Graphics and Image Data Representations

Abstract

In this chapter we discuss how images are stored, starting off with the simplest image data, 1 bit per pixel. Grayscale, 8-bit images are considered next, and we consider the problem of how to actually send images to a printer and what problems and solutions this entails. RGB 24-bit color images are then explored, looking at the three color planes as images in their own right, and capturing RGB information content via a three-dimensional histogram of colors is introduced. Returning to 8 bits, the concept of a color palette is discussed; but this then brings up the problem of just what colors shall we distinguished by inclusion in the palette. To this end, the problem of how to devise a color lookup table is considered, with the Median-Cut algorithm brought forward as one solution. Popular file formats, GIF, JPEG, PNG, TIFF, PDF and so on are introduced. The GIF format is simple but representative, and for this reason it is set out in some detail. To wrap up the discussion the PTM (Polynomial Texture Mapping) technique and format is included, with the capability of virtually exploring the surfaces of cultural heritage precious objects.