In the cinema industry, many movie piracy come from recording in the theater with a handy cam. The video watermarking system can be used to protect the those piracy. The watermark should be robust against various geometrical distortion. The auto-correlation function based watermarking is considered as a good solution resilient to the affine transform. But the suitable protection against the projection which occurs when the movie is projected at the screen and recorded with a handy cam doesn`t exist. In this paper, we propose a novel projection detection method. It is applicable to general auto-correlation function based image watermarking. The proposed method suggests a novel method of detecting possible projection attacks from watermarked image or video frames, while maintaining the conventional auto-correlation function based embedding technique. The experimental results prove the good performance of the proposed projection compensation method.