Abstract: A compressor and decompressor for CT scanner data first performs a lossless compression of individual CT sample value. After this compression, the compression ratio CR is calculated. This is compared to a target compression ratio. If the target compression ratio is larger or equal than the achieved compression ratio, and additional lossy compression is performed by reducing the number of bits of the lossless compressed values. Immediately after such a lossy compression a lossy decompression is performed within the compressor and the decompressed values stored as history for the compressor keeping the compressor and decompressor in sync. This allows for a better quality of decompressed data while achieving a higher compression ratio.

Abstract: A method and system for transferring data from a rotating data source to a stationary target over a slip ring. The system includes a compressor on a rotor, a decompressor on a stationary platform, and respectively corresponding memory buffers. The data is optionally compressed in the event that the slip ring capacity is below the required rate. The compressor a predictor unit, an entropy encoder unit and an error protector unit. The predictor unit may use stored data as reference from a set of frames and locations within them. Encoding of locations may be carried out with a Golomb-Rice encoded integer, and entropy encoding of differences may involve Golomb-Rice encoding with parameter K varying for each group of data units. The error protector protects parameters inserted into data stream with an error protection code while most of the data can remain without protection.