Noise reduction in CMOS image sensors for high

Noise reduction in CMOS image sensors for high quality imaging: The autocorrelation function filter on burst image sequences Kazuhiro Hoshino 1, Frank Nielsen 2, 3, Toshihiro Nishimura 4 1 Image Sensor Business Group, Sony Corporation, 4 -14 -1 Asahi-chou, Atsugi-shi, Kanagawa, Japan Kazuhiro. Hoshino@jp. sony. com, 2 Sony Computer Science Laboratories, Inc. 3 -14 -13 Higashi Gotanda, Shinagawa-ku, Tokyo, Japan Frank. Nielsen@acm. org 3 Ecole Polytechnique, LIX F-91128 Palaiseau Cedex, France 4 Graduate School of Information, Production and Systems, Waseda University 2 -7 Hibikino, Wakamatsu, Kitakyushu, Fukuoka, Japan toshi-hiro@waseda. jp

Noise in image sensor Tx RST Image pixel Offset noise（C） Reset noise（W） 1/f noise(W ） P N N+ SEL Col. Bus V Decoder n (Condenser, CDS, Decoder) TG Programmable Gain Amp CMOS image sensor Dark noise（C） Dark shot noise（ W ） Photon shot noise（ W ） Condensing Gm（C） Amp noise（ W） Analog circuit Amp noise（ W ） Offset noise（C） Condensing Gm（C） 1/f noise（ W） W white noise, C colored noise.

Principle of an ACF n n The data is collected at the same interval time. Autocorrelation value is calculated according to the following equation. R is ACF value. N is the number of data, t is time. x is pixel value, and τ is shifted time.

1 D simulation of ACF (A) cosine wave (B) white noise wave Make base wave Block diagram of 1 -D ACF method ＋ Sampling In same interval time Calculation ACF value Make noise wave white noise wave Original wave ACF value (A) cosine wave (B) white noise wave

Expansion ACF method to 2 -D model V Tim e (a. u ) Time Ｉｍａｇｅ H H direction R is ACF value. N is the number of data which were sampled in time axis, t is time. x is pixel value, and τ is shifted time.

ACF value as a function of pixel intensity (A) Auto Correlation Value Pixel-Ａ (B) Pixel-B Flame Number Bright pixel A (180 in 256 scale) and dark pixel B (8 in 256 scale)

The algorithm of noise judging and filtering process by a time domain ACF method Image data (BMP, RAW) Pixel value extraction Pixel value i<10 No Calculation of ACF value r<0. 8 Leveling filter processing Pixel value decision I< Total pixel number No END No

Result of image processing ・ ・ Reduction of random noise is possible per pixel. Since filter processing is not performed in a bright pixel, resolution does not deteriorate. Original image Processing image

The algorithm and the example of processing of a time domain ACF method Image data (BMP, RAW) Pixel value extraction Pixel value i<10 No Calculation of ACF value r<0. 8 Leveling filter processing Pixel value decision I< Total pixel number No END No

Image processing result as a function of threshold value both pixel value and ACF value Original Ith= 100 Rth=0. 985 Ith= 100 Rth=0. 995 Rth=1. 000