Image compression by discrete cosine transformation

The discrete cosine transform (DCT) is now well recognized as one of the most important technique in image data compression. Among the class of transforms possessing fast computational algorithms, the cosine transform has a superior energy compaction property. Due to its simple implementation scheme, the DCT is wisely used as a substitute to the optimal Karhunen Loeve (KL) transform. In this paper, the discrete cosine transform is presented and an algorithm for its implementation is developed. The picture is firstly transform coded using 8x8 sub-blocks then a quantization and an entropy coding are used.