Reference Book
Dot Gain scale :It is a quality control device used to indicate dot reproduction
of half tones and process colours. This scale consists of series of numbers
(zero through nine) that are finely screened and graduated from light to dark.
As dot gain increases, the numbers become more visible.Gray Balance Patch :Gray balance is measured by overprinting screen tints
of three process colours to see if they produce a gray balance patch of neutral
gray. If gray balance is not achieved the patch will have a tint. The midtone
percentage for a gray balance patch is 50% cyan and 40% of magenta and
yellow.
Register marks :They are designs or shapes placed in the non-image areas of
negatives, positives, colour separations and plates to ensure correct register.
Register marks help the press operators to align one colour over another in
perfect register. Register marks can either be purchased commercially as pre-
printed transparent materials or they can be created by drawing.
Densitometer: Densitometer is a colour measurement device that computes
the light-stopping or light absorption ability of an image or surface material. It
computes density or darkness of an image.
Spectrophotometer: It is the most accurate type of colour measurement device.
A spectrophotometer measures light intensity and different colours or
wavelengths of colours. Most of the spectrophotometers used in printing
industry are limited to reading light waves in the visible spectrum.