A Visually Lossless Data Compression Technique For Real-Time Frame/Pushbroom Space Science Imagers

A visually lossless data compression technique is currently being developed for space science applications under the requirement of high-speed push-broom scanning. The technique is also applicable to frame based imaging data The algorithm first performs a block transform of either a hybrid of modulated lapped transform (MLT) with discrete cosine transform (DCT), or a 2-dimensional MLT. The transform is followed by a bit-plane encoding; this results in an embedded bit string with exact desirable compression rate specified by the user. The approach requires no unique look-up table to maximize its performance and is error-resilient in that error propagation is contained within a few scan lines for push-broom applications. The compression scheme performs well on a suite of test images acquired from spacecraft instruments. Flight qualified hardware implementations are in development; a functional chip set is expected by the end of 2001. The chip set is being designed to compress data in excess of 20 Msamples/sec and support quantization from 2 to 16 bits.