Digital Light & Color

Is there a way, in the Brightness Curve transformation, to probe the input (or output) image and display the lasting trace of the values below the histogram?

If the mouse is held by left click and the cursor moved around the main preview image (input or output), a faint red vertical line is displayed on the histogram, as the mouse move (in the dual histogram mode, the line is always displayed on the Output - lower- histogram regardless of whether the Input or the Output image is probed). The histogram also flickers (updates itself) quite frequently when this is being done. But I couldn't find a way to mark the ranges of probed points as it is possible for example in the Advanced Sharpen roughness histogram when moving shift-left clicked mouse around the image.

The Histogram tool can do this (click the Histogram button in the main tool bar). It has a separate eraser button to clear the accumulated red lines.

For the next release, I fixed the problem of the dual histogram probe showing up on the wrong histogram. I also changed the way the probe works so that as long as you click and drag, the red line accumulate. When you release the mouse button the are erased. I also fixed the flashing.