METHOD OF PRODUCING WAVELETS AND COMPRESSING DIGITAL IMAGES AND OF RESTORING THE DIGITAL IMAGES

To compress a digitized medical image, a first wavelet including quadrants respectively having LL, LH, HL and HH frequencies is provided, preferably in parallel. L and H respectively represent low and high frequency ranges. L and H representations may be respectively provided by averaging, and taking the difference between, two (2) successive pixels values. The first and second letters in each quadrant respectively refer to the frequency range in a pair of co-ordinates. A second wavelet may include, in the first wavelet LL quadrant, quadrants respectively having LL, LH, HL and HH frequency ranges. Successive wavelets may be similarly provided. Each wavelet is provided from the LL quadrant of the previous wavelet because most of the frequency information resides in the LL quadrant. Individual compressions may be provided in parallel of the representations in the LH, HL and HH quadrants in the first wavelet, preferably on a lossy basis (e.g. discrete cosine transform and then Huffman coding). An individual compression may be simultaneously provided of the LL representation in the first wavelet and the LL, LH, HL and HH representations in the second wavelet, preferably on a lossless basis (e.g. Huffman coding). Decompression may be provided by performing the inverse of compression. The pixels may be restored after decompression by reconstructing the pixels from the wavelets in steps inverse to those in obtaining the wavelets. Thus, the information transmissions time is minimized with little reduction loss.