Re: need help with inkjet proofs
Re: need help with inkjet proofs
- Subject: Re: need help with inkjet proofs
- From: email@hidden
- Date: Mon, 6 Nov 2000 14:55:05 EST
In a message dated 11/5/00 8:48:50 PM, email@hidden writes:
>
One thing I have found - after looking at device gamuts in 3D - is
>
that most of the Epson ink jets do not produce the shadow colors that
>
a press or proofing system will. This means that you will see very
>
grey or otherwise thrashed shadow colors on the proof.
This is a tricky one, Steve. The first question is whether the press truely
has a wider dark gamut than the Epson, or whether the Epson is not being run
with rich blacks and maximal dark combinations, which will vary drasticly
with the profiling software, the settings, and the paper. If we are talking
about a profile for the RGB driver, then these capabilities are not even
available; so a true CMYK RIP with ink control features in the profiling
software are required to even determine the Epson printer's capabilities.
Next we have the issue of how well the profile graphs actually represent the
device; two profiles that produce indistinguishable output for in-gamut files
can have drasticly different gamut maps in ColorThink, which is only
describing their outline, not how the contents of those outlines are
distributed. Beyond that we have to decide if any difference that is actually
a difference between the press output and the proofer output (not the 3d
representations of their profiles) is visually significant. This is an area
where delta-e values, and graphed differences, can be deceptive, as they do
not necessarily translate into significantly different visual results. The
eye is not at its best distinguishing between one formula for rich black and
another. Keep in mind that settings such as UCR, GCR, UCA, total ink and
total black will significantly change the shadow gamut of a profile. For
instance, increasing the total ink may have no effect at all unless UCA is
increased, as the ink is being limited not by the total ink ceiling, but the
UCA ceiling. This is (pardon the pun) a muddy area in ICC process.
C. David Tobie
Design Cooperative
email@hidden