[argyllcms] Re: Aw: Re: Chartread i1Pro2
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 22 Mar 2021 21:30:44 +1100
0815xl@xxxxxx wrote:
Hi,
The rendering intent of my prints is absolutely colorimetric. I am using:
targen -v -d4 -G -f1056 NAME
printtarg -v -ii1 -L -P -a 0.75 -m0 -M2 -T300 -pA4 NAME
chartread -v -T0.1 NAME
colprof -v -qh -fM1 -cmt -dpp -D Beschreibung NAME
the rendering intent will be determined by the program that uses
the profile, not (usually) by the profile itself.
So the above gives no indication about what intent you are using.
Using Absolute Colorimetric during printing is typically
only used for side by side proofing or emulation of one
print process by another. Care has to be taken to
ensure that the target colorspace fits within the
gamut of the emulation print space, something that
depends critically on the substrate compatibility
and accurate profile white points.
I have the impression that photoshop is displaying the lab values
incorrectly. In
www.easyrgb.com/en/convert.php completely different values are displayed
which appear more
realistic. I manually create color fields in Photoshop, read the HTML
0-FFFFFF designation and now
read the Lab values in easyrgb.
It's likely to be about the intent Photoshop is using in computing the L*a*b*
values.
By default these are typically Relative Colorimetric.
Then measure the fields with spotread with FWA compensation and calculate the
DeltaE 2000. With
www.brucelindbloom.com/index.html?ColorDifferenceCalc.html
And measurements are almost certainly Absolute Colorimetric.
The manual measuring over spotread is very time consuming. Is it possible
generate test fields with
argyll (targen and printtarg), then assign TIFF in photshop to my
argyll-printerprofile. Then
print and measure with chartread and somehow find out the deltaE?
Sure. You just have to ensure that you set the correct profiles in the workflow
to measure
what you intend (I can't figure out from what you've described what you are
measuring.)
Profile check complete, errors(CIEDE2000): max. = 0.876041, avg. = 0.206185,
RMS = 0.249615
That's s self consistency check. So the measured data is consistent and fitted
well by the profile.
Cheers,
Graeme Gill.
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