Photoshop CC 32 bit float linear workflow is developing nicely but it still lack some needed basic components, and one of them is a Clamp Color Adjustment, equivalent to a node you will find in any 32 bit float HDR capable compositing software.
Clamping the colors means limiting the britest values to set values, usually 1.0 – white and 0.0 – black, so that no pixels will have higher than white or lower than black (negative) values that can create unwanted results in further operations.
* Brighter than white (super-whites) and negative colors are a feature, and part of linear 32 bit float color processing.
* If there is such an option that I didn’t find please let me know..
In order to clamp the layers colors we convert it to a Smart Object, and convert its color depth to 16Bit internally, so the individual layer gets clamped but the main document remains 32Bit float unclamped (HDR).
From the Image > Mode menu, choose 16Bits/Channel,
And in the Conversion dialog that opens choose ‘Don’t Merge’, or choose Merge and then in the HDR Toning dialog choose Exposure And Gamma mode to keep the image unchanged. The conversion to 16Bit color depth without Merging or Merging using default Exposure and Gamma mode will clamp the colors.
Save the Smart Object.
Return to the main document, the layers colors are now clamped.