Ultrasound and angiographic image compression by cosine and wavelet transforms and its approval in clinical environment

The investigation results for improving lossy compression techniques for ultrasound cardiac and X-ray angiographic images are presented. The goal was to clarify where the compression process could be improved, and make efforts for its improvement. A lot of wavelet classes were tried for choosing the one best suited for the corresponding image class, which was defined by the image content complexity measure. The analysis of international image compression standards was carried out. Special attention was paid to the algorithmical and high level service structure of a new still image compression standard JPEG-2000. Its open architecture enables the inclusion of some wavelet classes which we would like to suggest for medical images. A set of recommendations for an acceptable compression ratio for different medical image modalities was developed. It was based on a compression study performed by a group of angiologists and cardiologists.