Seung-Ki Cho

Alternating line high dynamic range imaging

In this paper, a novel method of improving dynamic range of imaging device is proposed. Unlike multi-capture HDR methods, the suggested method requires only a small modification to existing CMOS imaging sensor. By changing exposure time line by line, one can obtain a multi-exposure image in a single capture of an image. With such captured image, digital image processing algorithms are applied to recover the lost vertical resolution with minimal degradation. This paper will cover overall system issues as well as detailed description of the algorithms applied to recover high dynamic range image.

Texture preserving noise reduction for ultra high ISO images

We present a novel method to reduce a sparkle and impulse noise of high ISO images. We employ diverse approach for a intensity(Y) image and two Color images (CB,CR) separately. For the intensity image, we propose a frequency cut based texture analysis to distinguish between noise patch and texture patch. A noise analysis calibration is proposed depending on exposure time, ISO and sensor size for the parameter extraction. The intensity noise is removed by a frequency magnitude cut based noise reduction assuming that the pattern patch has much higher magnitude than noise patch. However the color parts produce big size of noise mass after CFA interpolation. We proposed a coincidental smoothing filter for removing the color noise mass by applying the Gaussian function to the strength of the color. Finally we blend an input noisy image to a noise reduced image and add Gaussian noise for making a natural image and reducing some pattern loss.