Method and apparatus for representing and searching for color images

• US 7,015,931 B1
• Filed: 04/28/2000
• Issued: 03/21/2006
• Est. Priority Date: 04/29/1999
• Status: Expired due to Term

• Current Assignee: Rakuten Group, Inc.
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Cieplinski, Leszek
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): CASCHERA, ANTONIO A
• Application Number:
  US09/959,409
• Time in Patent Office: 2,153 Days
• Field of Search: 382/168, 382/171, 345/593
• US Class Current: 345/619
• CPC Class Codes: G01J 3/463 Colour matching
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G06F 16/5838 using colour
• CPC Class Codes: G06F 16/5862 using texture
• CPC Class Codes: G06V 10/56 relating to colour
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A method of representing a color image comprises selecting a region of the image, selecting one or more colors as representative colors for the region and, for a region having two or more representative colors, calculating two parameters for each representative color including the variance of the color distribution of the image and the color space value and using these parameters to derive descriptors for the image region.

Claims

1. A method of representing a colour image comprising selecting two or more colours as dominant colours for an image and, for each dominant colour,

calculating variance of colour distribution of the image in colour space relative to the dominant colour, and

representing the image in terms of colour space value of each dominant colour and value of respective colour variance;

and

forming a descriptor including the colour space value of each dominant colour and the respective colour variance value.

2. A method as claimed in claim 1 wherein the said selecting includes deriving a colour histogram for a region of the image including the dominant colours.

3. A method as claimed in claim 2 wherein said selecting includes identifying local peaks in the colour histogram and selecting corresponding colours as dominant colours.

4. A method as claimed in claim 1 wherein said selecting includes selecting a region of the image, wherein the dominant colours are selected for the image region.

5. A method as claimed in claim 4 wherein said selecting the image region is independent of image content.

6. A method as claimed in claim 5 wherein said selecting includes selecting the image region which is a polygon.

7. A method as claimed in claim 4 wherein said selecting includes selecting the image region which corresponds to an object.

8. A method as claimed in claim 1 wherein said representing includes representing the image in terms of colour space value of each dominant colour, wherein the colour space value being expressed in terms of a plurality of colour components, and wherein said calculating includes calculating the colour variance for each colour component.

9. A method as claimed in claim 8 wherein said calculating includes calculating colour covariances for pairs of colour components.

10. An apparatus for implementing a method according to claim 1.

11. A computer system programmed to operate according to a method as claimed in claim 1.

12. A computer program for implementing a method as claimed in claim 1.

13. A computer-readable medium storing computer-executable process steps for implementing a method as claimed in claim 1.

14. A method as claimed in claim 1 wherein the descriptor additionally includes one or more elements indicating number of dominant colours, related covariance values, and weights indicating the relative significance of the dominant colour in the image region.

15. A method as claimed in claim 1 comprising storing said descriptor in a data storage means.