Legendre Transform Based Color Image Authentication (LTCIA)

Abstract

In this paper, a fragile watermarking technique using Legendre transform (LT) has been proposed for color image authentication (LTCIA). An initial pixel adjustment is used to ensure that it never exceeds the range of a valid pixel component. The Legendre transform (LT) is applied on each pair of pixel components of the carrier image in row major order. The transformed components of each transformed pair are used to fabricate one/two/three watermark bits starting from the first bit position (LSB-1) based on the perceptibility of human eye on red, green and blue channel. An adjustment method has been incorporated to keep the embedded transformed components closer to the original without hampering the fabricated watermark bits. The inverse Legendre transform (ILT) is applied on each adjusted pair as post embedding operation to re-generate the watermarked image in spatial domain. At the receiving end the whole watermark can be extracted based on the reverse procedure thus authentication is done through message digest. Experimental results conform that the proposed algorithm has enhanced payload and PSNR over Varsaki et. al’s Method [1] and SDHTIWCIA [2].