[Tig] Projector calibration question

Rob Lingelbach rob at colorist.org
Tue Sep 18 23:14:49 BST 2012


A subscriber sent this to me for posting.  It's being done through me to avoid corporate fluctuations.

The posting subscriber can be reached either via the group (if of general interest) or at this 
email address:

colourist at colorist.org

Rob    TIG admin/founder
--
Rob Lingelbach  http://rob.colorist.org




Hi all

I had  discussion today with my "probe-guy" about how to calibrate a Projector for normal HD work, Rec709.
what I'm puzzled about is this:

If I'm outputting from my Resolve a Legal Range (studio swing) signal, then that means that the actual code value I'm sending out for a black 0% image is in a 10bit world: 64 
and a white image at 100% will be: 940.
(in 8bit: 16 and 235)



So, in my mind, if I¨'m outputting Legal Range/StudioSwing taht means that whats below 64 and above 940 CLIPED OUT AND THROWN AWAY by the receiving projector or monitor.

BUT my probe-guy says that the standard is that the "blacks should be anchored at 64, white at 940. But extremely dark stuff should be allowed within the 0-63 codes and very high peak whites can live up in the 940-1023 codes"
(ok not his exact words, but this basically that)

So he says that when calibrating a projector the 100% (code 940) should be at about 12 fL and PEAK WHITE 109% (code 1023) should be at 14fL.

But I just think that is wrong. Code 64 should be at the lowest point of what the projector can display, and code 940 should be at the peak of the projectors output.



I can't think of any software in postproduction that is outputting LegalRange but not clipping at 64/940 and instead letting the deepest shadows and highest peakwhite through.
All software that I've ever used always hardclip to what I call 0% and 100%. Unless I turn it to FullRage/ExtendedRange/FullSwing but then the 0% is at code0 and 100% is at code1023.


I'm I completely wrong on this or is my probe-guy confusing all this with homecinema stuff?

colourist at colorist.org


More information about the Tig mailing list