G-channel restoration for RWB CFA with double-exposed W channel

Chulhee Park, Ki Sun Song, Moon Gi Kang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article number293
JournalSensors (Switzerland)
Volume17
Issue number2
DOIs
Publication statusPublished - 2017 Feb 5

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restoration
Restoration
Color
Pixels
pixels
color
filters
sensitivity
sampling
Sampling
Signal-To-Noise Ratio
Image sensors
Signal to noise ratio
signal to noise ratios
saturation
Imaging techniques
sensors

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Biochemistry
  • Electrical and Electronic Engineering

Cite this

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title = "G-channel restoration for RWB CFA with double-exposed W channel",
abstract = "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.",
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G-channel restoration for RWB CFA with double-exposed W channel. / Park, Chulhee; Song, Ki Sun; Kang, Moon Gi.

In: Sensors (Switzerland), Vol. 17, No. 2, 293, 05.02.2017.

Research output: Contribution to journalArticle

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