Image watermarking scheme resist to affine transformation and cropping

This paper presents a robust image watermarking algorithm in DWT domain. The watermark is embedded in the low-frequency coefficients by quantization modulation. In order to fight Geometric attacks, it adopts Scale Invariant Feature Transform (SIFT) to locate invariant key-points. And it uses the coordinates of the matched SIFT key-points between the original image and watermarked image to resynchronize watermarked image alerted by affine transformation and cropping. The experimental results show that the watermarking algorithm is robust against rotate, scale, translation, shearing. At the same time it achieves a good performance resisting common signal processing such as JPEG compression, Gaussian noise.