4-14-1
4 Dot Functions
Dot Formula ............................. 4-1
Selecting Dot Area or Dot Gain. 4-4
Dot Area Function..................... 4-5
Dot Gain Function..................... 4-7
For dot measurements, you need to set some measurement
parameters. You need to select:
Ÿ The desired formula for dot measurementsthe Murray-Davies
formula or the Yule-Nielson formula (page 4-1); and
Ÿ the desired measurement functiondot area or dot gain
(page 4-3);
Ÿ NOTE: All dot function measurements are minus paper.
SELECTING DOT FORMULA
Dot is calculated using the either the Murray-Davies formula or the
Yule-Nielson formula. The Murray-Davies simply calculates dot by
comparing the density of the tint minus paper with the density of
the solid minus paper. Your 400 defaults to the Murray-Davies
formula for measurements.
The Yule-Nielson formula is similar to Murray-Davies, except that
it allows you to compensate for the amount of light that is absorbed
or “trapped” when a dot measurement is taken. This is done by first
dividing the densities of the paper and the solid by an “n” factor.
Using the Murray-Davies equation, your 400 instrument “n” factor
is simply 1.00, so the paper and solid densities are not affected.
Using Yule-Nielson, the paper and solid densities are multiplied by
an “n” factor value that is based on the properties of the substrate
material.
