ABSTRACT

The image compression framework consists of encoder and decoder functions used to compress High Dynamic Range (HDR) images. This chapter introduces the main techniques for HDR image compression. Some of these concepts are used or extended to HDR texture and video compression. The overarching method for HDR compression is to reduce the dynamic range using tone mapping and to encode these images using standard encoding methods. A JPEG XT encoder receives as input a pair of images: an HDR and an low Dynamic Range (LDR) image. The chapter shows the typical JPEG XT standard decoding workflow. It focuses on the compression of HDR textures, which are images used in computer graphics for increasing details of materials in a three-dimensional scene. The chapter describes HDR texture compression methods that are implemented in modern GPUs and available in graphics' APIs such as OpenGL and Direct3D.