Multipurpose watermarking based on curvelet transform

Based on curvelet transform this paper embeds one leveled watermark onto significant coefficients by quantization in individual frequency scales. Watermark bits come from image HASH, which is defined in the paper. Bigger coefficients are used for watermarking for the conception that coefficient energy is proportion to its directional sensitivity and bigger coefficients are more stable. Watermark is extracted without resort to the original image. The proposed watermarking can realize multifunction of content authentication and copyright protection the same time.