SCALAR VECTOR QUANTIZATION OF MEDICAL IMAGES

A new coding scheme based on the scalar-vector quantizer (SVQ) is deve loped for compression of medical images. SVQ is a fixed-rate encoder a nd its rate-distortion performance is close to that of optimal entropy -constrained scalar quantizers (ECSQ's) for memoryless sources, The us e of a fixed-rate quantizer is expected to eliminate some of the compl exity of using variable-length scalar quantizers. When transmission of images over noisy channels is considered, our coding scheme does not suffer from error propagation that is typical of coding schemes using variable-length codes, For a set of magnetic resonance (MR) images, co ding results obtained from SVQ and ECSQ at low bit rates are indisting uishable. Furthermore, our encoded images are perceptually indistingui shable from the original when displayed on a monitor. This makes our S VQ-based coder an attractive compression scheme for picture archiving and communication systems (PACS). PACS are currently under study for u se in an all-digital radiology environment in hospitals, where reliabl e transmission, storage, and high fidelity reconstruction of images ar e desired.