Calculator for determining optimum tone reproduction

A method for determining optimum tone reproduction ot maximize color reproduction by use of a mid-tone calculator comprising positioning an original density scale and density compression scale on a base having a longitudinal guideway therein, shiftably mounting a lower slide and an upper transparent slide in the guideway with the upper slide overlying the lower slide and the upper and lower slides being relatively shiftable, placing a high density indicator on one of the upper and lower slides and a low density indicator on the other of the upper and lower slides and a plurality of tone reference number curves on one of the upper and lower slides and a tone intersect line on the other of the upper and lower slides, shiftably mounting a transparent cursor on the base, overlying the upper and lower slides and shiftable with respect thereto and having a half tone placement indicator thereon, arranging the base, lower slide, upper slide and cursor to be sequentially shiftable with respect to one another, determining a predetermined high density reading and a predetermined low density reading and shifting the upper and lower slides to produce alignment of the high density indicator and the low density indicator in accordance with the respective predetermined high and low density readings on the original density scale thereby causing the tone intersect line to intersect the tone reference number curves, and shifting of the cursor to a chosen point of intersection of the tone intersect line with a tone reference curve to bring the half tone placement indicator into alignment with a reading on the density compression scale to indicate a density for optimum half tone density position on the stand-in gray scale.