Efficient Post-processing with Importance Sampling

Introduction Texture filtering is a critical part in many rendering and post-processing methods. If we do it naively, the fragment shader needs to access the texture memory many times to fetch values in the neighborhood of the processed texel. This article presents an efficient filtering algorithm that minimizes the number of texture fetches. The algorithm is based on importance sampling and also exploits the bi-linear filtering hardware. We also present applications in one, two, and even in three dimensions, such as tone mapping with glow, depth of field, and real-time local ambient occlusion.