Ripplet: A New Transform for Image Processing
Jun Xu, Lei Yang and Dapeng Wu
Ripplet: A New Transform for Feature Extraction and Image Representation
Dr. Dapeng Oliver Wu
Department of Electrical and Computer Engineering, University of Florida
傅里叶变换 使 微分方程 变为 代数方程，便于运算；变到频率域 分清主次 用于 压缩。
越变 会产生 无穷多的频率
Fourier transform —— Gibbs phenomenon
Wavelet transform can resolve 1-D singularities, but it can not resolve 2-D singularities
Ridgelet [Candes and Donoho] Resolve 2D singularities along lines
Curvelet [Candes and Donoho] Resolve 2D singularities along curves
parabolic scaling，不同于rotated 2D wavelet（各向同性）。
Contourlet [Do and Vetterli] Resolve 2D singularities along curves
Ripplet: Blocks with arbitrary shape and size, not good at 纹理
