This release accelerates several algorithms using the Halide language. - Common GPGPU languages are supported: nVidia CUDA, OpenCL, Apple Metal (and possibly DirectX but not tested) - Acceleration of basic image processing functions (Gaussian convolution, scale-space pyramid, accute localization of scale-space extrema, histogram of gradients...) - Complete implementation of SIFT algorithm using GPU acceleration - Other non-GPU accelerated image processing functions: Canny edge detection, contour extraction, nonparametric image watershed