Pressroom Illumination.

The apparent color or color temperature of a light source, as well as the spectral distribution of the light, will affect the appearance of a printed sheet. The effect may be sufficient to prevent satisfactory judgment even of comparative color and density. Thus, standard fluorescent lights are poor for examining the red end of the spectrum - for example, browns or red-tinted blacks. The physical, areawise distribution and brilliance of the light source have a profound effect upon the apparent optical density of the image on a relatively large press sheet. A lighting unit was designed which apparently is an effective compromise between initial cost, economy of operation, and spectral and areawise distribution.