Creative Coding with DCTL Part 8 – Refining UI Parameters

November 4, 2021

Colorist Cullen Kelly finished defining his Davinci Resolve DCTL plugin. Learn how he tweaks the interface, eliminating 'dead zones.'


Providing useful constraints on the user interface

In our prior Insight in this series, we’ve been focused on building our Filmic Contrast tool to offer greater creative control to the end-user. Now that we’ve built out the functionality we intended, we need to consider an equally important aspect of tool design: useful constraint.

The split-toning feature we incorporated in our last Insight is a powerful addition to the tool, but at the moment its maximum strength nets too aggressive a change in our image. There’s a large portion of the Blue/Green Shadows slider and Red/Green Highlights slider that produce visual results most users will find undesirable. If we can take these ‘dead zones’ out of play, we’ll end up with a tool that’s simultaneously stronger and simpler. We can also improve on the functionality of the tool by ensuring that the overall luminance of our shadows and highlights is unchanged when activating the split-toning effect.

In this Insight we’ll cover:

  • Manipulating raw user input to fall within the desired range
  • Preserving original luminance levels by scaling the output of the apply_shadow_split and apply_highlight_split functions

Let’s get started!

Evaluating our tool from the user’s point-of-view

After testing out the current version of our tool on a recent job, I have a few notes I’d like to implement for the next version:

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    • Scott Stacy

      Another winner modification. These changes are a must needed bonus to the previous version. Looking forward to the next “upgrade.”

      I, however, have noticed an interesting bug when using a RCM project (BMD and Arri) and the S-Curve setting in combination with Resolve Fx (specifically Lens Blur). It produces black artifacts. If you switch to Linear the artifacts disappear.

      I though that it might have been my code, so I went to Gitfront and downloaded your version. Same issue. There has to be something going on under the RCM hood that is not playing nice.

    • Cullen Kelly

      Thanks Scott! Yes, I’ve seen this too. I have some hunches about what it may be but no definitive answers yet.

    • Daniel P

      One more thing I would love to be shown how to do is a split toning roll-off which smoothly brings the highlights or shadows back to their neutral origins as well as a pivot slider for the split toning itself. I simply don’t know the right maths required to do that

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