CMOS image sensor with analog gamma correction using nonlinear single-slope ADC

Author

Ham, Seogheon ; Lee, Yonghee ; Jung, Wunki ; Lim, Seunghyun ; Yoo, Kwisung ; Chae, Youngcheol ; Cho, Jihyun ; Lee, Dongmyung ; Han, Gunhee

Author_Institution

Syst. LSI Div., Samsung Electron. Corp., Kyungki

fYear

2006

fDate

21-24 May 2006

Lastpage

3581

Abstract

A human eye has the logarithmic response over wide range of light intensity. Although the gain can be set high to identify details in darker area on the image, this results in saturation in brighter area. The gamma correction is essential to fit the human eye. However, the digital gamma correction degrades image quality especially for darker area on the image due to the limited ADC resolution and the dynamic range. This paper proposes a CMOS image sensor (CIS) with nonlinear analog-to-digital converter (ADC) which performs analog gamma correction. The CIS with the proposed nonlinear ADC conversion scheme was fabricated with a 0.35-mum CMOS process. The test results show the improved image quality than digital gamma correction

Keywords

CMOS image sensors; analogue-digital conversion; image processing; 0.35 micron; CMOS image sensor; analog gamma correction; digital gamma correction; dynamic range; image quality; light intensity; logarithmic response; nonlinear analog-to-digital converter; nonlinear single-slope ADC; Analog-digital conversion; CMOS image sensors; CMOS process; Computational Intelligence Society; Degradation; Dynamic range; Humans; Image converters; Image quality; Image resolution;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2006. ISCAS 2006. Proceedings. 2006 IEEE International Symposium on

Conference_Location

Island of Kos

Print_ISBN

0-7803-9389-9

Type

conf

DOI

10.1109/ISCAS.2006.1693400

Filename

1693400