[argyllcms] Re: Display calibration - Hardware question

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 12 Jul 2014 13:39:39 +1000

János, Tóth F. wrote:

> After I upgraded my small toolset with an i1 Display Pro (i1d3)
> colorimeter (replacing an old i1d2), I started to question the benefit
> of creating correction matrices with my older ColorMunki Photo spectro
> (the old i1d2 obviously needed that but I wasn't sure if the
> ColorMunki Photo is any more accurate --- if not slightly but
> unequivocally less accurate ??? --- on a random display than an i1d3
> alone). I tried to read the opinions and look at test results of as
> many individuals as possible but it was very puzzling (some said the
> i1d3 is very accurate without corrections while the CM is NOT and some
> said the i1d3 still needs corrections and a CM grade spectro is still
> much more reliable), so I couldn't decide.

Hi,

The impression I get is "it depends". If your display is close to
one of the preset .edr/.ccss samples, then the instrument is probably
about as accurate as the ColorMunki Photo.

But if your display is not close to the preset samples, and you
happen to have an i1d3 that is at an unfortunate end of the filter accuracy
distribution (i.e. it's spectral sensitivities are not so like the standard
observer), then you may be better off creating a .ccss or .ccmx for it
using the ColorMunki. [ And some of the people with access to a lot
of i1d3's have commented that a few of them have not so good filter
shapes as the average i1d3. ]

> But now, my CM stopped working completely. It must be some kind of
> contact problem inside it's case: the device is accessible in the
> default measuring position but becomes unavailable in any other
> "dialer" positions, so self-calibration is no longer possible (and
> thus the device is useless). But I don't even care to try and possibly
> get it fixed because it's ~3 years old already, so it would be time to
> dispose of and get a fresh one anyway (especially when I consider the
> "i1d3: better of worse" question).

A few people have fixed this problem by carefully disassembling it
and repairing it. It's not too hard, you start by opening the
measurement guide and popping the clips out, then the plastic
covers, working around until they are all out. The only tricky
bit in the re-assembly is sorting out where the flexible PCB
that connects to the USB socket and spring go, as you put it
together. I'm not exactly sure what goes wrong with the position
detector though - I think it is optical, so should be reasonably robust.

> enough" accuracy in general (consumer grade HDTVs are never "spot-on"
> regardless how you calibrate them, just better than out of box...).

Some people have got very good results using hardware or software
than can apply a cLUT transform:
<http://www.avsforum.com/forum/139-display-calibration/1517849-comparison-3dlut-solutions-eecolor-box.html>

> So, what do you think? Should I go for an i1 Pro 2 and use it to
> profile my i1d3 or use the i1d3 alone in any case (even if I get a
> spectro for other reasons anyway)?

The i1pro2 is a nice instrument (apart from it's fussiness about
USB cables!), but it's a big expense if you just want to do
display profiling. Fixing your ColorMunki is probably a cheaper
solution.

Graeme Gill.

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