[Tig] QC a DCP

Rogério Moraes rogermamo at gmail.com
Sat Feb 18 20:07:35 GMT 2012

...and back to the LUT and RGB2XYZ threads. Most DCP softwares come with a
player to play out you .j2c , 12 bit, XYZ, 2.6 gamma (wow) material and to
check if anything went wrong right after packging (though many only support
8 bit play). But, for a proper QC in my opninon, this should be done in
 the environment the DCP was supossed to play, A.K.A, a digital cinema
theatre, with a a calibrated DLP projector, and a (or two) trained human
eye present etc. Also, most  DCP softwares do come with a basic Rec.709 to
DCI compliant XYZ  color space conversion LUT. In the (not so) old days
when we (I) graded DPX for film out, I had to check my monitor in the
grading suite, run to the lab projection room, and to a certain degree say:
"... ok, we're almost there" . We kind of joked, because it was then we
"used" our LUT: a lab technician, in charge of the printer, to better
calibrate it so it matched with a fair good accuracy what I was seeing in
my monitor (giving lots of headroom to the video and film color space
changes). Never had the opportunity to do a " butterfly" check on a printed
material. wich is and was the best solution. But as far as your question
goes, I think that will be the differential that companies that offer DCP
services will have: a good Quality Check *person*, in my opinion, a trained
colorist, to validate not only the integretiy of the DCP, but the final
asthetical result, that was intendend in the master suite by him, the DOP
and Director.

Rogério Moraes

2012/2/18 Carl Skaff <carl at stopp.se>

> Sohonet http://www.sohonet.co.uk sponsors the TIG.
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> ====
> Hey all
> Here is topic for discussion.
> How do people QC a DCP?
> In the old days (not too long ago) we used to shoot out to Neg and then to
> a Print.
> Then the best way to QC the print was (if you ask me) to do a butterfly
> splitscreen between the digital projector (playing the graded DPX on your
> grade-system) and the analog film projector.
> That way we could check that the grade was ok and translated fine with our
> LUTs and we could determine if the added/removed grain/noise works fine
> with the filmgrain. Etc etc
> Now when we deliver DCP it should be possible to have a smart application
> that can play the graded DPX in splitscreen to the DCP.
> I suppose it should be fairly easy if you are on a DCI projector in P3, XYZ
> bla bla bla and all that.
> But if I was to grade on a Rec709 monitor/projector I suppose the app would
> need to be able to load the correct convertionLUTs on either side.
> That way we could QC the DCP, not only to check the convertion but also
> make sure that the compression didn't mess it up. And if we see an artifact
> we could just wipe over the original DPX to compare.
> Anyone know of such an app or am I thinking about this the wrong way?
> How do YOU qc your dcp?
> /Carl
> (Sent from mobile device)
> ____________________________
> *Carl Skaff*
> *Colorist*
> Stopp Stockholm
> Office +46 8 50 70 35 00
> *Stockholm | Los Angeles | Linz*
> www.stopp.se
> _______________________________________________
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> http://tig.colorist.org/wiki3

Rogério Moraes

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