DPX transcoding for grade and VFX

[Dan Moran]

I don’t do that if I can help it but say for example my last job was a short film.

I graded the original files for most of the film but there was about 10-15 VFX shots and for those I did a pre correction grade which was fixing any major issues but no look etc.. rendered to dpx and when I got the shots back from the guys I applied the final look with no issues. Also a 10 bit DPX file should be more than enough for grading.

D

Dan Moran
DaVinci Application Specialist
Blackmagic Design EMEA

[Dylan Hopkin]

Stig,

Extracting the DPX-files with RedLogFilm / REDGamma3 (or 2 if you don’t have 3) is fine. It is pretty common practice for feature film and commercial work. Make sure you use “use meta from each shot / metadata as shot” to retain metadata used in the camera on the shooting day.

I tend not to use RMD / RSX data. Since we do not want to “bake” a look in to the ungraded DPX files.

(Yes I know that white balance, iso etc is tweakable metadata on R3D)

Good DOPs should have shot this correctly / well balanced.

A good safety precaution is to check that nothing “clips” in the histogram. If all the detail is retained, you should have all you need for grading.

I would not recommend pre-grading before VFX.
Most high-end VFX houses have LUTs for RedLogFilm, or at least RedLog.
The LUTs are only used for viewing while comping.
If you want to give the VFX artists some bearing on how the intended final grade will look. You can always make them a custom viewing-LUT so that they have better understanding on the “look”.

Basically when the finished vfx-comps come back the colorspace / gamma should be indenticle to the original “plate” you delivered.
Depending on how “heavy” the VFX are of course.
For typical rig-removal-shots the “plate” and “comp” should be exactly the same colorwise. If not, then usually the VFX Artist has exported with their viewing LUT still on.

Use RedCinexPro / Monkey Extract / Da Vinci for R3D to DPX extraction.

And you loose the ability to tweak “RED metadata” when going to DPX.
But this is not a problem!

There are many thoughts concerning how to this type of work, but this works fine for all the VFX-houses I’ve co-operated with over the years 8.)

—
// Dylan
Online Editor / Colourist
Nordisk Film ShortCut Norway
Showreel: http://www.dylanhopkin.com
IMDB: https://www.imdb.com/name/nm4104429/
Twitter: drhopkin

[Dylan Hopkin]

Stig,

I must correct something:

RedColor3 / RedLogFilm is what I meant, not RedGamma3 / RedLogFilm…… a major typo!

—
// Dylan
Online Editor / Colourist
Nordisk Film ShortCut Norway
Showreel: http://www.dylanhopkin.com
IMDB: https://www.imdb.com/name/nm4104429/
Twitter: drhopkin

[Stig Olsen]

Thank you Dylan,

So that basically means that you change to RedColor3/Redlogfilm before the DPX extraction?

And by “LUTs for RedLogFilm” you mean a viewing LUT that is apply afterwards in Flame/Smoke etc, that “converts” the dull/flat redlog DPX-files to something more contrasty that is possible to work with?

If you work in After Effects, do you follow the same procedure with applying an viewing LUT or do you use ICC profiles configuration instead to achieve the same?
If you use a LUT I guess it doesnt matter much what kind of LUT that is used, as long as it gives the VFX-artist a good starting point – since the LUT is disabled when rendering anyway?

Stig

[Philipp Meier]

Very interesting discussion! This is my first time with Resolve and I’m still learning the ropes. I was tempted to export DPX with REC709 and Redcolor3. However, I understand that RedLog(Film) would preserve much more data.

Is there a RedLog(Film) LUT that I can use in Resolve once the VFX shots are returned to me? I dont think I’d be able to grade log footage so that it looks nice again. Just don’t have the experience.

Any workflow suggestions once you get those log DPX shots back from the VFX house?

(also would you recommend RedLog or RedLog film? This is for a web/tv production. Not film out)

Thanks!