A digital ISO expansion technique for digital cameras

Youngjin Yoo; Kangeui Lee; Wonhee Choe; SungChan Park; Seong-Deok Lee; Chang-Yong Kim

doi:10.1117/12.838774

18 January 2010 A digital ISO expansion technique for digital cameras

Youngjin Yoo, Kangeui Lee, Wonhee Choe, SungChan Park, Seong-Deok Lee, Chang-Yong Kim

Proceedings Volume 7537, Digital Photography VI; 75370U (2010) https://doi.org/10.1117/12.838774
Event: IS&T/SPIE Electronic Imaging, 2010, San Jose, California, United States

Abstract

Market's demands of digital cameras for higher sensitivity capability under low-light conditions are remarkably increasing nowadays. The digital camera market is now a tough race for providing higher ISO capability. In this paper, we explore an approach for increasing maximum ISO capability of digital cameras without changing any structure of an image sensor or CFA. Our method is directly applied to the raw Bayer pattern CFA image to avoid non-linearity characteristics and noise amplification which are usually deteriorated after ISP (Image Signal Processor) of digital cameras. The proposed method fuses multiple short exposed images which are noisy, but less blurred. Our approach is designed to avoid the ghost artifact caused by hand-shaking and object motion. In order to achieve a desired ISO image quality, both low frequency chromatic noise and fine-grain noise that usually appear in high ISO images are removed and then we modify the different layers which are created by a two-scale non-linear decomposition of an image. Once our approach is performed on an input Bayer pattern CFA image, the resultant Bayer image is further processed by ISP to obtain a fully processed RGB image. The performance of our proposed approach is evaluated by comparing SNR (Signal to Noise Ratio), MTF50 (Modulation Transfer Function), color error ∝E*ab and visual quality with reference images whose exposure times are properly extended into a variety of target sensitivity.

Citation Download Citation

Youngjin Yoo, Kangeui Lee, Wonhee Choe, SungChan Park, Seong-Deok Lee, and Chang-Yong Kim "A digital ISO expansion technique for digital cameras", Proc. SPIE 7537, Digital Photography VI, 75370U (18 January 2010); https://doi.org/10.1117/12.838774

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