Wavelet-based Image Compression Techniques for Medical Images

DICOM is a standard for handling, storing, printing and transmitting medical images. In every hospital, the diagnosis data is formatted by the DICOM standard, so as to make data compatible. High precision images are usually needed in medical diagnosis. But at the same time, the storage needed should be lowered.This is done by image compression. DICOM uses image compression standards like JPEG-LS, EZW etc to compress the medical images. There is always a tradeoff between quality and amount of storage needed. We want bitrate as low as possible and quality as high as possible. As there is a tradeoff, we may have to sacrifice one for the other. But in medical images, we cannot sacrifice quality too much as it may lead to wrong diagnosis. Presently we have very good compression techniques based on wavelets. In almost every field of digital imaging, these techniques perform well. Some of these techniques are wavelet difference reduction (WDR), Embedded Zerotree Wavelet (EZW), Set Partitioning in Hierarchical Trees (SPIHT) and JPEG2000.