Hierarchical Prediction for Lossless Colour Image Compression and Transmission Using OFDM

Digital images are usually encoded by lossy compression methods due to their large memory or bandwidth requirements. The lossy compression methods achieve high compression ratio at the cost of image quality degradation. Here presents a lossless color image compression algorithm, based on the hierarchical prediction. For the lossless compression of an RGB image, it is first decorrelated by a reversible color transform and then Y component is encoded by a conventional lossless grayscale image compression method. For encoding the chrominance images, a hierarchical scheme that enables the use of upper, left, and lower pixels for the pixel prediction, whereas the conventional raster scan prediction methods use upper and left pixels. Orthogonal frequency division multiplexing is one of the multi-carrier modulation techniques that transmit signals through multiple carriers. These carriers (subcarriers) have different frequencies and they are orthogonal to each other. Orthogonal frequency division multiplexing techniques have been applied in both wired and wireless communications, such as the asymmetric digital subscriber line and the IEEE 802.11 standard. Here use the orthogonal frequency division multiplexing as the modulation technique for the transmission of the compressed image.