Feature extraction is a vital part of watermarking technology that resists geometrically attacks.The points extracted from the image will directly influence the robustness of the watermak exists in the image.This paper improves Harris-Laplace corner detector by presenting a novel method to extract geometrically invariant feature points based on the scale space theory.According to the experiments

the proposed method can select those feature points that resist several geometrically attacks such as scaling and cropping

but at the cost of lower computation.