Technique for large-dynamic-range wavelet image processing using coherent optics and binary SLMs

High speed spatial light modulators are typically binary in operation, which complicates their use as spatial filter masks when large dynamic range filters are needed. Wavelet image transformations may be implemented by a series of spatial filtering operations, but these filters typically must satisfy minimum uncertainty-principle or other constraints. For these constraints to hold, the amplitudes of the filter masks must closely follow the amplitudes of the appropriate wavelet kernel masks and therefore simple use of binary spatial light modulator (SLM) filter masks is impossible. A bit-slice method is therefore presented which can circumvent the dynamic range limitations of typical SLMs when used in coherent optical processors. The method takes advantage of the parallelism and linearity of optical processing and only results in a (log2N)2 increase in complexity for images with N gray levels. Computer modeled results are presented.