METHODS FOR CHARACTERIZING CRT DISPLAYS

Computer-controlled CRT displays can be described by a two-stage model . The first stage consists of a linear transformation matrix relating radiometric scalars of each channel with either spectral radiance or t ristimulus values. The second stage is nonlinear and relates digital c ounts with the radiometric scalars for each channel. The term system g amma, Gamma, is introduced to define the non-linear stage. Gamma can b e characterized by either direct measurement or using a theoretical mo del with gain, k(g), offset, k(o), and exponential, gamma, parameters. Techniques and recommendations are given both to determine the transf ormation matrix coefficients and estimate Gamma using several methods. Special attention is given to Macintosh imaging systems. Key issues i nclude channel and spatial independence tests, including optical flare due to internal reflections, and problems arising from preset video l ook-up table entries.