Image compression and gamma correction using DCT

In this paper an automatic image compression method is present. Image compression is done by modifying the gamma value of each pixels rather than applying uniform value of gamma like most of the exiting gamma correction methods follows. This method includes compression of digital images with the help of discrete cosine transform (DCT). To improve the performance of image compression, several encoding techniques are also used together with DCT. These techniques are Run length encoding and Differential pulse code modulation (RLE-DPCM). Both techniques are used separately on AC and DC coefficient of DCT of an image. In this algorithm, first the original image is divided into blocks where block size is also specified. Then these blocks are subjected to DCT. Through standard JPEG table each transformed block is also divided and then we set the coefficient of quantization table by scaling factor. The image performance is measured in terms of CR, MSE and PSNR.