Performance evaluation of interpolative BTC image coding algorithms

Block Truncation Coding (BTC) is one of spatial coding techniques of images. This technique has a simple and fast algorithm which achieves constant bit rate of 2 bits per pixel. The compression ratio may be improved by coding only half of the bits in the BTC bit plane of each block; the other half will be interpolated at the receiver. The resulting bit rate will be 1.5 bits per pixel. In this paper, two proposed interpolative algorithms for coding the block truncated image bit plane are presented. Several gray scale test images are used to evaluate the coding efficiency and performance of these algorithms compared with existing algorithms. It is generally shown that the proposed algorithms give better results.