Histogram Tool colours

[tomczak]

I was wondering if it's my screen perhaps or maybe these could be made more visible/intuitive:

When shift-clicking on the image, red markers appear on the histogram correspondingly. The marks, on my screen, are v. thin (understandably) but also in what appears faint red. Basically, hard to see. Maybe changing their color to something more saturated could help?

In the RGB mode, all three channel histograms are displayed. The channels are semi-transparent in colour (which is great), but I have to think twice to guess what channel which histogram represents. Red is ok (shows pinky), green, well... fine. But the blue is distinctively purple (Abney effect?)...

[jsachs]

For the next release, I significantly reduced the transparency of the markers. I also changed it so that as you drag over an image markers get placed every time the mouse moves. Holding down shift is not necessary.