G-Channel Restoration for RWB CFA with Double-Exposed W Channel.
In this paper, we propose a green (G)-channel restoration for a red-white-blue (RWB) color filter array (CFA) image sensor using the dual sampling technique. By using white (W) pixels instead of G pixels, the RWB CFA provides high-sensitivity imaging and an improved signal-to-noise ratio compared to the Bayer CFA. However, owing to this high sensitivity, the W pixel values become rapidly over-saturated before the red-blue (RB) pixel values reach the appropriate levels. Because the missing G color information included in the W channel cannot be restored with a saturated W, multiple captures with dual sampling are necessary to solve this early W-pixel saturation problem. Each W pixel has a different exposure time when compared to those of the R and B pixels, because the W pixels are double-exposed. Therefore, a RWB-to-RGB color conversion method is required in order to restore the G color information, using a double-exposed W channel. The proposed G-channel restoration algorithm restores G color information from the W channel by considering the energy difference caused by the different exposure times. Using the proposed method, the RGB full-color image can be obtained while maintaining the high-sensitivity characteristic of the W pixels.
Yonsei University, Deptartment of Electrical and Electronic Engineering, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. ascaron5@gmail.com.
Chulhee
C
Park
Yonsei University, Deptartment of Electrical and Electronic Engineering, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. iamhoh@naver.com.
Ki Sun
KS
Song
Yonsei University, Deptartment of Electrical and Electronic Engineering, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. mkang@yonsei.ac.kr.
Moon Gi
MG
Kang
G-channel restoration; multispectral image sensor; red–white–blue color filter array