CGM and CGI

This book describes two ISO standardization projects - the Computer Graphics Interface (CGI) and the Computer Graphics Metafile (CGM). It has been written principally for users and practitioners of computer graphics. In particular, system designers, independent software vendors, graphics system implementors, and application program developers need to understand the basic standards being put into place at the so-called Virtual Device Interface. Technical managers, graduate students in computer science specializing in graphics, and buyers in government and industry will also find this book valuable. The CGI project is standardizing a functional and syntactic specification for the exchange of device-independent data and associated control information between systems with graphical capabilities. The CGI defines idealized abstract classes of graphical devices capable of accepting input and generating, storing and manipulating pictures. The CGM provides a file format suitable for the storage and retrieval of device-independent picture descriptions. Pictures described by a sequence of CGI function invocations can be written to disk and stored compactly as CGMs, and CGMs can be interpreted and displayed efficiently using a CGI implementation. Formal standards documents are difficult to read. They are dry, complex and lack tutorial material. This book is intended to supplement the standards documents themselves. Organized into four parts comprising seventeen chapters, it includes many illustrations and examples not found in the standards. The book also explains the relationship of the CGI and CGM to other standards, both formal and de facto, describes some early commercial implementations of the standards, and gives the reader insight into the future evolution of these standards.