A block based wavelet algorithm for watermarking still colour images captured by mobile phone cameras

This paper deals with a block based wavelet algorithm for digital watermarking of still colour images captured by mobile phone cameras. The algorithm use mobile phone numbers including the international code as the watermarking information. The host image is divided into 8×8 blocks and the watermark is embedded into one block of the LL sub-band coefficients of the green channel of the RGB colour image. The embedding is done into one of the higher weight coefficients of the LL sub-band. The algorithm is blind and does not require the original image for extracting the watermark. The watermarking caused minimal distortion to the host images and the PSNR is > 50dB. The robustness of the proposed algorithm is tested against several attacks and it survived cropping, scaling, filtering, additive noise and JPEG compression.