A compression subsystem for a computed tomography system compresses projection data to for efficient data transfer and storage. The compression includes detecting edges in the projection data corresponding to the object being imaged to set boundaries for compression operations. The edge detection compares difference samples to positive and negative thresholds to determine the boundaries. The projection samples or the difference samples are compressed between the boundaries. The boundaries are encoded and included in the compressed data. The compressed samples are decompressed prior to image reconstruction processing. Decompression includes decoding the compressed samples and the boundary values. This abstract does not limit the scope of the invention as described in the claims.