Some Aspects of Optimum Ink Film Thickness in Color Printing.

In printing a color reproduction our concern is to obtain the optimum with respect to satisfactory reproduction of the original under the given conditions. More specifically the goal can be expressed this way, that (1) the largest attainable color gamut should be covered by the inks used (with the further consideration that gray is obtained using equal dot size halftones), (2) a certain minimum subjective blackness must be maintained. The most essential variable with respect to these requirements is the ink film thickness. The present investigation deals with the problems as they relate to 3-color printing. The work comprises two parts. In the first part the relationship between saturation and ink film thickness is considered. Emphasis is put on the interpretation of the measured results in terms of their visual effect. The second part deals with the question of the minimum black tolerable to the observers of a picture subject chosen for this specific test. The highest density in the picture was varied from around 1.0 to about 2.0. All visual evaluations were performed under a standard light source.