On Apr 28, 2016, at 4:19 PM, Mark C <[email protected]> wrote:
- Its not much of a hassle to work in Adobe RGB. Just convert to SRGB before
saving for screen devices. …
It's not a 'hassle' to work with Adobe RGB. Any editing is a lossy process,
with Adobe RGB you lose less than you lose with sRGB, with ProPhoto RGB you
lose less than with either. It only makes sense to do your *editing* in the
greatest bit depth and largest color space you can use, and convert/downscale
color space and bit depth for output products.
- When it comes to printing - I may be wrong on this but I don't think that the Epson printer I use
is either an sRGB or Adobe RGB device. Basically there is a native color space for each type of
paper and a corresponding color profile. … The color space isn't sRGB or Adobe RGB, it's
"Premium Glossy" or "Enhanced Matte" or whatever... The color spaces for the
different types of papers can be fairly constrained (in the case of matte papers particularly) or
broad. It makes sense to use a wider gamut like Adobe RGB in source files for printing and let the
print process convert colors that are outside the destination gamut if needed. Epson i s
continually increasing the gamut of their inks and papers, so it seems best to preserve as much
color info in the source file as possible, in case you want to print it in the future.
Printers don't have a color space per se. They have gamut (the range of colors
they can produce) and Dmax (the maximum density they can produce). Both of
those are the combined characteristics of the printer's mechanisms, ink, and
paper used. An output calibration profile maps the colors represented on screen
in your image into the printer/ink/paper's Dmax and gamut.
Most higher-end printers these days do a pretty good job of covering the
standard sRGB colorspace. Adobe RGB, as I mentioned in another post, was
designed to emulate (or encompass, probably a more precise word in this
context) the gamut and density of a late 1990s CMYK web press, which is both
slightly larger in gamut and differently weighted from an RGB display.
- Printing via services - for low end services (drug stores, big box stores)
converting to srgb makes sense. Its a safe harbor - sRGB is the least common
denominator so odds are any printer can handle it. If you are paying any kind
of premium or working with a lab that holds itself out as having any kind of
professional status, they should be using a color managed process and should be
able to work with the profile embedded in your image.
Consumer print services generally presume sRGB or untagged images, so you're
safe with that.
Good print services (high-end, pro, whatever) provide instructions and/or
output profiles to optimize your image files for their printing process. Or
they'll tell you whether they want 8- or 16-bit, and sRGB or Adobe RGB to print
from.
From what I've been able to tell, monitors work within their native color
space, which may or may not correspond to sRGB or AdobeRGB or whatever. So a
monitor that is 78% of sRGB is just that - its native color space coincides
with 78% of the sRGB space. Some monitors can emulate certain standard color
spaces. I think this is what Igor was referring to when he mentioned that some
software assumes that the monitor is sRGB and can produce off results when a
wide gamut montior is actually used. But the color space used by the monitor is
not necessary a standard space, hence the need to use the manufacture's
profile, or calibrate with a colorimeter.
As I said earlier, sRGB color space was designed to *model* the native
characteristics of a high quality CRT. Obviously, not all displays are 100%
sRGB calibrated (or capable) as delivered. All displays, standard and wide
gamut included, benefit from calibration and profiling for the purposes of
being a reference display for editing. A good display profile is most
definitely NOT sRGB or Adobe RGB … It's a device dependent color calibration
profile based on the specific hardware characteristics of the display and the
graphics adapter used to drive its display.
Today's high-end modern displays have a built-in colorimeter and automated
calibration and profiling hardware and software.
sRGB, Adobe RGB, and ProPhoto RGB are device-agnostic color space standards
created to enable a standardized transformation of image rendering from one
machine to another, one display to another, enabling you to move files from
machine to machine and get the same rendered result. Rendering software that
honors color management takes the data from the image file, color space tagged,
and transforms it through the La*b* domain using the display CCP on your system
to show it to you. It similarly takes the data from your rendered image and
transforms it through the La*b* domain using the output printer calibration
profile to produce a high fidelity match on paper with ink.
For a complete discussion of this color spaces, color management, etc, see "Real
World Color Management (2nd Edition)" by Bruce Fraser and Chris Murphy. It is the
definitive work on the subject. (I knew Bruce from several workshops and classes he
taught back in the early 2000s. It was a very sad day when he passed away. :-()
G
