[argyllcms] Re: Gamut mapping not-monotonic
- From: Vittorio Villani <vittoriovillani@xxxxxxxxxxx>
- To: ArgyllCMS List <argyllcms@xxxxxxxxxxxxx>
- Date: Wed, 8 Dec 2010 12:10:52 +0100
Thanks for you answer.
The fact is that the ColorMunki gives me different values each time I calibrate
and use it again.
Probably if I want better result I should get a more consistent instrument.
Have you got any experience with the ColorMunki. Is it normal that, after I
calibrate or disconnect the instrument, I can get a*b* values from -1 -1 to +1
+1?
I am using the ColorMunki software to get the L*a*b* values (ColorMunki Photo
ColorPicker).
The paper white of the paper (from the producer) is L=96.3 a=1.1 b=-6.8. I
think that there are OBAs inside, and what I get with the ColorMunki is a paper
withe value of 95, -0.8, -0.8
Anyway I am happy for the achieved results; the prints are the better I could
get from this paper. I am probably looking from something (a*b* values close to
0 in BW) that is not possible for my actual instrument.
Vittorio
> Date: Wed, 8 Dec 2010 19:23:13 +1100
> From: graeme@xxxxxxxxxxxxx
> To: argyllcms@xxxxxxxxxxxxx
> Subject: [argyllcms] Re: Gamut mapping not-monotonic
>
> Vittorio Villani wrote:
> > The BW seems to be more problematic.I made some measurement with the
> > ColorMunki (same
> > hardware used for the profile). I did 3 measurements for each value to be
> > sure that the
> > reading was correct. I will report the medium value.
> >
> > For black point (L*a*b* values in the file 0 0 0) I have an a* value of
> > about -1; L*and
> > b* are close to what I expected (4,2 and -0.2). For a grey point (L*a*b*
> > values 52 0 0
> > 0 in the file) I have 48.9 -0,8 -0.6. So what it seems that BW is a little
> > bit green
> > and not neutral.
>
> That's a delta E of 1. That's pretty good. Many would say it is excellent.
>
> In any case, the neutrality will be judged visually in comparison to the
> paper white. What is the paper a* b* ?
>
> How are you testing it ? If you are measuring it and using the measurement
> values,
> then you need to be feeding your target L*a*b* values into the absolute
> colorimetric
> B2A table. Naturally you won't get the target values if they are out of gamut.
> Is that what you're doing ?
>
> Graeme Gill.
>
Other related posts:
