[argyllcms] HDTV, IRE, and Rec709 - oh my.

  • From: Greg Soravilla <greg_soravilla@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 10 Nov 2011 15:18:58 -0800 (PST)

Fellow enthusiasts - I could sure use your insight.  Note this is in relation 
to using Argyll CMS to measure and adjust an HDTV.  (This may be long, so a BIG 
thanks to anyone who responds!)
Background:  I just picked up an HDTV (Zenith Plasma) with 20 point IRE 
settings (+/- R,G,B for each) and "color management" (color & tint adjustments 
for R,G,B,C,M,Y) in addition to the standard fare (bright/cont/color/tint/white 
balance).  While I found some suggested values for its LG cousin, I would like 
to leverage my colorimeter and PC to properly calibrate my particular set.  So 
far I have read what I can find, absorbed what I can (a good day of reading), 
and now have various facts, assumptions, and questions floating about in my 
Please, please, please correct anything that is wrong in any statements I 
make...  I want to learn and wrap my head around all this!!
My assumption/understanding of multi-point IRE controls is that they 
effectively map percentages of the incoming signal level (5%, 10%, etc) to an 
adjusted value for each channel (R,G,B).  The purpose of which is to fix 
gray-scale tracking.  My next few Qs are based on this (possibly incorrect) 
assumption, though the questions may still have some validity.
Can and should IRE also be used to fix anomalies/mis-tracking in gamma?  Does 
using the IRE controls pretty much dictate then that I have to pre-adjust for 
black and white points and that I cannot change the points later without 
redoing the IRE measurements and values?  (I guess I am loosely asking how 
brightness/contrast play into the IRE settings.)  Lastly, should the same IRE 
settings be applied to all my TV's inputs?  If not, do any overlap (eg, all 
The IRE tracking from input to input brings up another important question - 
what should I use for source(s) when calibrating?  If the IRE can be used from 
input to input, then is just my PC sufficient?  Or do I need a DVD to pop in 
the PS3 and HD-DVD players for their respective inputs?  If a DVD or video, is 
there anything suggested?  Cheap/free requested if feasible.  Not a 
requirement, though.  I merely have far more time than money.  ;-)
Would I likely be correct in assuming the TV's color management controls would 
remap source gamut points (e.g. 'red') within the color space of the TV's gamut 
(e.g. target rec 709 red)?  So red in the source actually lands on the correct 
place in the TV's gamut, instead of say 'orange-red'.  I realize this may a be 
manufacturer specific question - I just don't know if it is.  If so, any 
recommendations on out of gamut issues?  (Suppose I can't actually hit a proper 
red or yellow)
Is rec 709 using D65 and gamma 2.2?
Would I use the LCD or CRT attachment from a colorimeter to measure a plasma 
TV?  I assume CRT, but that could be wrong.
Any tips for nailing skin tones are appreciated.
If there are any good FAQs I have overlooked, please let me know.
I'm sure there are Qs I had that I already forgot.  That's enough for now!
Thank you everyone for any/all input,Greg

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