Details:
Summary:
A strictly empirical approach to halftone color reproduction has led to a set of equations relating colorimetric values to amounts of ink colorants. Red, green and blue colorimetric density readings of the original, substituted in the equations, yield per- cent dot sizes of the printers required for the correct reproduction of hue, saturation, and brightness. A black printer is also calculated which permits four-color reproduction using optimum amounts of the colored inks. The equations are in a suitable form to serve as the basis for the electronic computing phase of an optical scanner. Such a computing system might well solve many of the problems of the present systems. 610043 Exposure and Development Determination for Continuous-Tone Films and Plates. J. A. C. Yule 1961 43 52 discussion pp. 164-165 Gamma has been used in the past as an indication of the contrast of photographic materials, but it has not proved very satisfactory. An average-gradient measurement, known as contrast index, is proposed in its place. The relationship of the contrast index to density range is discussed. For the purpose of estimating the adjustment in exposure and development time required when a negative has to be made over, the use of exposure-development charts is proposed. These charts allow for the effect of reciprocity failure and for the change in speed which occurs when development time is changed. An alignment chart is given for calculating the exposure resulting from various light sources, lamp distances, exposure times, and original densities.