METHOD FOR WATERMARKING DIGITAL IMAGE USING WAVELET TRANSFORM AND DISCRETE COSINE TRANSFORM

摘要

PURPOSE: A method for watermarking a digital image using wavelet transform and discrete cosine transform methods is provided to prevent watermark from being damaged by compression, filtering and truncation while the watermark is inserted into an image. CONSTITUTION: The original image is discrete-wavelet-transformed. A watermark image to be inserted is generated as a general image having the same size of the watermark image and discrete-cosine-transformed. The discrete-wavelet-transformed original image and the discrete-cosine-transformed watermark image are added up. The image added up is discrete-wavelet-reverse-transformed to generate an image into which the watermark has been inserted.