Fast Fourier transform based image compression algorithm optimized for speckle interferometer measurements

the framework of European Space Agency (ESA) FluidPac satellite mission, we have developed a fast, lossy image compression algorithm (ICA) based on a slight variation of the classical 2-D fast Fourier transform (FFT). In essence, given a monochrome picture, the ICA calculates (almost) its Fourier spectrum. It then applies a low-pass filter to eliminate all Fourier coefficients beyond a certain user-defined cutoff frequency. Finally, it further compresses by encoding the surviving FFT coefficients in a more memory efficient manner. The proposed scheme works best with pictures where the high-frequency data are of little value. This is precisely the case with electronic speckle pattern interferometer (ESPI) images. The ICA low-pass filter removes the speckle noise while preserving the useful scientific information: the interference fringe pattern. We have, however, also applied the FluidPac ICA to pictures generated by classical interferometers, photographic equipment, particle tracing instruments, and IR cameras. The results are extremely encouraging. (C) 1997 Society of Proto-Optical Instrumentation Engineers.