Image compression for radiology and telemedicine

High quality lossy image compression schemes which provide high compression rates are an important tool in enabling practical picture archiving communication and storage (PACS) systems for medical radiology. The most widely used lossy schemes have been transform based, typically using the discrete cosine transform (DCT) as a first step. Newer transform methods based on the wavelet transform have demonstrated higher compression for a fixed quality level. A discussion of the basic method common to all transform based image compression schemes is presented. Evaluation criteria for lossy compression schemes are discussed, and the criteria are applied to both DCT (JPEG) and wavelet based methods, concluding that the wavelet based methods provide better quality and higher compression for most source imagery, radiological and otherwise.