Method and apparatus for detecting and processing specific pattern from image

• US 8,265,350 B2
• Filed: 12/06/2007
• Issued: 09/11/2012
• Est. Priority Date: 12/22/2006
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Torii, Kan, Matsugu, Masakazu, Mori, Katsuhiko, Sato, Hiroshi, Mitarai, Yusuke
• Primary Examiner(s): Carter, Aaron W
• Application Number:
  US11/951,809
• Publication Number:
  US 20080212879A1
• Time in Patent Office: 1,741 Days
• Field of Search: 382/118, 382/165, 382/195
• US Class Current: 382/118
• CPC Class Codes: G06V 30/287 of Kanji, Hiragana or Katakana characters
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body

Abstract

In an image within which a face pattern is detected, when a ratio of a skin color pixel is equal to or smaller than a first threshold value in a first region and a ratio of a skin color pixel is equal to or greater than a second threshold value in a second r region, the vicinity of the first region is determined to be a face candidate position at which the face pattern can exist. Face detection is carried out on the face candidate position. The second region is arranged in a predetermined position relative to the first region.

Claims

1. A method comprising:

determining a ratio of pixels having a first attribute in a first region of an image to generate a first determination result;

determining a ratio of pixels having a second attribute in a second region of the image to generate a second determination result, wherein the second region is arranged inside the first region, and the first and second regions are rotationally symmetric figures having coincident centers;

determining whether human face images can exist in the vicinity of the first region based on the first determination result and the second determination result; and

detecting a human face image in the vicinity of the first region when it is determined that the human face image can exist.

2. The method according to claim 1, wherein the first determination result is generated based on whether a ratio of pixels having the first attribute is within a first range.

3. The method according to claim 2, wherein the second determination result is generated based on whether a ratio of pixels having the second attribute is within a second range.

4. The method according to claim 1, wherein the first region is a first rectangular region, and wherein the second region is included in the first rectangular region and is a second rectangular region having sides parallel to the first rectangular region.

5. The method according to claim 1, wherein attributes of the pixels are pixel chromaticity, luminance, hue, chroma saturation, or brightness.

6. The method according to claim 1, further comprising generating cumulative images of the image, wherein, in the first and second ratio determination, a ratio of pixels is determined by using the cumulative images.

7. The method according to claim 1, wherein the first attribute and the second attribute are associated with a skin color and the human face image.

8. A method comprising:

determining a ratio of pixels having a predetermined attribute within each figure with respect to one or more figures that include a rotationally symmetric figure in an image;

determining whether human face images can exist in the vicinity of the figure, based on a result of the ratio determination; and

detecting a human face image and an image obtained by rotating the human face image in a portion of the image where it is determined that the human face image can exist.

9. The method according to claim 8, wherein, in the ratio determination, it is determined whether a ratio of pixels having the attribute is within a predetermined range.

10. The method according to claim 8, wherein said one or more figures are two or more figures that are arranged in predetermined relative positions.

11. The method according to claim 8, wherein said one or more figures are two or more rotationally symmetric figures having coincident centers.

12. The method according to claim 8, wherein attributes of the pixels are pixel chromaticity, luminance, hue, chroma saturation, or brightness.

13. The method according to claim 8, further comprising generating cumulative images of the image, wherein a ratio of pixels is determined by using the cumulative images.

14. An apparatus comprising:

a first ratio determination unit configured to determine a ratio of pixels having a first attribute in a first region of an image;

a second ratio determination unit configured to determine a ratio of pixels having a second attribute in a second region of the image that is arranged inside the first region, and the first and second regions are rotationally symmetric figures having coincident centers;

a determination unit configured to determine whether human face images can exist in the vicinity of the first region based on determination results of the first and second ratio determination units; and

a detection unit configured to detect a human face image in the vicinity of the first region when it is determined that the human face image can exist.

15. The apparatus according to claim 14, wherein the first ratio determination unit is configured to determine a ratio of pixels having a skin color attribute in the first region of the image, and the second ratio determination unit is configured to determine a ratio of pixels having the skin color attribute in the second region of the image;

and

wherein the determination unit, when the ratio of pixels having the skin color attribute in the first region is smaller than a first threshold value and the ratio of pixels having the skin color attribute in the second region is greater than a second threshold value, determines whether a face pattern can exist in a vicinity of the first region.

16. The apparatus according to claim 15, wherein the determination unit performs a face detection in the vicinity of the first region when it is determined by the determination unit that a face pattern can exist in a vicinity of the first region.

17. An apparatus comprising:

a ratio determination unit configured to determine a ratio of pixels having a predetermined attribute within each figure with respect to one or more figures that include a rotationally symmetric figure in an image;

a determination unit configured to determine whether human face images can exist in the vicinity of the figure based on a result of the ratio determination; and

a detection unit configured to detect a human face image and an image obtained by rotating the human face image in a portion of the image where it is determined that the human face image can exist.