Image-based lighting (IBL) provides methods of accelerating the rendering computations lit by High Dynamic Range (HDR) images. IBL takes as input an image, termed the environment map that has captured illumination of the real-world environment for each direction. This chapter provides the main MATLAB code for converting between one projection and another. It presents the MATLAB code for converting the set of directions into a latitude-longitude representation. The initial image resize in the listing adjusts the input coordinates to have the same aspect ratio as the output mapping. IBL was used to simulate perfect specular effects such as pure specular reflection and refraction. Evaluation of IBL requires selecting a significant number of directions over the environment map. However a large number of these may be providing a minor contribution which would result in poor use of resources. A commonly used set of methods for the evaluation is to generate a finite set of directional light sources from the environment map.