Color Segmentation

• US 20080175481A1
• Filed: 01/18/2007
• Published: 07/24/2008
• Est. Priority Date: 01/18/2007
• Status: Active Grant

• Current Assignee: FotoNation Limited (Adeia Inc.)
• Original Assignee: DigitalOptics Corporation Europe Limited (Adeia Inc.)
• Inventors: Petrescu, Stefan, Gangea, Mihnea, Bigioi, Petronel, Pososin, Alexei, Drimbarean, Alex
• Granted Patent: US 8,055,067 B2
• Time in Patent Office: Days
• US Class Current: 382/190
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching

Abstract

A method of skin segmentation of a digital image is operable in an acquisition device. An image is acquired. A value indicative of a redness of a pixel of said image is compared with a face skin pixel redness criterion. The pixel is identified as a face skin pixel if said criteron is satisfied.

Claims

1. A method of skin segmentation of a digital image, said method operable in an image acquisition device, comprising:

acquiring an image;

comparing a value indicative of a redness of a pixel of said image with a face skin pixel redness criterion;

identifying said pixel as a face skin pixel if said criteron is satisfied.

2. A method as claimed in claim 1 wherein the redness criterion is proportional to the saturation of the pixel.

3. The method of claim 1 wherein said image is in RGB colour space, and wherein said value comprises the R value of said pixel.

4. The method of claim 3, wherein said criterion comprises R>

G+K and R>

B+K.

5. The method of claim 4 where K is a constant approximately equal to 15.

6. The method of claim 4 where K comprises approximately

x*(pixel saturation+y)

where x is in the range of approximately 0.53 to 0.6;

and

y is in the range of approximately 5 to 6.5.

7. The method of claim 6 comprising calculating said pixel saturation as:

Sqrt(R²*0.27847−

R*G*0.3061+G²*0.28503−

R*B*0.25005+B²*0.25661−

G*B*0.26317)

8. The method of claim 4 wherein said criterion further comprises an alternate condition that an intensity of said region, 1, is greater than 240.

9. The method of claim 1 wherein, when said image is in YCC colour space, and wherein said value is a Cr value of said pixel.

10. The method of claim 9 wherein said criterion comprises:

Cr>

148.8162−

0.1626*Cb+0.4726*K and

Cr>

1.2639*Cb−

33.7803+0.133*K

11. The method of claim 10 where K is a constant approximately equal to 15.

12. The method of claim 9 wherein said criterion comprises:

Cr>

148.8162−

0.1626*Cb+0.2836*(pixel saturation+5) and

Cr>

1.2639*Cb−

33.7803+0.4279*(pixel saturation+5)

where pixel saturation is;

√

{square root over (((Cr−

128)²+(Cb−

128)²))}{square root over (((Cr−

128)²+(Cb−

128)²))}

13. The method of claim 10 wherein said criterion further comprises an alternate condition that an intensity of said region, Y, is greater than 240.

14. The method of claim 1 further comprising partitioning said image into one or more regions of similar colors and wherein said value indicative of a redness of a pixel comprises an average pixel value for one of said one or more regions.

15. The method of claim 1 further comprising partitioning said image into one or more regions of pixels having been identified as face skin pixels.

16. The method of claim 1 wherein said comparing provides a real value and wherein said method comprises providing a contour map of a region comprising said real value.

17. The method of claim 16 further comprising analysing said contour map to locate one or more facial features within a region of face skin pixels.

18. The method of claim 16 further comprising analyzing said image to determine one or more candidate face regions and wherein said region that comprises said real value comprises one of said candidate face regions.

19. The method of claim 14 further comprising performing face detection on one or more regions of said image, each including a pixel having been identified as a face skin pixel.

20. The method of claim 15, further comprising performing face detection on one or more regions of said image, each including one of said one or more regions of face skin pixels.

21. A computer program product comprising computer program code which when executed on a computing device is arranged to perform the steps of claim 1.

22. A digital image processing device comprising a controller arranged to perform the steps of claim 1.