A complementary metal-oxide-semiconductor image sensor with analog gamma correction using a nonlinear single-slope analog-to-digital converter

Seogheon Ham, Wunki Jung, Seunghyun Lim, Yonghee Lee, Gunhee Han

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

An image sensor has limited dynamic range while the human eye has a logarithmic response over a wide range of light intensity. Although the sensor gain can be set high to identify details in darker areas on an image, this high gain results in saturation in brighter areas. Therefore, gamma correction is essential to match the human eye response. However, the digital gamma correction degrades image quality, especially for darker areas on the image, due to the limited resolution and dynamic range of the analog-to-digital converter (ADC). In this paper, we propose a complementary metal-oxide-semiconductor (CMOS) image sensor (CIS) with a compact nonlinear ADC which performs analog gamma corrections that use the full dynamic range. A CIS with the proposed nonlinear ADC was fabricated with a 0.35-μm CMOS process. The test results show that the analog gamma correction provides a 2. 2dB peak-signal-to-noise-ratio (PSNR) improved image quality, which is better than conventional digital gamma corrections.

Original languageEnglish
Pages (from-to)2522-2524
Number of pages3
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume45
Issue number4 A
DOIs
Publication statusPublished - 2006 Apr 7

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analog to digital converters
Digital to analog conversion
Image sensors
CMOS
analogs
slopes
Image quality
sensors
Metals
dynamic range
Signal to noise ratio
Sensors
Oxide semiconductors
high gain
luminous intensity
signal to noise ratios
saturation

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

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AU - Han, Gunhee

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