The Jpeg Image Compression Algorithm

The basis for the JPEG algorithm is the Discrete Cosine Transform (DCT) which extracts spatial frequency information from the spatial amplitude samples. These frequency components are then quantized to eliminate the visual data from the image that is least perceptually apparent, thereby reducing the amount of information that must be stored. The redundant properties of the quantized frequency samples are exploited through quantization, run-length and huffman coding to produce the compressed representation. Each of these steps is reversible to the extent that an acceptable approximation of the original space-amplitude samples can be reconstructed from the compressed form. This paper examines each step in the compression and decompression. KEYWORD: Image Compression, JPEG, DCT, Quantization, Run-Length Coding.