Color image watermarking using wavelet packet transform

The paper proposes a new image watermarking technique for digital media that can embed a specified watermark image in the cover image without affecting the imperceptibility and increase the security of watermarks. Watermarking techniques based on DCT (Discrete Cosine Transform) and Wavelet Transform are studied, whereas by using wavelet packet transform the robustness of the technique can be achieved compared to other transforms. This paper urges an effective watermarking technique based on a Wavelet Packet Transform (WPT). Here the image has been divided into several bands using wavelet packet and in particular subband the watermark is embedded. The sub band selection is achieved by calculating the energy value for each band and suitable band is selected for embedding the watermark into the cover image. The extraction of watermark is carried out by taking the inverse transform to the watermarked image and with the help of cover image the watermark has been extracted. The Peak Signal to Noise Ratio (PSNR) value has been calculated to analyze the quality of image.