Image processing apparatus and image processing method

• US 8,614,751 B2
• Filed: 05/01/2012
• Issued: 12/24/2013
• Est. Priority Date: 05/06/2011
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ogawa, Shigeo
• Primary Examiner(s): CHEN, CHIA WEI A
• Application Number:
  US13/461,528
• Publication Number:
  US 20120281110A1
• Time in Patent Office: 602 Days
• Field of Search: 348/222.1, 348/223.1, 348/224.1, 348/225.1, 348/370, 348/371, 348655-658, 382/107
• US Class Current: 348/224.1
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

An image processing apparatus calculates a difference in color temperature between a first white balance (WB) correction value based on image data with flash and a second WB correction value based on image data without flash. The image forming apparatus calculates motion amounts of an object and the apparatus, and corrects the first and second WB correction values based on the difference in color temperature and the motion amounts. The image processing apparatus, based on the corrected first WB correction value, develops first image data from the image data with flash, and, based on the corrected second WB correction value, develops second image data from the image data without flash. The image processing apparatus calculates a signal component of external light and a signal component of flash and calculates a combination ratio of the first and second image data to combine the first and second image data.

Claims

1. An image processing apparatus comprising:

a correction value calculation unit configured to calculate a first white balance correction value based on image data captured with flash and to calculate a second white balance correction value based on image data captured without flash;

a difference calculation unit configured to calculate a difference in color temperature between the first white balance correction value and the second white balance correction value;

a motion amount calculation unit configured to calculate a motion amount of at least one of an object and the image processing apparatus;

a correction unit configured to correct the first white balance correction value and the second white balance correction value based on at least one of the difference in color temperature and the motion amount;

a development unit configured to develop first image data from the image data captured with flash based on the first white balance correction value corrected by the correction unit and to develop second image data from the image data captured without flash based on the second white balance correction value corrected by the correction unit;

a component calculation unit configured to calculate a luminance component of external light and a luminance component of flash based on a luminance value of the image data captured without flash and a luminance value of the image data captured with flash;

a combination ratio calculation unit configured to calculate a combination ratio of the first image data and the second image data based on the luminance component of external light and the luminance component of flash; and

a combination unit configured to combine the first image data with the second image data according to the combination ratio.

2. The image processing apparatus according to claim 1, wherein the combination ratio calculation unit is configured to calculate the combination ratio of the first image data and the second image data for each block based on the luminance component of external light and the luminance component of flash in each block.

3. The image processing apparatus according to claim 2, wherein the combination ratio calculation unit is configured to calculate the combination ratio for each pixel based on the combination ratio for each block by pixel interpolation processing.

4. The image processing apparatus according to claim 1, wherein the combination unit is configured to control whether to perform combining processing on applicable blocks according to a luminance value of each block.

5. The image processing apparatus according to claim 1, wherein the correction value calculation unit is configured to calculate the second white balance correction value to leave arbitrary tint for a light source.

6. The image processing apparatus according to claim 1, wherein the motion amount calculation unit is configured to calculate the motion amount of at least one of the image processing apparatus and the object based on at least one of a detection result of a motion of the image processing apparatus by an inertial sensor and an analysis result of a motion of the object based on the image data captured with flash and the image data captured without flash.

7. The image processing apparatus according to claim 1, wherein the correction unit is configured to correct the first white balance correction value and the second white balance correction value to become closer to each other, or to correct, while fixing one of the first white balance correction value and the second white balance correction value, the other of the first white balance correction value and the second white balance correction value to become closer to the one of the first white balance correction value and the second white balance correction value.

8. An image processing method comprising:

calculating a first white balance correction value based on image data captured with flash and calculating a second white balance correction value based on image data captured without flash;

calculating a difference in color temperature between the first white balance correction value and the second white balance correction value;

calculating a motion amount of at least one of an object and an image processing apparatus;

correcting the first white balance correction value and the second white balance correction value based on at least one of the difference in color temperature and the motion amount;

developing first image data from the image data captured with flash based on the corrected first white balance correction value and developing second image data from the image data captured without flash based on the corrected second white balance correction value;

calculating a luminance component of external light and a luminance component of flash based on a luminance value of the image data captured without flash and a luminance value of the image data captured with flash;

calculating a combination ratio of the first image data and the second image data based on the luminance component of external light and the luminance component of flash; and

combining the first image data with the second image data according to the combination ratio.

9. A non-transitory computer-readable medium storing a program causing a computer to execute a method comprising:

calculating a first white balance correction value based on image data captured with flash and calculating a second white balance correction value based on image data captured without flash;

calculating a difference in color temperature between the first white balance correction value and the second white balance correction value;

calculating a motion amount of at least one of an object and an image processing apparatus;

correcting the first white balance correction value and the second white balance correction value based on at least one of the difference in color temperature and the motion amount;

developing first image data from the image data captured with flash based on the corrected first white balance correction value and developing second image data from the image data captured without flash based on the corrected second white balance correction value;

calculating a luminance component of external light and a luminance component of flash based on a luminance value of the image data captured without flash and a luminance value of the image data captured with flash;

calculating a combination ratio of the first image data and the second image data based on the luminance component of external light and the luminance component of flash; and

combining the first image data with the second image data according to the combination ratio.