Re: gamut volume and dot update issues
Re: gamut volume and dot update issues
- Subject: Re: gamut volume and dot update issues
- From: Roger Breton <email@hidden>
- Date: Thu, 22 Jun 2006 07:52:52 -0400
> Today I also learned, thanks to this list, of the printing issues
> with MacOS 10.4.6 and Photoshop 9.0.1. My first profile was built
> before these updates were installed but this last profile was built
> using MacOS 10.4.5 and Photoshop 9.0.1. I am seeing banding in the
> hue rainbow or Granger Rainbow with 9.0.1 but the rainbow is smooth
> when output from Photoshop 8.
>
> Would I be correct in surmising that this smaller gamut volume is a
> result of the printing problems associated with 10.4.x and Photoshop
> CS2 with the dot upgrade? It sounds like Colorsync is doing a color
> conversion where it should not based on what I'm reading in the Adobe
> forum.
>
> There should not be such a large difference in the gamut volume
> between 1440 and 2880, right? I was expecting the gamut volume to be
> very similar?
>
> Thank you,
> David Wollmann
ColorThink will yield useful statistics about the profiled gamut of your
printer, no doubt. But in order to test the problem for yourself though, I
would start by measuring the RGBCMYK 'solids' from your printed Monaco
testcharts. If you have the testchart measurements from CS and CS2, you
should see a difference between the two sets of numbers. Such that, if you
say printing through Photoshop CS2 yields a smaller gamut volume then,
logically, you should at least obtain CIE Lch numbers with lower chroma
values on the RGBCMY patches -- maybe not K. By lower chroma numbers you
know that you are actually getting a smaller gamut. It is intuitive to think
of chroma as expanding or contracting the gamut, everything else being
constant.
I take it from your choice of testcharts above that you characterized in
RGB. One thing you may want to keep in mind as you move forward with color
management is that profiling in CMYK (and printing in CMYK) will free you
from any RGB driver-related implementation issues, wherever it may come
from, be it OSX or Epson's own driver (I have to make an exception for
ImageByte type of RGB RIP which will not give you these troubles). For
instance, there is still a lingering issue when printing from InDesignCS2 as
compared with Photoshop or Illustrator (CS or CS2) to an RGB output device,
each program seems to be converting RGB to CMYK differently even though they
all use the same source and destination profiles. But this will never happen
when sending to a true PostScript RIP. There are many ways to color manage
your RGB image in this workflow. For starters, you don't have to convert
your images in CMYK necessarily before sending but your input to the RIP has
to be CMYK. Personally, I convert on the fly from RGB to CMYK in Photoshop's
PrintPreview dialog. That's one way. Another way is to setup the coversions
in the RIP. But please take the time to test the conversion, even if you
have a PostScript RIP. A client of mine use Postershop and converting from
RGB to the printer profile in the RIP results in a wrong conversion. That's
why, serving CMYK to the RIP is still the best route when everything else
fails -- but not through the Epson driver.
Since you say you're on OSX, have you investigated the possibility of
installing Gutenprint? The comments from this List members are all positive
(Edmund Ronald, Robert Kravitz and the others), and that should go a long
way towards freeing you from the Epson's drivers / Photoshop / OSX
vaguaries.
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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