A novel and efficient 8-point DCT approximation for image compression

The Discrete Cosine Transform is widely used in the field of still image compression. Many integer approximations are given in the literature whereas the most of these transforms requires bit shift operations. This paper presents an efficient and low complexity integer approximation of the DCT for image compression. Our new approach involves replacing the bit shift elements of a variant of the Signed DCT transform by zeros, in order to eliminate the bit shift operations. As a result, all elements of the proposed transform are zeros and +/- 1. Indeed, the proposed transform retains all the characteristics of its original transform, such as orthogonality and high energy compaction capabilities, while generating computing cost savings. Experiments show that the proposed transform has a good compromise performance-computational complexity as well as state-of the-art DCT approximations. Moreover, an efficient algorithm primarily involving a small amount of arithmetical computation is well developed as no multiplications and bit-shift operations are required, with only 16 additions being involved.