reference image for measuring the output characteristics of the output device is recorded on a recording medium,
Read the reference image and output to the output device,
Taking an image of the reference image output to the output device, obtaining an image including the reference image,
Extracting an extracted image in a range corresponding to the reference image from the image including the reference image,
Comparing the extracted image with the reference image to calculate correction information for correcting the captured image output to the output device;
An image correction value calculation method, wherein the correction information is recorded on a recording medium. The image correction value calculation method according to claim 5,
An image correction value calculation method, wherein the correction information recorded on the recording medium is read to correct the captured image. The image correction value calculation method according to claim 6,
An image correction value calculation method comprising outputting the corrected photographed image to the output device.

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