DCT Image Compression by Run-Length and Shift Coding Techniques.

Abstract

The mathematical concept of a DCT transform is a powerful tool in many areas; it is also, served as an approach in image processing discipline. In this work an image is processed as three color channel. The correlated pixels values of an image can be transformed to a representation where its coefficients are de-correlated. The term "de- correlated" means that the transformed values are independent of one another. As a result, they can be encoded independently, which make it simpler to construct a statistical model. Correlated values are coded with run-length coding techniques while shift coding used to decode the DC term and the other five lifting values. In this work, we suggest to save the first five values from every block to keep it back without any significant errors.The obtained bit rates was extended to be within range (11.4 , 2.6), compression ratio (2.76 , 13.34 )the values of the fiedility parameters (PSNR) was within the range (31.61 , 46.21) for the lena test image in both sizes (128×128 and 256×256), and PSNR was calculated as average for the three color channels, red, green , blue