Note 1 Each curve belongs to particular set of printing conditions.
Note 2 applies only to press printing and not off-proofing
Figure B.2 Dependence of tone-value increase of press print on screen ruling for an 80% tone value on the film or in a digital date file
Instructions for use The experimentally obtained family of graphs in Figures
B1 and B 2 are used yo convert a certain tone -value increase found with periodical screen of screen frequency F1 to that of that of a similar half-tone dot shape screen but with screen frequency f2 NOTE that figures b.1 apply only to press printing and not to off-press proofing
example1 the tone-value increase of a moderately elliptical screen with a 60cm screen ruling is measured as 12 % in a 40% mid-tone tint.what tone-value increase will be found with the same computer screening program if the screen frequency is set to 100? we look up 60 on the horizontal axis of figure B1,proceed vertically to 12% and follow the graph line till the right-hand edge which corresponds to 100%. moving horizontally to the left-hand scale,we read the resulting tone value increase as 16 %
example 2 The tone-value increase of a circular dot screen with 70 cm -1 measured as 12% in a 80% shadow tint what is the tone-value of a moderately elliptical screen with a 52 cm-1 screen ruling? We look up "70" on the horizontal axis of Figure B.2, proceed vertically to 12%, which is halfway between two curves. We follow the graph lines to the left till we are exactly above 52 cm -1. if the point halfway between the curves is again taken, the result is just below 10%. If the fact that a morderately elliptical screen has a slightly higher tone-value increase than a circular dot screen is considered, the final result is judged to be 10% or slightly above.