Z Transform Based Digital Image Authentication Using Quantization Index Modulation (Z-DIAQIM)

Abstract

This paper presents a novel Steganographic technique of color image authentication technique based on the Discrete two dimensional Z-Transform using Quantization Index Modulation (QIM). The Z-Transform is applied on sub-image block of size 2 x 2 in row major order of the carrier image for frequency components of the corresponding spatial components. Image authentication is done by hiding secret message/image into the real part of the frequency component of the carrier image. A single bit of secret message/image is embedded in each carrier image byte based on Quantization Index Modulation where a tolerance factor Δ has been used for invisible embedding. After embedding, a delicate re-adjusting phase is applied in all the frequency components of each mask, to keep the pixel values positive and non-fractional in the spatial domain. It is also applicable for secrete data transmission through carrier color image by hiding secrete data. Experimental results proof the robustness and performance of the proposed technique.