IMAGE MATCHING APPARATUS, IMAGE MATCHING METHOD, COMPUTER PROGRAM AND COMPUTER-READABLE STORAGE MEDIUM

• US 20080219516A1
• Filed: 08/29/2007
• Published: 09/11/2008
• Est. Priority Date: 08/30/2006
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Suzuki, Takashi, Matsugu, Masakazu
• Granted Patent: US 7,995,805 B2
• Time in Patent Office: Days
• US Class Current: 382/118
• CPC Class Codes: G06V 40/161 Detection; Localisation; Normalisation

Abstract

An image matching apparatus comprising, a detector adapted to detects, from an input image containing an object to be matched, a region where the object exists, an estimation unit adapted to estimates a parameter regarding a displaying characteristic based on an image of the region, a correction unit adapted to corrects the displaying characteristic of the input image based on the parameter, and a matching unit adapted to matches the corrected input image containing the object to be matched with an image containing a matching object.

Claims

1. An image matching apparatus comprising:

a detector adapted to detects, from an input image containing an object to be matched, a region where the object exists;

an estimation unit adapted to estimates a parameter regarding a displaying characteristic based on an image of the region;

a correction unit adapted to corrects the displaying characteristic of the input image based on the parameter; and

a matching unit adapted to matches the corrected input image containing the object to be matched with an image containing a matching object.

2. The apparatus according to claim 1, further comprising:

a calculation unit adapted to calculates an area of a distribution of detection output related to the region; and

a determination unit adapted to determine whether the area falls within a predetermined range,

wherein said correction unit corrects the displaying characteristic of the input image when said determination unit determines that the area does not fall within the predetermined range.

3. The apparatus according to claim 1, wherein,

the object to be matched is a human face, and

said detection unit comprising:

a first detection unit adapted to detects a region where eyes and a mouth of the face are located; and

a second detection unit adapted to detects, based on the region where the eyes and the mouth are located, a region where the face is located.

4. The apparatus according to claim 1, wherein,

the displaying characteristic is a luminance value, and

said correction unit corrects the luminance value of the image by

changing a luminance value smaller than a first threshold value to a minimum luminance value,

changing a luminance value larger than a second threshold value to a maximum luminance value, and

linearly interpolating a luminance value located between the first threshold value and the second threshold value.

5. The apparatus according to claim 1, wherein said matching unit comprising:

an extraction unit adapted to extracts a specific region from the corrected input image

a vector generation unit adapted to generates a feature vector based on the displaying characteristic of the specific region; and

a vector matching unit adapted to executes matching by a support vector machine using the feature vector and the matching information registered in a registration unit.

6. The apparatus according to claim 5, wherein the specific region corresponds to eyes and a mouth when the object to be matched is a human.

7. An image matching method comprising:

detecting, from an input image containing an object to be matched, a region where the object exists;

estimating a parameter regarding a displaying characteristic based on an image of the region;

correcting the displaying characteristic of the input image based on the parameter; and

matching the corrected input image containing the object to be matched with an image containing a matching object.

8. The method according to claim 7, further comprising:

calculating an area of a distribution of detection output related to the region; and

determining whether the area falls within a predetermined range,

wherein the displaying characteristic of the input image is corrected when it is determined in the determining step that the area does not fall within the predetermined range.

9. The method according to claim 8, wherein

the object to be matched is a human face, and

said detecting the region comprising:

detecting a region where eyes and a mouth of the face are located; and

detecting, based on the region where the eyes and the mouth are located, a region where the face is located.

10. The method according to claim 8, wherein

the displaying characteristic is a luminance value, and

in correcting the luminance value, the luminance value of the image is corrected by

changing a luminance value smaller than a first threshold value to a minimum luminance value,

changing a luminance value larger than a second threshold value to a maximum luminance value, and

linearly interpolating a luminance value located between the first threshold value and the second threshold value.

11. The method according to claim 8, wherein said matching the corrected input image with the image containing the matching object comprising:

extracting a specific region from the corrected input image;

generating a feature vector based on a luminance value of the specific region; and

executing matching by a support vector machine using the feature vector and the matching information.

12. The method according to claim 11, wherein the specific region corresponds to eyes and a mouth when the object to be matched is a human.

13. A computer program stored in a storage medium to cause a computer to function as an image matching apparatus comprising:

a detector adapted to detects, from an input image containing an object to be matched, a region where the object exists;

an estimation unit adapted to estimates a parameter regarding a displaying characteristic based on an image of the region;

a correction unit adapted to corrects the displaying characteristic of the input image based on the parameter; and

a matching unit adapted to matches the corrected input image containing the object to be matched with an image containing a matching object.

14. A computer-readable storage medium which stores a computer program of claim 13.