ABSTRACT
The OpenGL computer graphics API is primarily intended for rendering 3D synthetic scenes from geometric primitives, but some capabilities for manipulating images were built into the system from the beginning. With the addition of shader capabilities, OpenGL can now use texture access and manipulation operations to carry out a number of new image functions. In this chapter, we describe some of these functions. Our main tools will be the ability to get texels directly from a texture and the ability to do arithmetic on texel values.
