Method and apparatus for detecting image area, and computer product

• US 20060274339A1
• Filed: 12/30/2005
• Published: 12/07/2006
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Noda, Tsugio, Moroo, Jun
• Granted Patent: US 8,442,312 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32352 Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

An apparatus detects an area specified based on a mark of a specific color out of three primary colors in pigment or three primary colors in light from an image. An other-color-information eliminating unit eliminates information of other colors from a tone level of the specific color by correcting the tone level of the specific color based on tone levels of two colors other than the specific color out of the three primary colors in pigment or the three primary colors in light. An area detecting unit detects the area by specifying the mark based on the tone level from which the information of other colors is eliminated.

Claims

1. An apparatus that detects an area specified based on a mark of a specific color out of three primary colors in pigment or three primary colors in light from an image, the apparatus comprising:

an other-color-information eliminating unit that eliminates information of other colors from a tone level of the specific color by correcting the tone level of the specific color based on tone levels of two colors other than the specific color out of the three primary colors in pigment or the three primary colors in light; and

an area detecting unit that detects the area by specifying the mark based on the tone level from which the information of other colors is eliminated.

2. The apparatus according to claim 1, wherein

a minimum value of the tone level corresponds to a value of a tone level of a darkest color, and a maximum value of the tone level corresponds to a value of a tone level of a brightest color, and

the other-color-information eliminating unit eliminates information of other colors from a tone level of the specific color by adding a value obtained by subtracting a smaller value of a tone level out of tone levels of complementary colors of the two colors from the maximum value of the tone level, to a tone level of a complementary color of the specific color.

3. The apparatus according to claim 1, wherein

a minimum value of the tone level corresponds to a value of a tone level of a darkest color, and a maximum value of the tone level corresponds to a value of a tone level of a brightest color, and

the other-color-information eliminating unit eliminates information of other colors from a tone level of the specific color by adding a value obtained by subtracting a smaller value of a tone level out of tone levels of complementary colors of the two colors multiplied by a predetermined coefficient from the maximum value of the tone level, to a tone level of a complementary color of the specific color.

4. The apparatus according to claim 2, wherein

the specific color is yellow,

the complementary color of the specific color is blue, and

the complementary colors of the two colors are red and green.

5. The apparatus according to claim 3, wherein

the specific color is yellow,

the complementary color of the specific color is blue, and

the complementary colors of the two colors are red and green.

6. The apparatus according to claim 1, wherein

a minimum value of the tone level corresponds to a value of a tone level of a darkest color, and a maximum value of the tone level corresponds to a value of a tone level of a brightest color, and

the other-color-information eliminating unit eliminates information of other colors from the tone level of the specific color by subtracting a larger value of a tone level out of tone levels of the two colors from the tone level of the specific color.

7. The apparatus according to claim 1, wherein

a minimum value of the tone level corresponds to a value of a tone level of a darkest color, and a maximum value of the tone level corresponds to a value of a tone level of a brightest color, and

the other-color-information eliminating unit eliminates information of other colors from the tone level of the specific color by subtracting a value obtained by multiplying a larger value of a tone level out of tone levels of the two colors by a predetermined coefficient to from the tone level of the specific color.

8. The image-area detecting apparatus according to claim 6, wherein

the specific color is yellow, and

the two colors are cyan and magenta.

9. The image-area detecting apparatus according to claim 7, wherein

the specific color is yellow, and

the two colors are cyan and magenta.

10. The apparatus according to claim 1, wherein

a minimum value of the tone level corresponds to a value of a tone level of a darkest color, and a maximum value of the tone level corresponds to a value of a tone level of a brightest color, and

the other-color-information eliminating unit eliminates information of other colors from the tone level of the specific color by subtracting a larger value of a tone level out of tone levels of complementary colors of the two colors from a tone level of a complementary color of the specific color.

11. A method of detecting an area specified based on a mark of a specific color out of three primary colors in pigment or three primary colors in light from an image, the method comprising:

eliminating information of other colors from a tone level of the specific color by correcting the tone level of the specific color based on tone levels of two colors other than the specific color out of the three primary colors in pigment or the three primary colors in light; and

detecting the area by specifying the mark based on the tone level from which the information of other colors is eliminated.

12. A computer-readable recording medium that stores a computer program for detecting an area specified based on a mark of a specific color out of three primary colors in pigment or three primary colors in light from an image, wherein the computer program causes a computer to execute:

eliminating information of other colors from a tone level of the specific color by correcting the tone level of the specific color based on tone levels of two colors other than the specific color out of the three primary colors in pigment or the three primary colors in light; and

detecting the area by specifying the mark based on the tone level from which the information of other colors is eliminated.

13. A printed medium on which an image is printed, wherein

an area, which is specified based on a mark of a specific color out of three primary colors in pigment or three primary colors in light, is arranged in a detectable manner in the image,

the area can be detected by specifying the mark based on a tone level of the specific color from which information of other colors is eliminated by correcting the tone level of the specific color based on tone levels of two colors other than the specific color out of three primary colors in pigment or three primary colors in light,

an image data is divided into a plurality of blocks at a position related to the mark, and

a code is embedded in each pair of blocks based on a magnitude relation of a feature amount in each of the blocks.