title: Adaptive predictive coding with applications to radiographs.
abstract: Picture archiving and communications systems (PACS) require storage and transmission of vast amounts of data. For design/cost considerations, it is desirable to reduce the size of these data without sacrificing the integrity of the stored information. The major considerations in designing a data-compression scheme for a PACS system are discussed: fidelity of the reconstructed image, bit rate, hardware complexity, and processing time. The basic principles of conventional nonadaptive differential pulse-code modulation (DPCM) are reviewed and compared with adaptive techniques. The effect of adaptive quantization on radiographic images is examined. Special consideration is given to block-adaptive DPCM or the "switched quantizer," which greatly enhances the system performance as compared with nonadaptive techniques, and conservatively has a 5:1 compression ratio. Sample radiographs substantiate the results.
mesh_terms: D001842:Bone and Bones / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007422:Intestines / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement / Q000379:methods*