Resolve 15 Fusion: displays linear gamma; how to understand this???

DaVinci Resolve

Resolve 15 Fusion: displays linear gamma; how to understand this???

Posted by Michael Mccune on August 28, 2018 at 5:59 am

I understand that compositing, at which Fusion excels, is helped by doing its work in a linear gamma, not a 709 or log gamma. And color grading in log often is likewise preferred.

But here is a workflow problem with Resolve Fusion showing the images in linear gamma and I cannot find a way to apply a display LUT or whatever to bring it back to “normal.”

Starting with a new project and only a single log clip used for a source, Resolve shows the expected log image (low contrast, narrowed to the middle of the waveform scale) on the edit page and on the color page. It can be color graded as needed with no problems.

But opening Fusion directly from the edit page shows the clip in a linear gamma. That is, just select the clip on the edit page and then select the Fusion page icon to open into Fusion. The Fusion image displayed is in linear gamma, which of course–with wild extremes in color and luminescence–cannot be worked.

Likewise, use New Fusion Clip or New Compound Clip and the same linear gamma is displayed in the
Fusion display panes.

I see that there is a LUT icon above each Fusion display pane and they show a deep list of LUTS. But only a few seem to have any effect at all and none bring the displayed image back to a “normal” gamma.

Any suggestions in how to think through this situation??? How to understand the logic underlying all of this???

This seems to be new and I wonder if I set some preference parameter, though I have looked through all those settings and also through the 2,632 page manual.

Any thoughts??? Simon Ubsdell, are you listening???

Didn’t find any tutorials specifically on setting up Fusion to work in linear gamma though Juan Melara and Simon Ubsdell seem to have incorporated linear into their Resolve node chains to gain better control.

Thanks guys, Mike

Michael Mccune replied 8 years ago 3 Members · 3 Replies
3 Replies

Tero Ahlfors
August 28, 2018 at 6:14 am

You can either:

-Use a viewer LUT to set the viewer to show a gamma/gamut you can work in. This is only for viewing.
-Use a gamut node in the node tree

Note that the color tools in Fusion aren’t expecting linear so you might want to have a node to turn linear footage to sRGB, make a color correction node to do whatever you need, then add a node to turn it back to linear for further comping.
Glenn Sakatch
August 28, 2018 at 7:47 pm

If you are exporting dpx media to Fusion, you can select the clip, go to its properties and bypass the color transformation. If you render out to dpx, the saver will automatically add a reverse transformation, so check your saver and make sure it is turned off as well…or turn it back on for the source clip before rendering.

Glenn
Michael Mccune
August 29, 2018 at 10:01 pm

Glenn and Tero;

Does not seem to be a DPX (or any other format) export or import issue. The Sony Slog3 footage imports and displays in the edit and color pages normally and as expected. One can color the footage in the color page, sometimes even using the Color Space Transform tool to dip into another color space for a specific purpose and then back out. (BTW, found in someone’s tutorial that the ArriC-to-709 LUT shows a better 709 than the Transform 709 conversion. This LUT and many others are in the node context menu.)

Tero is probably right that a Fusion display LUT is what is needed. But I haven’t found one–after trying literally a hundred combinations of Project color management settings and Fusion display LUTs.

I do understand that the manual says that Fusion takes its color space and gamma from the timeline. But I have spent many hours trying Project color management settings and Fusion LUTs with no appreciable improvement.

I believe Tero is right but the result of all of my experimentation is simply no change at all in the linear display of the image. Which is baffling in itself. Or the changes that can be made may change the displayed image but only slightly.

Tero, do you have a suggested set of settings for my situation???? That is, a log source with your Project settings for input, timeline and output color space, and gamma, along with your specific Fusion Display Lut choice???

The goal is to have Fusion show an image that is not linear. Now Fusion always displays a linear (highly expanded luma and chroma) image.

Or perhaps I am missing something basic here.

Thanks again, guys. Mike

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