[argyllcms] Re: i1 Photo rebate or i1Beamer upgrade

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 02 Apr 2008 11:56:48 +1100

Geert Janssens wrote:

- I suppose this complete darkness can also be recreated in other ways by carefully covering the lens opening of the i1 Photo ? - Is this spectro calibration standard procedure before profiling ? I mean, does ArgyllCms do this also and is it required ?

Yes, it's standard to calibrate the device before each use. In emission
measuring mode, it's usual to block the sensor using the white
reference, and calibrate the black level.

What I've done is simply calibrate it this way, and then put the
device in position. If you need to stop and start the
software, use the -N flag to avoid re-calibration while it's
in position. [ The previous calibration for that mode
is stored in a file, and will be read in each time the software starts. ]

- How can I point my spectro to the screen center using Argyll ? Does it also have some software trick for this ? Or are there some independent tools I could use for that ? Note that I am limited to linux, so using X-Rite's software isn't really an option.

It's really just a matter of making sure that the instruments field of view
is filled by the screen, and that it isn't seeing it's own shadow. If you
are operating with more than one display (so you can operate the
software without needing the display being measured), you can fill the
display being measured completely, using the -p parameters (e.g. -p 0,0,10 will
usually do it).

Also, imagine I manage to get the beamer/screen combo profiled. I suppose such a setup is even more susceptible to influences by ambient light ? I can't fully darken the room whet the beamer, so outside weather conditions will definitely play. In the end, I may have to go for Frédéric's procedure, and profile the beamer only.

Yes it will be influences by ambient light, and it will also be influenced by
stray light from the screen itself being reflected back from the surrounding
environment. This might be a reason for not filling the whole screen with the 
colors. But if the screen normally has a level of ambient lights, then there is
nothing wrong with capturing the way it appears, and going from there.

Graeme Gill.

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