[argyllcms] Re: Display calibration

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 02 Dec 2007 01:53:16 +1100

Frédéric Mantegazza wrote:
Yes, when using default 6500K white point, there is a little green color cast. But as soon as I load the LUT from the generated profile, using dispwin, the colors looks good: greys are greys. So, I think the instrument is OK.

I don't think this proves anything. If (say) the X channel of the
colorimeter was 50% of what it should be, you would get this
sort of result, since it is simply linearizing relative to
the white point it thinks it is measuring.

The problems occure when the color engine (all my softwares under Linux are based on LCMS) use the profile. I tried to profile my laptop LCD, and I got the same problem.

I'm using the Eye-One Display 2.

Something's wrong with it or the driver.

What happens if you use my profile ? Do you see this red saturation?

Not merely by loading the videoluts, no.

If I convert from sRGB to your profile using relative colorimetric,
and then view it on a normal display, it looks a little pink.
This may be due to the Chromatic adaptation matrix thinking
it's doing a very large white point shift, when it's actually
a small white point shift, in converting your measured values
from absolute instrument readings to D50 white point relative

> Could  it be better if I use a very large numbers of patchs (say 1000), and
generate a table, instead of a matrix?

I think you're on the wrong track. If the display is at all close
to 6500K, then the instrument is not reporting this correctly,
implying that there is a serious problem in that area.

Graeme Gill.

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