Digital Image Watermarking using Modified DWT&DCT Combination and Bi Linear Interpolation

Abstract: This paper presents a robust Hybridized Watermarking scheme based on 3- level DWT (Discrete Wavelet Transform) and DCT (Discrete cosine Transform) using Bilinear Interpolation. The host image is subjected to DWT and DCT. The DWT coefficients of host image are modified with DCT coefficients of scrambled watermark logo to get watermarked image and then, various attacks are applied on this watermarked image to check the robustness. To enhance the quality of embedding logo, bilinear interpolation is applied to get optimal NCC value. Proposed method gives better results in terms of better image quality of watermarked image and robust watermark logo in terms of PSNR and NCC values.

Keywords: DCT, DWT, Bilinear interpolation, PSNR, NCC