The word "render" isn't unique to the vocabulary of computer graphics. We can talk about a "watercolor rendering," a "musical rendering" or a "poetic rendering." In each of these, there is a transformation from one domain to another: from the landscape before the painter to color on paper, from musical notation to sound, from the associations in a poet's mind to a book of poetry.
An increasing number of artists and programmers in visual effects and broadcast production now use mental ray, a high performance rendering engine for generating photorealistic images. This book details the aesthetics of rendering with mental ray. It describes the varieties of shader programming from the point of view of increasing perceptual complexity: from color to the output of the final image. It includes many example shaders, including the simplest shader possible in each category that can serve as a starting point for further customization.