Image processing method and apparatus for processing an image by using a face detection result

Abstract

An image processing apparatus determines, when white balance correction is executed on an image signal of a face area detected by face detection unit, based on a first white balance correction value obtained by detecting white pixels, whether the corrected image signal of the face area is present in a second color signal area around a first color signal area indicating a flesh color. When the corrected image signal of the face area is determined to be present in the second color signal area, the image processing apparatus calculates a second white balance correction value for correcting the image signal based on a relationship between the corrected image signal of the face area and the first color signal area.

What is claimed is: 
     
       1. An image processing apparatus for processing an image signal of an image obtained by capturing, the image processing apparatus comprising:
 a first calculation unit configured to calculate a first white balance correction value by detecting white pixels from the image; 
 a face detection unit configured to detect a face area from the image; 
 a determination unit configured to determine, after white balance correction based on the first white balance correction value is executed on an image signal of the face area detected by the face detection unit, whether the corrected image signal of the face area is present in a second color signal area around a first color signal area indicating a flesh color; and 
 a second calculation unit configured to calculate, when the determination unit determines that the corrected image signal of the face area is present in the second color signal area, a second white balance correction value for correcting the image signal based on a relationship between the corrected image signal of the face area and the first color signal area; and 
 a white balance correction unit configured to correct white balance of the image, 
 wherein the white balance correction unit executes white balance correction selectively by using the second white balance correction value when the determination unit determines that the corrected image signal of the face area is present in the second color signal area, and by using the first white balance correction value when the determination unit determines that the corrected image signal of the face area is not present in the second color signal area. 
 
     
     
       2. The image processing apparatus according to  claim 1 , further comprising a white balance correction unit configured to correct white balance of the image,
 wherein the white balance correction unit executes white balance correction selectively by using the second white balance correction value when the determination unit determines that the corrected image signal of the face area is present in the second color signal area, and by using the first white balance correction value when the determination unit determines that the corrected image signal of the face area is not present in the second color signal area.   
     
     
       3. The image processing apparatus according to  claim 1 , wherein the second calculation unit corrects the image signal so that the image signal of the face area is located in the first color signal correction area. 
     
     
       4. The image processing apparatus according to  claim 1 , wherein the first calculation unit detects the white pixels of the image for each predetermined block wherein the image is divided into blocks, and the determination unit executes the determination on the image signal of the face area for each predetermined block. 
     
     
       5. An image processing apparatus for processing an image signal of an image obtained by capturing, the image processing apparatus comprising:
 a white balance correction unit configured to correct white balance of the image signal; 
 a face detection unit configured to detect a face area from the image; 
 a first calculation unit configured to calculate a first white balance correction value used for the white balance correction based on an image signal of a block which is present in a color signal area indicating white from among blocks into which the image is divided and each of which includes a plurality of pixels; and 
 a second calculation unit configured to add corrected image signals present in a first color signal area indicating a flesh color and a second color signal area that is a surrounding area of the first color signal area from among corrected image signals obtained after correcting white balance of image signals of blocks included in the face area based on the first white balance correction value when the face detection unit detects the face area, and to calculate a second white balance correction value for correcting a total of image signals to enter the first color signal area when the total of image signals obtained by the addition is present in the second color signal area, 
 wherein the white balance correction unit executes white balance correction by using the second white balance correction value when the second white balance correction value is calculated. 
 
     
     
       6. The image processing apparatus according to  claim 5 , wherein the second calculation unit adds the corrected image signals included in neither of the first and second color signal areas, and adds the corrected image signals included in the first color signal area, the corrected image signals included in the second color signal area, and the corrected image signals included in neither of the first and second color signal areas after applying different weights to the respective corrected image signals, and
 wherein the weights applied to the corrected image signals included in neither of the first and second color signal areas are lower than the weights applied to the corrected image signals included in the first and second color signal areas. 
 
     
     
       7. The image processing apparatus according to  claim 5 , wherein, when no second white balance correction value is calculated, the white balance correction unit executes white balance correction by using the first white balance correction value. 
     
     
       8. The image processing apparatus according to  claim 5 , wherein the first and second calculation units calculate the first and second white balance correction values by using image signals of images obtained by capturing after the image processed by the face detection unit. 
     
     
       9. An imaging apparatus comprising:
 an imaging unit configured to output an image signal of an image obtained by capturing; and 
 the image processing apparatus according to  claim 5 . 
 
     
     
       10. A method for processing an image signal of an image obtained by capturing, the method comprising:
 calculating, using a processor, a first white balance correction value by detecting a white pixel from the image; 
 detecting a face area from the image; 
 determining whether the corrected image signal of the face area is present in a second color signal area around a first color signal area indicating a flesh color after white balance correction is executed on an image signal of the detected face area based on the first white balance correction value; and 
 calculating, using a processor, a second white balance correction value for correcting the image signal when the corrected image signal of the face area is determined to be present in the second color signal area based on a relationship between the corrected image signal of the face area and the first color signal area; and 
 executing white balance correction selectively by using the second white balance correction value when it is determined that the corrected image signal of the face area is present in the second color signal area, and by using the first white balance correction value when it is determined that the corrected image signal of the face area is not present in the second color signal area. 
 
