System and method for performing region-based image retrieval using color-based segmentation

• US 20030215135A1
• Filed: 05/09/2003
• Published: 11/20/2003
• Est. Priority Date: 08/17/1999
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Challapali, Kiran, Caron, Cedric Y., Yan, Yong
• Application Number:
  US10/434,595
• Publication Number:
  US 20030215135A1
• Time in Patent Office: Days
• US Class Current: 382/173
• CPC Class Codes: G06F 16/5838 using colour
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 10/267 by performing operations on regions, e.g. growing, shrinking or watersheds
• CPC Class Codes: G06V 10/56 relating to colour

Abstract

An image retrieval system is provided for analyzing an image in a first color model format and detecting and retrieving from the image a selected image portion. The image retrieval system comprises an image processor for converting pixels in the image from the first color model format to a (Yrθ) color model format, where Y is an intensity component indicating a total amount of light, r is a saturation component indicating an amount of white light mixed with a color of each pixel, and θ is a hue component indicating the color of each pixel. The image processor groups spatially adjacent pixels into image regions according to hue components of the adjacent pixels and performs a merging process wherein a first image region and an adjacent second image region are merged into a composite region if a hue difference between the first and second image regions is less than a predetermined hue difference threshold. The process is repeated to continually merge regions of similar hue until no further merges can be performed.

Claims

1. An image processing device, comprising:

an image processor that is configured to;

convert a plurality of pixels of an image from a first color model format to a (Y,r,θ

) color model format, wherein;

Y is an intensity component indicating a total amount of light,

r is a saturation component indicating an amount of white light mixed with a color of the each pixel, and

θ

is a hue component indicating the color of the each pixel;

group spatially adjacent ones of the plurality of pixels into a plurality of image regions according to hue components of the adjacent pixels, substantially independent of intensity components and the saturation components of the adjacent pixels; and

selectively merge a first image region and a second image region proximate the first image region into a composite region if a hue difference between the first and second image regions is less than a predetermined hue difference threshold.

2. The image processing device of claim 1, wherein

the image processor is configured to determine a histogram of hue components of the pixels in the image,

the histogram indicating a number of pixels of similar hue in the image.

3. The image processing device of claim 2, wherein

the image processor is configured to determine a dominant hue in the image using a peak detection algorithm on the histogram.

4. The image processing device of claim 1, wherein

the image processor is configured to determine and to mark ones of the plurality of image regions having less than a predetermined minimum number of pixels and disregarding the marked image regions during the merging process.

5. The image processing device of claim 1, wherein

the image processor is configured to determine and mark achromatic ones of the plurality of image regions having less than a predetermined minimum number of pixels and disregarding the marked achromatic image regions during the merging process.

6. The image processing device of claim 5, wherein

the first and second image regions are merged if a number of pixels in the first image region and a number of pixels in the second image region are greater than a predetermined image region size threshold.

7. An image retrieval system capable of analyzing an image comprising a plurality of pixels in a first color model format comprising:

an image processing device capable of detecting and retrieving from the image a selected image portion,

the image processing device comprising;

an image processor that is configured to;

convert the plurality of pixels in the image from the first color model format to a (Y,r,θ

) color model format,

wherein

for each pixel in the plurality of pixels,

Y is an intensity component indicating a total amount of light,

r is a saturation component indicating an amount of white light mixed with a color of the each pixel, and

θ

is a hue component indicating the color of the each pixel;

group spatially adjacent ones of the plurality of pixels into a plurality of image regions according to hue components of the adjacent pixels, substantially independent of intensity components and the saturation components of the adjacent pixels; and

perform a merging process to merge a first image region and a second image region proximate the first image region into a composite region, if a hue difference between the first and second image regions is less than a predetermined hue difference threshold;

a display monitor that is configured to display the composite region; and

a user input device that is configured to receive user commands capable of controlling the merging process.

8. The image retrieval system of claim 7, wherein

the image processor is configured to determine a histogram of hue components of the pixels in the image,

the histogram indicating a number of pixels of similar hue in the image.

9. The image retrieval system of claim 8, wherein

the image processor is configured to determine a dominant hue in the image based on the histogram.

10. The image retrieval system of claim 9, wherein

the image processor is configured to:

determine and mark ones of the plurality of image regions having less than a predetermined minimum number of pixels, and

disregard the marked image regions during the merging process.

11. The image retrieval system of claim 7, wherein

the image processor is configured to:

determine and mark achromatic ones of the plurality of image regions having less than a predetermined minimum number of pixels, and

disregard the marked achromatic image regions during the merging process.

12. The image retrieval system of claim 11, wherein

the first and second image regions are merged if a number of pixels in the first image region and a number of pixels in the second image region are greater than a predetermined image region size threshold.

13. A method of processing an image comprising a plurality of pixels in a first color model format, the method comprising:

converting the plurality of pixels in the image from the first color model format to a (Y,r,θ

) color model format,

wherein for each pixel in the plurality of pixels,

Y is an intensity component indicating a total amount of light,

r is a saturation component indicating an amount of white light mixed with a color of each pixel, and

θ

is a hue component indicating the color of each pixel; and

grouping spatially adjacent ones of the plurality of pixels into a plurality of image regions according to hue components of the adjacent pixels, substantially independent of intensity components and the saturation components of the adjacent pixels; and

performing a merging process,

wherein a first image region and a second image region proximate the first image region are merged into a composite region if a hue difference between the first and second image regions is less than a predetermined hue difference threshold.

14. The method of claim 13, further comprising:

determining and marking ones of the plurality of image regions having less than a predetermined minimum number of pixels; and

disregarding the marked image regions during the merging process.

15. The method of claim 13, further comprising:

determining and marking achromatic ones of the plurality of image regions having less than a predetermined minimum number of pixels; and

disregarding the marked achromatic image regions during the merging process.

16. The method of claim 13, wherein

the first and second image regions are merged if a number of pixels in the first image region and a number of pixels in the second image region are greater than a predetermined image region size threshold.

17. For use in an image retrieval system capable of analyzing an image comprising a plurality of pixels in a first color model format, a computer executable process, stored on a computer readable storage medium, for detecting and retrieving from the image a selected image portion comprising:

converting the plurality of pixels in the image from the first color model format to a (Y,r,θ

) color model format,

wherein for each pixel in the plurality of pixels,

Y is an intensity component indicating a total amount of light,

r is a saturation component indicating an amount of white light mixed with a color of each pixel, and

θ

is a hue component indicating the color of each pixel; and

grouping spatially adjacent ones of the plurality of pixels into a plurality of image regions according to hue components of the adjacent pixels, substantially independent of intensity components and the saturation components of the adjacent pixels; and

performing a merging process,

wherein a first image region and a second image region proximate the first image region are merged into a composite region if a hue difference between the first and second image regions is less than a predetermined hue difference threshold.

18. The computer executable process of claim 17, further comprising:

determining and marking ones of the plurality of image regions having less than a predetermined minimum number of pixels; and

disregarding the marked image regions during the merging process.

19. The computer executable process of claim 17, further comprising:

determining and marking achromatic ones of the plurality of image regions having less than a predetermined minimum number of pixels; and

disregarding the marked achromatic image regions during the merging process.

20. The computer executable process of claim 17, wherein

the first and second image regions are merged if a number of pixels in the first image region and a number of pixels in the second image region are greater than a predetermined image region size threshold.