Computer graphics is in flux, and people working in the field are still busy creating vocabulary by minting new words. But they're also mutating the meanings of older words--words that once had a clear definition and context. Computer graphics is also an emerging field, in the sense that it is one fertilized by electronics, photography, film, animation, broadcast video, sculpture, and the traditional graphic arts. Each one of these fields has its own terminology and conventions, which computer graphics has inherited to some degree.
Complicating matters is that we're now in the era of electronic graphic arts. Color display adapters and frame buffers, paint and imaging programs, scanners, printers, video cameras, and video recorders are all being used in conjunction with the computer for the production of both fine and commercial art. A glance at any glossy magazine ad should give you some idea about how pervasive the mixing of digital and traditional media has become, if only because the overwhelming majority of magazines are now digitally composed. Indeed, the distinctions between traditional and computer art are becoming blurred.
Today we can find graphic artists producing work in traditional media, which is scanned into digital form, altered, re-rendered with a computer, and then distributed as original. While this is not a problem in itself, it nonetheless accelerates the injection of traditional terminology into computer graphics, countering any trend toward standardization. This will inevitably cause contradictions. Some are already apparent, in fact, and you'll probably notice them when we discuss the details of the formats.
There is no single consistent set of terms used across all of computer graphics. It is customary to cite standard references (like the classic Computer Graphics: Principles and Practice by James D. Foley, Andries vanDam, et al.) when arguing about terminology, but this approach is not always appropriate. Our experience is that usage in this field both precedes and succeeds definition. It also proceeds largely apart from the dictates of academia. To make matters worse, the sub-field of graphics file formats is littered with variant jargon and obsolete usage. Many of the problems programmers have implementing formats can be traced to terminological misunderstandings.
In light of this, we have chosen to use a self-consistent terminology that is occasionally at odds with that of other authors. Sometimes, we have picked a term because it has come into common use, displacing an older meaning. An example of this is bitmap, which is now often used as a synonym for raster, making obsolete the older distinction between bitmap and pixelmap. Occasionally, we have been forced to choose from among a number of terms for the same concept. Our decision to use the term palette is one example of this.
For some of the same reasons, we use the term graphics, and avoid graphic and graphical. We all have to face up to the fact that the field is known as computer graphics, establishing a persistent awkwardness. We have chosen to use graphics as a noun as well as an adjective.
We believe that the choices we made represent a simplification of the terminology, and that this shouldn't be a problem if you're already familiar with alternate usage. Should you have any questions in this area, our definitions are available in the Glossary.
This page is taken from the Encyclopedia of Graphics File Formats and is licensed by O'Reilly under the Creative Common/Attribution license.