An efficient method of data hiding for digital colour images based on variant expansion and modulus function

Nowadays information security over unsecured communication channels has become one of the superior challenging issues in this highly digitalized world. These issues have led to the application of the cryptography technique as a mean for securing data by encrypting them. The purpose of steganographic techniques considers three main key issues: High embedding capacity, good visual quality and security. In this paper, we present a better information concealing approach based on variant expansion and modulus function. It presents an improved methodology of steganography which enhance the ability of the concealed secret data and provides the high security of the stego-colour image. The proposed method adaptively considers the suitable embedding direction for each colour scale according to the higher embedding capacity. However, the previous approach has only examined smooth areas of an image where the difference value is 0 or 1 while neglecting other values for data hiding. Due to this limitation, the result is a decrease in the embedding capacity for all images containing some straight ranges. Therefore, a developed new method that selects both positive and negative difference values to hide secret data. From our experimental results and discussion, we demonstrate that our developed method obtains a higher capacity with peak signal-to-noise ratio (PSNR) of 54.74 dB, 52.68 dB, 46.37 dB, 54.08 dB, and 53.21 dB, for the respective images. Furthermore, the proposed method is tested for its effectiveness on different types of standard colour images and results showed enhanced imperceptibility of the stego image compared to state-of-the-art data hiding methods based on encoding function while maintaining suitable image quality.