Reduction of photon shot noise using M-transform

This paper describes a novel approach for the photon shot noise reduction in an image sensor inspired from an M-transform method. In our proposed method, the photon shot noise is converted into small amplitude signals. Then, the signals are treated to remove the small amplitude noise by an ε filter. The Sobel method is applied to the edge detection. The edge of the object is protected by not treating the ε filter into the detect edge. After removal of the noise, the data of M-transform are restored to the image by a reverse M-transform. The proposed method is compared with the smoothing filter, the median filter and the Wiener filter. In cases where the number of the maximum incidence photons was 256 pieces (illumination is about 4 l×), the proposal technique indicated the PSNR (Peak-Signal to Noise Ratio) value better than the Wiener filter. Moreover, also with the low illumination less than 4 l×, the edge is maintained and the proposal technique is judged to be excellent in comprehensive evaluation.