     
     
       11. A method for processing an image signal of an image obtained by capturing, the method comprising:
 detecting a face area from the image; 
 calculating, using a processor, a first white balance value used for white balance correction based on an image signal of a block present in a color signal area indicating white from among blocks into which the image is divided for a plurality of pixels; 
 adding, when the face area is detected, corrected image signals present in a first color signal area indicating a flesh color and a second color signal area that is a surrounding area of the first color signal area from among corrected image signals obtained after correcting white balance of image signals of blocks included in the face area based on the first white balance correction value, and calculating, using a processor, a second white balance correction value when a total of image signals obtained by the addition is present in the second color signal area for correcting the total of image signals to enter the first color signal area; 
 executing white balance correction for the image signal by using the first and second white balance correction values; and 
 executing, when the second white balance correction value is calculated, white balance correction by using the second white balance correction value. 
 
     
     
       12. An image processing apparatus for processing an image signal of an image obtained by capturing, the image processing apparatus comprising:
 a first calculation unit configured to calculate a first white balance correction value based on the image;   a face detection unit configured to detect a face area from the image;   a determination unit configured to determine, in a case where white balance correction based on the first white balance correction value is executed on an image signal of a face area, whether the corrected image signal of the face area is present in a second color signal area different from a first color signal area indicating a flesh color;   a second calculation unit configured to calculate, in a case where the determination unit determines that the corrected image signal of the face area is present in the second color signal area, a second white balance correction value for correcting the image signal based on a relationship between the corrected image signal of the face area and the first color signal area; and   a white balance correction unit configured to correct white balance of the image using the first white balance correction value and the second white balance correction value.   
     
     
       13. The image processing apparatus according to claim 12, wherein the first calculation unit calculates the first white balance correction value by detecting white pixels from the image. 
     
     
       14. The image processing apparatus according to claim 12, wherein the second color signal area is around a first color signal area. 
     
     
       15. The image processing apparatus according to claim 12, wherein the white balance correction unit executes white balance correction selectively by using the second white balance correction value in a case where the determination unit determines that the corrected image signal of the face area is present in the second color signal area, and by using the first white balance correction value in a case where the determination unit determines that the corrected image signal of the face area is not present in the second color signal area. 
     
     
       16. The image processing apparatus according to claim 12, wherein the second calculation unit corrects the image signal so that the image signal of the face area is located in the first color signal area. 
     
     
       17. The image processing apparatus according to claim 12, wherein the image is divided into blocks, and the determination unit executes the determination on the image signal of the face area for each block. 
     
     
       18. A method for processing an image signal of an image obtained by capturing, the method comprising:
 calculating, using a processor, a first white balance correction value;   detecting a face area from the image;   determining, in a case where white balance correction is executed on an image signal of a face area based on the first white balance correction value, whether the corrected image signal of the face area is present in a second color signal area different from a first color signal area indicating a flesh color;   calculating, using a processor, a second white balance correction value for correcting the image signal in a case where the corrected image signal of the face area is determined to be present in the second color signal area based on a relationship between the corrected image signal of the face area and the first color signal area; and   correcting white balance of the image using the first white balance correction value and the second white balance correction value.   
     
     
       19. A non-transitory computer-readable storage medium storing a control program for implementing a control method of controlling an image processing apparatus for processing an image signal of an image obtained by capturing, the control method comprising:
 calculating, using a processor, a first white balance correction value by detecting a white pixel from the image;   detecting a face area from the image based on the image;   determining, in a case where white balance correction is executed on an image signal of the detected face area based on the first white balance correction value, whether the corrected image signal of the face area is present in a second color signal area around a first color signal area indicating a flesh color;   calculating, using a processor, a second white balance correction value for correcting the image signal in a case where the corrected image signal of the face area is determined to be present in the second color signal area based on a relationship between the corrected image signal of the face area and the first color signal area; and   correcting white balance of the image using the first white balance correction value and the second white balance correction value.   
     
     
       20. A non-transitory computer-readable storage medium storing a control program for implementing a control method of controlling an image processing apparatus for processing an image signal of an image obtained by capturing, the control method comprising:
 detecting a face area from the image;   calculating, using a processor, a first white balance value used for white balance correction based on an image signal of a block present in a color signal area indicating white among blocks into which the image is divided for a plurality of pixels;   adding, in a case where the face area is detected, corrected image signals present in a first color signal area indicating a flesh color and a second color signal area that is a surrounding area of the first color signal area among corrected image signals obtained after correcting white balance of image signals of blocks included in the face area based on the first white balance correction value, and calculating, using a processor, a second white balance correction value in a case where a total of image signals obtained by the addition is present in the second color signal area for correcting the total of image signals to enter the first color signal area;   executing white balance correction for the image signal by using the first and second white balance correction values; and   executing, in a case where the second white balance correction value is calculated, white balance correction by using the second white balance correction value.   
     
     
       21. A non-transitory computer-readable storage medium storing a control program for implementing a control method of controlling an image processing apparatus for processing an image signal of an image obtained by capturing, the control method comprising:
 calculating, using a processor, a first white balance correction value;   detecting a face area from the image;   determining, in a case where white balance correction is executed on an image signal of a face area based on the first white balance correction value, whether the corrected image signal of the face area is present in a second color signal area different from a first color signal area indicating a flesh color;   calculating, using a processor, a second white balance correction value for correcting the image signal in a case where the corrected image signal of the face area is determined to be present in the second color signal area based on a relationship between the corrected image signal of the face area and the first color signal area; and   correcting white balance of the image using the first white balance correction value and the second white balance correction value.