Research On Optical Implementation Method Of Nonsubsampled Pyramid Transform

Wavelet can effiectively represent zero dimensional singular signal, but because wavelet is lack of directionality and wavelet base is isotropic, so it’s difficult to well represent the geometrical characters of image edge, contour and texture. While the edge, contour and texture contains much information in which we are interested, wavelet is not the optimal representation in higher dimensions. Because Multiscale Geometry Analysis(MGA) can effectively overcome the disadvantages of wavelet transform and represent high dimensional geometric characteristics of image, so it’s an effective image-processing tool. However, high computational complexity of multiscale geometric analysis restrict the further development of its application. Compared to electronic information processing,the biggest advantage of optical information processing is high speed, parallelism and interconnectivity. In this paper, the implementation method of optical nonsubsampled pyramid transform is proposed, which is the combination of optical information processing and nonsubsampled pyramid transform theory.At present, the implementation method of optical nonsubsampled pyramid transform and corresponding filter design method has not been proposed. However, wavelet transform has some mature optical implementation methods, but none of these methods consider the characteristics of nonsubsampled pyramid transform. Therefore, combined with the feature of optical system and the theory of nonsubsampled pyramid transform, a mathematical model of the relationship between nonsubsampled pyramid transform and optical filter is established, then the principle and realization process of optical 4 f system are studied. At last, according to optical nonsubsampled pyramid filter and optical 4 f system, we can get the implementation method of optical nonsubsampled pyramid transform.Firstly, the development situation of Multiscale Geometry Analysis, optical information processing and optical nonsubsampled pyramid transform are expounded. Secondly, nonsubsampled pyramid transform theory, the principle of filter desiging and the principle of optical 4 f system are introduced. Thirdly, according to the characteristics of optical system, optical nonsubsampled pyramid filter is designed. Then, combined with optical 4 f system and optical nonsubsampled pyramid filter, we can get the implementation method of optical nonsubsampled pyramid transform. And the paper proves the proposed scheme is effective by simulation results and optical experiment.