A high capacity digital watermarking technique for the authentication of colour images

This paper deals with colour image authentication technique using a high capacity watermarking algorithm. The watermark is embedded into the green channel of the host image by modifying the very low frequency coefficients of the DCT transformation. The new algorithm can embed watermarking information in up to 25% of the host image size. The new technique can resist classical attacks such as JPEG compression, low pass filtering, median filtering, cropping, and scaling attacks. Moreover, the recovery method is blind since it does not need the original host image for extraction.