Image steganography using single digit sum with varying base

Hiding an important message within an image is known as image steganography. Imperceptibility of the message is a major concern of an image steganography scheme. A novel single digit sum (SDS) based image steganography scheme has been proposed in this paper. At first, the computation of SDS has been generalized to support a number system with any given base. Then, an image steganography scheme has been developed, where the base for computing SDS is varied from one pixel to another. Therefore, the number of embedding bits in a pixel is varied across pixels. The purpose of this technique is to control the amount of change in a pixel. A lossy compressed version of the cover image is used to determine the upper limit of change in each pixel value. The base for computing SDS is determined by using this upper limit for a pixel. Thus, it is ensured that the stego image does not degrade beyond the degradation in the lossily compressed image.