Adaptive coding of images based on the visual activity level

In this paper, a DCT based coding technique for adaptive coding of images according to the level of visual activity is presented. Adaptation is based on adaptive quantization and adaptive bit selection. In the proposed system, we initially partition the image into a large number of sub-blocks of 4 X 4 pixels. A novel image analysis may then be performed prior to the coding in order to decide what is the most significant information to encode. Classification according to the activity level within the blocks is based on the local statistics, and is used for adaptive bit selection, whereas optimum quantifiers having Gaussian density are used to achieve adaptive quantization. Satisfactory performance is demonstrated in terms of direct comparison of the original and the reconstructed images.