Blackmagic Forum

Hi, I'm currently grading a feature doc in 4K and P3 color space. I exported a temporary version without credits, which has been validated in a theater (after converson to DCP). I'm now exporting the credit sequence and for the life of me I can't figure out what's going on, the blacks are not at zero any more . Some time has gone by, I'm actually reopeing a project which I haven't worked on in a few months. I have NOT done any upgrades, still working on Resolve 16.2.6 on a 2014 MacPro running MacOS 10.13.6 (High Sierra).
I am exporting to DPX. MY original export is fine, i can reimport it, the blacks are fine, but my original timeline, which I exprted from has the blacks at 4 or 5%. And when I export my title sequence and reimport it, the blacks are clearly different from my previous export. I'm monitoring my signal through HD-SDI and an external Ultrascope. I've checked my settings, my timeline and output are in P3. To make things worse, when I set my monitor (a Flanders CM240 to P3 the image has a green cast to it). Also, Resolve is crashing quite regularly (yes I know I'm pushing it with this old mac...).
Anyhow, if someone thiks they may have insight to what's going on here...
Cheers,
Damien

earthling wrote:To make things worse, when I set my monitor (a Flanders CM240 to P3 the image has a green cast to it).

Not surprised. You used your FSI monitor set to P3 to grade this? Not something I'd ever do.

Tom Early wrote:Not surprised. You used your FSI monitor set to P3 to grade this? Not something I'd ever do.

Sadly, this is true. We always do theatrical trim passes in a theater, even if we just rent the room for a couple of days. It is true that DCI-P3 is 6300°K rather than the usual 6500°K of Rec709 (a bit greener), and I believe DCI calls for 2.6 gamma. From Wikipedia:

DCI-P3 uses a pure 2.6 gamma curve, a white luminance of 48 cd/m2, and a whitepoint with the same correlated daylight temperature as D63 but greener. DCI-P3 has a 25% larger color gamut than sRGB.


I react differently to big images on a screen vs. the monitors we use in post -- even a big 55" OLED screen doesn't have the impact of a 16' or a 20' projector -- and I tend to see little mistakes very easily in projection. I also find when they translate a Rec709 grade to P3 DCI, I tend to chase black level problems more than an anything else: it's not a predictable change.

If I were you, I'd make a copy of the timeline, try a global using a final node added to every shot as a "compensation correction," and see if that's a better starting point for DCI.