Compression Method in JPEG Standard

Abstract

Data compression is to minimize the communication and storage. The bandwidth and storage required for a given communication system. Data compression is obviated by wideband technologies such as optical fiber communication networks, packet radio and optical storage disk. Images can generate data in such high volumes that any transmission media can be quickly overwhelmed. Personal computers and workstations has led to an increasing demand to store images in compressed from on magnetic or optical disks. The massive efforts taking place today to adopt national and international standards for signal compression. Example is the JPEG (Joint Photographic Experts Group) standard for image compression. Compression in the image from RGB in JPEG standard converted to YCbCr. Each Y, Cb, Cr divided in block 8×8 pixel. The image 8×8 pixel then transformed use DCT. Image from DCT quantized yield DC and AC component. DC component processed use DPCM (Differential Pulse Code Modulation) use Huffman table yield AC bit stream. Merge DC component and AC component yield JPEG bit stream. To get image from JPEG bit stream first use Huffman decoding. From Huffman decoding dequantized. Then transform use IDCT. Image from IDCT merge block 8×8 pixel. From block 8×8 pixel transformed YCbCr to RGB. Then get the image. Process compression is consist of lossy compression and lossless compression. Lossy compression is compression with change of data but not change meaning of information in there. Lossless compression is compression not to change data.