[argyllcms] Re: Dispcal and black point
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 13 Aug 2010 10:15:22 +1000
Marco N. wrote:
On my NVIDIA GeForce 7300 GT I can't set the black point to 0 (native). Dispcal
seems ignore the -k0 -A1 -f0 settings and it correct always the three gamma
curve of the LUT.
http://lh5.ggpht.com/_Ogy3SF4bQ9Q/TGQ9niAuPKI/AAAAAAAAAIk/jzWMEBz18P4/s144/1.png
Is it a bug?
No it's a feature!
A calibrated display should have a progressive response.
This means that from 0 giving the minimum output, it should
start to change as soon as you change the input.
If a display native response has a "dead band" where nothing changes
as you change the input, then this results in a vertical jump
in the calibration curve.
So the curve you see indicates that your display doesn't change its
output until it gets (about) 5 as in input, so the calibration curve
starts at (about) 5, so as to give a progressive response.
Graeme Gill.
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