Thomas d'Auteuil

How do you accurately key in Log space inside Resolve?

Recommended Posts

I've seen the episode "Piping a key downstream" in the first color grading course. It makes sense to CST into rec709 to have a more accurate contrast and saturation to key in. However, it's a hassle to send keys to other nodes and potentially risking to break the node structure (I use ripple node changes on big projects).

Is there a way to have a "Log Space Aware" HSL qualifier? What's the best procedure to have accurate keys?

My goal is to have my keying done as cleanly as possible and changing the exposure of that key in log space (ex: bringing up the exposure in the skin).

Link to comment
Share on other sites
15 hours ago, Abby Bader said:

Most of the times you can key in log without any problem

Usually, it's feasible, but the luma and saturation controls are all crammed up in a tiny zone. It's overly sensitive and imprecise. More often than not, keys are much cleaner (and easier) in rec709. That's why I'm wondering if I'm doing something wrong, like not using the right qualifying tool.

Link to comment
Share on other sites

A colorspace aware qualifier would be the best solution. It would make sense to suggest it to BMD on the BMD forum.

As far as I know there is no simple solution other that keying in the timeline colorspace via a cst node.

Link to comment
Share on other sites

I usually have a key piping structure with a CST and a couple of parallel nodes present in a fixed node structures across all clips.

… or you could work in Color Managed Color Science 

But yeah, a color space aware picker would indeed be awsome.

Bildschirmfoto 2021-10-21 um 12.49.18.png

Link to comment
Share on other sites
(edited)

@Stefan Stark I totally agree. I tried using the key piping method, but it became too cumbersome on large projects. Instead, I simply got used to be ultraprecise in the luma and saturation selection.

I'll try messaging the people at Blackmagic to suggest a color space aware picker tool.

@Rune Felix Holm For now, I'm strongly considering converting my footage to rec709 in the middle of my node tree. I just don't know anything about how to grade in rec709 without messing up the gamma and introducing ugly tints.

Edited by Thomas d'Auteuil
Link to comment
Share on other sites

Pipe the mask output from the rec 709 node to your log nodes to stay in log all the way to the lut.

Stefans image shows how to set this up. All that is missing is to connect the key matte output to the log grading nodes.

  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.