[argyllcms] Re: An argyllcms version of the TC.918 target.
- From: Roger Breton <graxx@xxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 11 Feb 2008 07:22:30 -0500
Hello Lars,
I'd be interested in looking at your adaptation of TC9.18. But before I do,
I'd like to understand why it is presumably superior to a an
Argyll-generated ti1 RGB target using a similar number of patches.
Perhaps we could start by a VRML of TC9.18? If such thing is available. And
then a VRML of some Argyll chart? That way, we would have some "logical" way
to compare both targets.
I always believed that the spacing of the patches within an Argyll target
was superior and therefore, could result in superior profiling. But if you
think that the Atkinson target knows something that Argyll does not know
about characterizing a printer RGB space then I say we all try to learn from
it.
Best regards,
Roger Breton
> Hello list and eye-one pro owners.
>
> I had an idea that support for a few standard RGB target with
> Argyllcms, and my eye-one would be a nice idea. There are two targets
> I often find mentioned on web sources, created by Bill Atkinson, I
> have in my mind. His TC.918 and his RGB 1728 chart. I have started
> with the former. I guess this is not rocket science, but I have
> actually spent some time with this. I ended up with a custom version
> designed more like a normal Argyll i1 chart. But the patches are the
> same; I only randomize it, and add 6 white patches just to get a full
> row. It means that my chart consist of 924 patches. The XYZ values in
> the ti2 file are actually measured values on Epson photo gloss paper.
> I tried first with a simple convert RGB to XYZ, but I get errors like
> "There is at least one patch with an very unexpected response! "on
> every row. The RGB values are identical to the values in the tc918
> ref file I used as a starting point. I also think is should work on
> both A4 paper and Letter sized paper, since I have added some kind of
> a ruler to the target.
>
> There where some things I don't understand in the ti2 format:
> Like STEPS_IN_PASS "21,20"
> I guessed this to be 21 patches in each row with 20 spacers?
>
> I also wonder if I should delete some of the black spacers at the end
> of some off the rows?
>
> I have tested it on a few papers and it looks like it works. If this
> chart is created correctly, and there is interest for it, maybe I
> should add this to the argyllcms section in the oyranos wiki?
>
> My beta version is here:
> http://www.mulebakken.net/div/argylltarget/
> The tiff files are created with the "-compress zip" option to
> imagemagick. I'm not sure if that's political correct jet?
>
> I have not started with the 1728 target jet.
>
> Regards
> Lars Tore Gustavsen
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