Image Watermarking Using DWT_DCT

Abstract

Digital watermarking has been developed to protect digital images fromillegal manipulation. Discrete wavelet Transform (DWT) and Discrete Cosine Transform (DCT) are techniques used for digital watermarking. A combination of DWT and DCT techniques are used in this paper to meet imperceptibility, robustness and security requirements. Peak Signal to Noise Ratio (PSNR) and Bit Correct Ratio (BCR) measurements are used to study the effect of parameters: gain factor, threshold value, sub band, and image size on the watermark image. Many images are used toembed the watermark image and the effects of parameters on the extractedwatermark image are studied. Then the optimal parameter values has beenspecified.