[argyllcms] Re: RGB Printer profiling and ColorSavvy CM2C

Gerhard,
Thanks for the info. I am using the raw "no colour adjustments" mode
of the Epson 2200 RGB driver, which is the same mode which Epson advises
to use for their own media-specific profiles. (I don't know whether
it meets that 1 dE per unit RGB requirement - it's very non-linear
so perhaps it doesn't). In this driver mode, there are no settings such
as "photo realistic", "vivid", nor individual controls for ink levels. 
(there is still an overall control for ink density though)

Note that I've received advice from Graeme
on a few Argyll parameters to twiddle which may result in an appearance
which is more to my liking. (haven't tried any of them yet)

Greg.

-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Gerhard Fuernkranz
Sent: Sunday, 31 July 2005 03:20
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: RGB Printer profiling and ColorSavvy CM2C

Greg Sullivan schrieb:

>I wrote:
>
>>My main concern at the moment is 
>>that saturated blues and magentas look too light and unsaturated.
>>
The root cause might be that the device gamut is actually limited in 
these sectors of the color space. This is not necessarily a limitation 
of the printer, but can also be caused by the driver - you're using a 
RGB printer driver, don't you? Have you tried different driver settings? 
Are you using a "raw" print mode (like the NCA mode of Epson drivers)?

I also had weak blues and magentas on my inkjet prints in conjunction 
with the manufacturer supplied Linux driver (RGB only) and 3rd party 
inks and paper. First I tried to move up the cyan and magenta sliders in 
the driver settings. This helped a bit to increase the saturation, but 
as a negative side effect, the more I moved the sliders up, the device 
response became more and more non-linear and "rippled", such that the 
profile could not follow the device characteristics any more accurately. 
My breakthrough was eventuelly, when I changed the "print type" from 
"photo" to "graphics" in the driver settings. I don't need to boost cyan 
and magenta any more, nevertheless the gamut is now definitively larger 
than it was in "photo" mode, and profiling also works better with this 
print mode :-)

Unfortunately, for RGB printers, profiling cannot generally compensate 
all flaws of the color mangling done in the driver. First you need to 
find a print mode and driver settings, which deliver maximum gamut, but 
still result in a smooth device response, with gradients of less than 
1dE per RGB unit at any location within the gamut. This can be a tedious 
try-and-error task, fiddling with various driver settings, which needs 
to be done manually first. Once you have found the optimal driver 
settings, you can start profiling ... But if you don't happen to find 
reasonable driver settings, then you are lost and profiling also can 
only partially compensate the deficiencies :-(

Regards,
Gerhard

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