Digital Image Steganography Using Variable Length Group Of Bits Substitution

This paper presents two new steganography methods in spatial domain. The basic idea is the substitution of a group of bits in a pixel by another group of bits of same length to hide one or two bits of secret data. The number of bits selected for substitution in a pixel depends upon some pre-defined conditions. The first method hides one bit per pixel and the second method hides two bits per pixel. Although a group of bits are substituted in a pixel, but the maximum change in a pixel value is not more than 2. The security has been improved by making the group length variable for different pixels. In most of the cases the pixel value remains same, but it hides one or two bits of secret data. The experimental results are compared with other methods and found to be satisfactory. The security has been evaluated and found to be improved.