The over-complete dictionary, which is built on anisotropic refinement and rotation of 2D nonseparable Mexican hat wavelet, can efficiently capture edge characteristics present in natural images.

• 利用二维不可分离、具有各向异性尺度的墨西哥草帽小波作为生成函数，这种函数构建的冗余字典能够有效捕获图像边缘轮廓特征。