Does anyone know of a formula that can be used to convert the L*a*b*
readings from measurements of, say, solid CMYK patches from a press
sheet
and convert the readings to the CMYK densities? In other words, a
method of
using a handheld spectrophotometer as a densitometer.
L*a*b* cannot be converted to CMYK densities. You must use spectral
data, combined with the filter functions for the needed Status density
units. For instance, if you want Status A densities then you combine
the Status A filter functions for the C, M and Y channels with the
spectral reflectance measurement. These density functions can be
obtained from various color standards and references.
You can use the Measure Tool from GretagMacbeth for their
spectrophotometers, SpectraShop 2 also calculates these values.
