1. Effective Color Interpolation in CCD Color Filter Arrays Using Signal Correlation
作者:Soo-Chang Pei, Io-Kuong Tam
出處: IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 13, NO. 6, JUNE 2003
報告人:董文豪
日期:2011/05/04

2. Outline Introduction Color Filter Arrays ( CFA )
Conventional interpolation methods
Bilinear
Edge-sensing interpolation
Proposed interpolation method
Experiment results

3. Introduction
The authors propose an effective color filter array (CFA) interpolation method for digital still cameras using a simple image model that correlates the R,G,B channels.
A low-complexity interpolation method to improve the image quality.

4. Color Filter Arrays -CFA ( 1/2 )
Three-CCD structure for a DSC.
Single-CCD structure for a DSC.

5. Color Filter Arrays -CFA ( 1/2 )

6. Conventional interpolation methods ( 1/4 )
Bilinear
G3+G6+G8+G11 4
G’7= R1 B2 G3 B4
R1+R7 2
R’3= R5 G6 R7 G8 R9
B10
G11
B12
B2+B4+B10+B12 4
B’7=
R13

7. Conventional interpolation methods ( 2/4 )
Bilinear H H L L H H L L H H L L H H L L
Vertical edge patterns
An obvious error is produced and the edge pattern is destroyed.

8. Conventional interpolation methods ( 3/4 )
Edge-sensing interpolation ( G ) R1 B2 G3 B4 R5 G6 R7 G8 R9
B10
G11
B12
R13 R1
G6 + G8 2
G’7H=
∆H=|G6 - G8| , ∆V=|G3 – G11|,
If ( ∆H < T ) and ( ∆V > T ) ,
G’7 = G’7H ,
else if ( ∆V < T ) and ( ∆H > T ) ,
G’7 = G’7V
else
G’7 = G’7A B2 G3 B4
G3 + G11 2
G’7V= R5 G6 R7 G8 R9
B10
G11
B12
G3 + G6 + G8 + G11 4
G’7A=
R13

9. Conventional interpolation methods ( 4/4 )
Edge-sensing interpolation ( R,B ) G3 G6 G8
G11 R1 B G R G
HB =
, HR = B2 G3 B4
B 2
G’2
B 4
G’4 G3 2
B’3 =
( ) /2
( ) R5 G6 R7 G8 R9
B 2
G’2
B 4
G’4
B10
G’10
B 12
G’12
G’7 4
B10
G11
B12
B’7 =
( ) /4
( )
R13

10. Proposed interpolation method ( 1/3 )
Above two methods use only the existing G channel neighborhood information to find the missing G values.
There is a high correlation between the R,G,B channels.
The G channel can take advantage of the R and B information.

11. Proposed interpolation method ( 2/3 )
G channel image
KR channel image
KB channel image
KR = G – R
KB = G – B

12. Proposed interpolation method ( 3/3 )
R,B Channel Interpolation
G Channel Interpolation R1
G’7 = R7
+( K’R3 + K’R6 + K’R8 + K’R11 ) /4 1 4 1 2
= R ［G3 - (R7+R1) +
G (R7+R5) +
G (R7+R9) +
G11- (R7+R13)］ 1 2
R’3 =
G3 - ( K’R1 + K’R7 ) B2 G3 B4 1 2 R5 G6 R7 G8 R9 1 2 1 4
B’7=
G’7- ( K’B2+ K’B4+ K’B10+ K’B12 ) 1 2
B10
G11
B12 1 2 1 4
= R7+ ( G3+G6+G8+G11 )
- ( R1+R5+R9+R13 )
R13 1 8
KR = G – R
KB = G – B

13. Experiment results ( 1/2 )
PSNR OF THE INTERPOLATED RESULTS

14. Experiment results ( 2/2 )
COMPLEXITY COMPARISON 1 2 1 4
G’7 = R7+ ( G3+G6+G8+G11 )
- ( R1+R5+R9+R13 ) 1 8

15. The end