A System of Standardized Illumination for Color Viewing in the Graphic Arts.

In order to insure consistency in comparisons and criticisms among color originals, engravers proofs, and press sheets, Springdale Laboratories developed a system of standardized illumination which has been installed for use by photographers, art editors, engravers and printers. The factors which were studied before adopting the system were: geometry of the light source and viewing area, level of illumination, color temperature of the source, and spectral energy distribution of the source. Neither the chromaticity nor the color temperature alone is adequate as a specification of the color quality of the light. The spectral energy distribution must fulfill certain requirements, and the spectral energy distributions of transparency viewers and overhead illuminators must be approximately the same. The units which have been adopted include overhead illuminators with a combination of fluorescent and incandescent sources, giving an illumination level of 190 foot candles at the working surface at a color temperature of about 3600i K; and transparency viewers with the same type sources giving a brightness of 500 foot lamberts. Wherever these units have been installed they have been received enthusiastically and for the most critical color viewing the system is preferred to any previously used.