Ok, thanks a lot for the tips.
I think the real problem is somewhere in my video player chain. Please take a
look at the attached measurements taken by HCFR software after calibration with
Argyll. The results are spectacular.....almost textbook!
It clearly tells me that the display is closely tracking the reference
luminance curve...........that means my blacks should be totally black and I
should have all the shadow-detail as is intended.
I think now it is a matter of the age-old problem of 16-235 or 0-255. Something
in my HTPC is keeping the desktop levels at 0-255 and the video player (media
center) is changing the video levels. I am not sure which one is which one ,
yet...........but will find out soon enough by experimenting.
BTW, I am shooting for a technically correct display, not subjective;
although my language may be pretty non-technical :-). I am a newbie here.
Hey, thanks for all your help!
Regards,
Rajiv Mehra
----- Original Message ----
From: Graeme Gill <graeme@xxxxxxxxxxxxx>
To: argyllcms@xxxxxxxxxxxxx
Sent: Wednesday, August 27, 2008 12:20:58 AM
Subject: [argyllcms] Re: Multiple issues with Argyll, please help
Rajiv Mehra wrote:
> Now while I have your attention, Graeme, what is the best way to prevent
> greyish blacks?
> even with this command........
> dispcal -v -y c -q m -w 0.313,0.329 -g 709 -p 0.5,0.5,1.7 -f1 -k0 g70-1
> ......while watching movies after dispcal......fade to black scenes have
> elevated brightness. Also, the overall image lacks "punch" .
> I think it is reducing the contrast/brightness to correct the greyscale or
> something.
If you are aiming for a non-native white point, then it will reduce
the maximum brightness, since channel values can only be reduced
from white. so try it without -w 0.313,0.329.
I'd be leaving -f alone (ie. not using -f1) unless you've determined
specifically that it gives you the results you want, since -f1 will
give a steep target curve that may reduce shadow detail near a non-zero black.
Note that inaccuracies in the instrument reading very low levels
may lead to a black that isn't quite as black as it should be,
although the i1d2 isn't too bad in that regard compared to
the Huey or Spyder2. The Eye-One Pro is probably better, as is
the DTP92 and DTP94.
Please note that since you're using -g 709, that you need to
use ambient compensation to get the desired subjective result,
or instead you should be using a gamma of 2.4, since this
is what Rec 709 TV encoded images are assumed to be displayed on
in a darkened viewing environment.
Since you seem to be aiming for a subjective rather than technical
calibration, it's really up to you to figure out what works.
Graeme Gill.
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greyscale-tracking.jpg
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