Robust image watermarking based on minimal DCT-quantization errors

The technique of the digital watermarking is one of the ways to resolve copyright ownership and verify originality of digital contents (e.g. text documents, audio, still images, video, etc.). In this paper, we obtained global robustness and minimal error through using frame based watermarking and including DC and AC coefficients of DCT transform, which extended conventional watermarking method having local robustness and error through using block based and/or AC coefficients only. As a result, the high robustness and quality of our method were proved by several attacks such as lossy image compression, linear filtering, additive noise, scaling, cropping and so on. Watermarks embedded by our method are survived most of JPEG compressions.