OPTICAL LOGARITHMIC TRANSFORMATION OF SPECKLE IMAGES WITH BACTERIORHODOPSIN FILMS

The application of logarithmic transformations to speckle images is so metimes desirable in converting the speckle noise distribution into an additive, constant-variance noise distribution. The optical transmiss ion properties of some bacteriorhodopsin films are well suited to impl ement such a transformation optically in a parallel fashion. I present experimental results of the optical conversion of a speckle image int o a transformed image with signal-independent noise statistics, using the real-time photochromic properties of bacteriorhodopsin. The origin al and transformed noise statistics are confirmed by histogram analysi s.