Digital Image Steganography Based on Assignment Algorithm and Combination of DCT-IWT

In this paper a novel image steganography technique that combines the Integer Wavelet Transform (IWT) and Discrete Cosine Transform (DCT) is proposed. It embeds secret image in frequency domain of cover image with high matching quality by using Munkres´ assignment algorithm. Also, we embed the secret image in different coefficients of cover image bands such as horizontal detail, vertical detail and diagonal detail and observe the effect of embedding on the performance of stego image in terms of Peak Signal to Noise Ratio (PSNR), Mean Structural Similarity Index Measure (SSIM), Histogram Error (HE). Experimental results depict that stego image and extracted secret image could have high visual quality and they are perceptually similar to their original versions. In addition, this method shows high robustness against six different attacks. Also, our method is examined with wavelet based steganalysis algorithm. The results prove the effectiveness and benefits of the proposed method.