Using graphics devices in reverse: GPU-based Image Processing and Computer Vision

Graphics and vision are approximate inverses of each other: ordinarily graphics processing units (GPUs) are used to convert ldquonumbers into picturesrdquo (i.e. computer graphics). In this paper, we discuss the use of GPUs in approximately the reverse way: to assist in ldquoconverting pictures into numbersrdquo (i.e. computer vision). For graphical operations, GPUs currently provide many hundreds of gigaflops of processing power. This paper discusses how this processing power is being harnessed for image processing and computer vision, thereby providing dramatic speedups on commodity, readily available graphics hardware. A brief review of algorithms mapped to the GPU by using the graphics API for vision is presented. The NVIDIA CUDA programming model is then introduced as a way of expressing program parallelism without the need for graphics expertise.