Non-Photorealistic Computer Graphics

2

PIXEL MANIPULATION OF IMAGES

The first approach to non-photorealistic rendering that we will pursue is to work on the level of the image’s pixels or of small marks. The input to such algorithms is generally simply a pixel matrix, where each entry is either a gray level or a color value (RGB). Indeed, we will concentrate on the former and show how to transform the gray levels to achieve various visual effects. In the terminology ofChapter 1, we will induce image artifacts for any one of a number of reasons. Although in the past many authors working on such topics considered these artifacts to be a distraction that had to be minimized, we will show how in many cases this apparent “bug” of having induced image artifacts can be made into an elegant ...