TO COMPUTER GRAPHICS BASED ONGKS Part I gives an introduction to basic concepts of computer graph­ ics and to the principles and concepts of GKS. The aims of this part are twofold: to provide the beginner with an overview of the terminology and concepts of computer graphics, based on GKS, and to give the computer graphics expert an introduc­ tion to the GKS standard. In the early chapters of this part, the main areas of computer graphics, the various classes of com­ puter graphics users, the interfaces of GKS and its underlying design concepts are discussed and important terms are defined. The later chapters give an informal introduction to the main concepts of GKS and their interrelationships: output, attributes, coordinate systems, transformations, input, segments, metafile, state lists, and error handling. This introduction to the GKS framework will prepare the ground for the detailed description of 2D GKS functions in Part III and the 3D extensions to GKS in Part IV. 1 WHAT IS COMPUTER GRAPHICS? 1. 1 Defmition of Computer Graphics The Data Processing Vocabulary of the International Organization for Stan­ dardization (ISO) [ISO 84] defines Computer Graphics as follows: "Methods and techniques for converting data to and from a graphic display via computer. " This definition refers to three basic components of any computer graphics system - namely "data", "computer", and "display".