Highlights Rolloff (Soft Clip) for Curves, Levels and Exposure

[shijan]

Essential task for any photographer to adjust exposure and same time somehow keep highlights unclipped.
Currently in PhotoLine there are few different ways to create Highlights Rolloff (Soft Clip):
- Using Exposure or Levels with Color Filter on top (works only in 32 bit document).
- Using Exposure or Levels with Optimize HDR on top (works only in 32 bit document).
- Using Curves (works in any bit depth document).

Each method have its own problems and limitations:
Color Filter creates strange curve shape with reversed brightness effect (it feels like a bug for me)

colorfilter22-.jpg

Optimize HDR rolloff looks more-less OK, but maximum possible Protect Brightness 75% knee is too large and starts too early.

levels-opthdr-.jpg

Curves can create any rolloff shape but complicated to operate. After adjusting curve exposure with hard clip, i need to create soft clip knee manually using few points. And if later i need to change exposure again, i need to build that multipoint knee from start again. This is very slow and uncomfortable. I tried to use single point curve with Bezier 2 and Spline 2 modes, but they can't keep main part of the curve straight and unmodified.

Soft-Clip.jpg

Possible ways to improve things:
- Fix problem in Color Filter or add special Soft Clip mode for it.
- In Optimize HDR Increase amount of Protect Brightness to 95% if it is technically possible in that tool.
- Add special Soft Clip slider for Curves, or add new mode for Curves that could keep middle section of the curve perfectly flat.

By the way, Soft Clip option was a part of Cineon system. Here is example screenshot from Blackmagic Fusion. Same option exists in Premiere, After Effects, Nuke and Shake.

cin2.jpg

[shijan]

I guess special "Control Cage" or "B-spline" curves mode combined with snapping points to cage could provide perfect curve to adjust Exposure + highlights compression:

"Control Cage
At first sight this curve type looks very much like the Custom curve, but there are some differences. With the Custom curve, the curve touches all the control points. This is not the case with the control cage curve – the control points attract the curve towards them but the curve doesn’t actually go through them. Another difference is that the control cage allows for a straight section of the curve, while you can't do this with the custom curve. The cage curve needs at least three points for that (so five in total). Holding down the Shift key while dragging a point will help you to easily create a straight line by snapping the point to the line made by the previous and next point (displayed in red by the 'snap to' tool). Many users prefer Control Cage type curves to the alternatives."

[shijan]

Highlights compression also could be done in 32 bit depth with Tone Equalizer applied after Exposure. Very useful and simple tool missing in PhotoLine (partially something similar to Whites, Neutrals, Blacks in Selective Color Correction). Here is how it looks in other apps:

Screen-Shot-2024-07-25-at-11-57-13-AM.jpg

Screen-Shot-2024-07-25-at-11-49-27-AM.jpg

Instead of sliders Tone Equalizer also could use curve similar to Hue Editor. Formally it is same tool as Curves, but arranged horizontally instead of diagonal:

Screen-Shot-2024-07-25-at-11-49-50-AM.jpg

Or simpler possible option - Highlights compression slider directly in Exposure adjustment.

Screen-Shot-2024-07-25-at-2-14-17-PM.jpg

[shijan]

Here is also interesting research and explanation about tone mapping and highlights compression module in free app PhotoFlow: https://discuss.pixls.us/t/new-film-lik ... eded/11018

4e7cf4adbb34754e9e4f518e63dba438728c6a89.jpg

[shijan]

Problem with Color Filter reversed brightness was fixed in 24.40b17. Seems source of the problem was very simple - in earlier versions Color Filter used max white value somewhere near 99.9% instead of true 100%. So if you want to match legacy look and feel of Color Filter, just set max bright value to 99.9%.

This bugfix will not helps with Highlights compression, because Color Filter curve is too rounded and starts too early to provide visually nice looking highlights compression.

colorfilterold-.jpg

colorfilter-new-.jpg

[shijan]

In 32 bit document Exposure in pair with Optimize HDR works more-less well for highlights recovery, but there is a small usability problem. Even if i set Optimize HDR to "Automatic" it don't updates automatically until i click to some value. I mean, if i adjust Exposure in bottom layer, i can't see updated "Protect Brightness" result until i click to Optimize HDR top layer and touch some value there.

So i was thinking, maybe it is possible just add special "Protect Brightness" (aka Highlights Rolloff or Soft Clip) slider directly to "Exposure" adjustment?

Screen Shot 2024-10-15 at 6.23.48 AM.jpg