What problem do you see this solving?
Every image is different. Often when trying to fine tune highlights, Capture One does too much or too little.
Example. When making art reproductions of paintings, the image can be perfectly exposed for the flat plane facing the camera, however textures which are angled to face the light source can have blown out highlights because they are catching the light. The need is to reduce those blown highlights until they are back in range (the data is present in the capture). Using the highlights slider does not work in this scenario, it will attempt to reduce too many of the highlights in the image when only the brightest need to be affected, for example, I may only require only the L*96-100 to be affected.
If the Capture One highlights slider (or similar) had a way to adjust the tonal range affected so that only the desired highlights would be affected, then it would be easier to control the light on these angled surfaces.
Capture One already has a highlights warning which shows a colour to indicate areas that are out of gamut, ideally there would be a tool that adjusts only the blown highlights with minimal effect to the surrounding areas, which could produce a neat visual blend back into to the surrounding areas. For example, having a 'blown highlights' slider that only affects these out of gamut areas that has some user selectable controls to help it blend smoothly, while only affecting a the minimal possible range so the remainder of the image is not affected.
When was the last time you were affected by this lack of functionality, or specific tool?
With most art reproductions I make, there are highlights that need to be controlled. If you were to try and darken the whole image to get the angled highlights under control, the reproduction would be too dark and no longer have accurate tones.
Also for general photography, the highlights slider often doesn't select the highlights I have in mind, it's either too strong and selects too large a range, or not enough.
Are you using any workarounds or other solutions to achieve your goals in Capture One?
I have added a layer with reduced exposure, then used the luminosity range slider and possibly some feathering to try to select just what is required of the highlights. This has partially worked but also doesn't always select just what I need, sometimes the coloured areas can still be blown out of gamut when the white areas are controlled with the layer, but by expanding the affected luminosity range to, say, L*90-100, too much of the image is affected, particularly in the white areas, making the whites appear grey if too many highlights are selected in the attempt to pull back the out of gamut coloured areas as well. I have had to make a layer for white blown highlights and another that gets brushed in over more coloured ones.
The out of gamut warning mask seems like it would make a good starting point for a mask for this but it's not accessible that way, and if it was, I'm still not sure if it would work or not.
Are you happy to be contacted further about this suggestion or request?