Hello everybody
I am exporting DPX sequences; for verifications, I imported the exported sequence to compare it with my original comp inside Flame. I found after setting the exposure high, these (stair/scale) artifacts. I tried 12 bits / 16 bits / linear / logorithmic, and all give the same thing; I tried to export in EXR 16 bit fp, and the result was good, isn’t there a way to get a dpx clean export similar to the EXR test. My project is set to 32 bits since I am using 32 bits input for the CGI elements.
It’s hard to diagnose without seeing the whole comp, but my hunch is you are rendering out linear files as 10 or 12 bit.
If your color space is linear and you export DPX’s, the dark areas will band up like crazy, because linear images have most of their data stored in the bottom quarter of the histogram.
In reply to @chadi’s comment in the Hand Paint Style thread, here is a quick workflow for working with integer (8, 10, 12-bit) files like DPX and mixing them with CG:
load all clips into batch, and convert them all to 16 bit FP.
You don’t have to do this to the CG, but 32-bit is overkill in every image-based instance. The only passes that are better at 32 bit are the UV pass, and Cryptomattes.
Use Color Management Input Transforms to convert all your imagery to Scene Linear to line up with the CG. For LogC this means Choosing LogC as the input format and ACEScg (or similar) as the output format.
Comp everything. Render out any precomps as 16 bit.
Once you are happy, make another Color Management Input Transform and reverse the input and output–go ACEScg to LogC. This will match your source plate exactly and not destroy any information.
there’s also this hasty tutorial I made that is related. I could ramble on about this stuff for days.
Hi Andy, I followed and carefully listened to your tutorials, very useful.
I want a favour from you if you can, here a 32 bits file from my comp, it matches precisely with the comp result. I just need to know, how I can export it to DPX without banding, everything I tried ended up with banding. My client insists to have the output in DPX rather than EXR.
I appreciate your help.
Take your time
That is a very dark image. I thought the download had screwed something up when I first loaded it. What lut are you using to view this?
Other things I want to know: What color space is this? What Color space do the clients want their DPX files in?
Note that “the comp is ACEScg and the clients want Arri LogC files back” would answer my question, but “It’s linear and the clients want log back” would not because the question is which linear, and which log.
Can you upload a jpg ref of what it should look like? A screencap of your monitor would be ideal, since I want to see it as you are and not in some other way. It’s fine if it’s banding, I just want it for the saturation and luminance values.
Here is a setup that shows you can take the image into a log space and get it back to linear (not that you should need to take it back to linear in this case) even when rendered out at 10-bit. ColorSpaceFun.zip (95.7 KB)
Hi Andy
Thanks for the efforts, I took a look, and honestly it is very important.
My issue between taken rendered shots in EXR from a company, making some adjustments on them, and delivering those to a client that doesn’t communicate technically what he wants (his colorist just says dark area and/or highlights miss details / in Chinese ) makes my task really hard.
I am allowing myself again to share with you one frame with a very simple batch of what my work consists of, I also included one frame of the live action that would sometimes intersect with CG in other shots. Any feedback would be appreciated, I know it is not a customer service that you are helping with, but maybe this will shed light on the problem and the way to export the final DPX.
BTW the viewing LUT I am using is Linear 2.4, I don’t remember how I ended up choosing this mode, I included a screenshot too.
Many thanks
The DPX looks like it’s Slog3 to me, but also looks pretty good when interpreted as LogC, ACEScct or ADX10. Given the generic feedback you are receiving, you can probably get away with converting to any of them.
The good news about “linear 2.4” is it’s just a 2.4 gamma boost (you get the exact same look by bypassing the monitor and adding a CC with 2.4 gamma). The bad news–with that and everything in the horrible “Legacy” color management template–is it’s the wrong way to view and work with media and there aren’t “correct” ways to get it into ACES and looking correct if you are used to looking at it with the 2.4 gamma.
What I did (and I’d love if someone had a more correct way to do this) is I applied the 2.4 gamma with a color correct node making the image rec709, then used an inverted view transform to go from rec709 to ACEScg. Once in ACEScg I converted the image with an input transform to Slog3. If your clients want a different brew of log, you can just change it on the last node.
