On Dec 10, 2003, at 1:08 AM, Jo Brunenberg wrote:
The discussion is not about the ECI CMYK profiles but
about advantages
(if any) of using ECI-RGB in a workflow.
I'm with you. I'm only discussing ECI RGB myself. The value of the CMYk
profiles I'm totally clear on.
I tend to agree with the following statements:
- Using ECI-RGB (compared to for instance Adobe RGB) does not bring
any advantages in terms of greybalance when converting from RGB to
(ECI-)CMYK.
Yes. And I find it odd that it was suggested a 1.8 gamma improves
shadow detail compared to 2.2 gamma. That's the exact opposite of my
experience as well as theory. Gamma 2.2 shifts more of the available
bits in 24-bit color to shadows, not the other way around. So this
still has me puzzled.
- Using ECI-RGB (compared to for instance Adobe RGB)
does not bring
any advantages in terms of other quality issues when converting from
RGB to (ECI-)CMYK
As previously noted, there is a distinct advantage to using a D50 based
space if you are making solid color callouts with intent to use AbsCol
rendering. And if it weren't for the silly scum dot problem with AbsCol
conversions, I have found quite a few images can benefit from AbsCol
conversions especially when being printed to output conditions that use
a substrate with a low L*. But that's another discussion really...
- Converting scanned images (with included scanner
profile) or digital
camera images (with included profile) to ECI- RGB only adds an extra
step in the workflow without adding any quality, so it is an
unneccessary step.
ScannerRGB->Adobe RGB *OR*
ScannerRGB->ECI RGB
I don't see the additional step. I think there might be a quality
increase in some colors with a small percent of images. So maybe in the
case it's a good thing to use ECI RGB compared to Adobe RGB. But I
think people must be very careful when enhancing images in wide gamut
spaces, including Adobe RGB. It is possible to enhance images in these
spaces to the point you will get disastrous CMYK conversions if the
image contains large amounts of important, fine, saturated, and out of
print gamut detail. It simply gets obliterated in the conversion.
Smaller spaces don't have this problem because you can't enhance the
image so far out of the CMYK gamut.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
---------------------------------------------------------
Co-author "Real World Color Management"
Published by PeachPit Press (ISBN 0-201-77340-6)