Re: Epson drivers and profiles - how do they work ?
Re: Epson drivers and profiles - how do they work ?
- Subject: Re: Epson drivers and profiles - how do they work ?
- From: Graeme Gill <email@hidden>
- Date: Wed, 19 Apr 2006 14:55:28 +1000
bruce fraser wrote:
Which version of Photoshop? (The options have differed across versions,
and so has the behavior.)
I'm trying this on MSWindows 2K, Photoshop 5.5
When Printer Color Management is selected, Photoshop sends the data and
the profile that describes the data. It looks like the Epson driver is
doing something to the data based on the profile. The reliable option
for just printing the numbers in the chart is Same as Source-that just
sends the data.
I don't seem to have a "Same as source" option on any dialog I can readily
see. After selecting "Print" from photoshop, there are three dialogs.
The first dialog "Print" has a setting "Space", which presumably sets
which space Photoshop sends the file to the printer. There is a choice
of profiles there, but not intent. Below that is the "Printer Color
Management" tick box.
If one selects "Setup", you get the next dialog. This has
no color related options. If you select "Properties" on
that dialog, you get the "EPSON Stylus Photo R1800 properties"
dialog, and in the "Advanced" tab, are the Epson color options.
After some messing around, I've discovered that most of my problems
were due to a faulty carbon based unit, selecting relative colorimetric
instead of perceptual, for some cases :-)
Some other discrepancies seem a little more mysterious, and have
gone away (could be ink cartridges running out while all this
is going on, and complicating the picture). I'm a bit puzzled
as to how Photoshop selects the intent it will use for its
output conversion. It seems to be using perceptual, but I'm not
sure where it's getting that from. It doesn't seem to be from
the CMYK setup, and there seem few other dialogs in this version
of Photoshop that let you set an intent ("Profile to Profile" being
the only other one ?)
So, now out of the five basic combinations, I get identical output:
(RGB = Monitor RGB = Photoshop working space)
File Photoshop space Use Printer C.M. ? Epson ICM Setting
1 Printer space RGB Yes Off
2 Printer space RGB No Off
3 RGB Printer space Yes Off
4 RGB Printer space No Off
5 RGB RGB Yes Printer space
So "Use Printer C.M. = No" and "Epson ICM = Off" have the same effect,
and the printer color conversion seems to work fine.
I've never been able to asociate custom profiles with the printer at the
OS level and get the driver to use them correctly, on either OS, though
it should in theory be possible.
Hmm. It seems to work for the particular combination I have.
On Mac OS, the paper-specific profiles are actually buried in the Epson
driver. The driver selects the appropriate profile based on the media
settings in the driver. I haven't looked at the Windows behavior at all
closely but I suspect that a similar arrangement exists there.
MSWindows seems pretty similar. In the system profiles directory
are a bunch of 9 Epson profiles, "SPR1800 XXXX", where XXXX describes
a different paper. The profiles themselves look conventional, except
that they contain 'drvn' and 'mdea' tags, which seem to be Epson
private.
The Epson configuration only one "profile" and one "intent"
for it's profiles. Third parties are each displayed, and offer
the choice of the usual four intents.
Graeme Gill.
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