Add a way to visualize clipping colors in the 2d viewer

[thiasbxl]

Can we please add a display clipping toggle in the 2d viewer. Like in Nuke it would display pure black pixels where any channel value gets over 1.0 and pure white pixels wherever any channel value gets negative.

this is part of #73

[johnhaddon]

Would I be right in assuming that this clipping should be applied after exposure/gamma and before the display transform?

[thiasbxl]

No the clipping must be applied right after the linear data is output to the viewer, same as color sampling/picking.

As a side note, It would be nice if we were able to choose to display clipped areas as colors. Red for overbright values and blue for negatives. This would make a lot easier to see when the input image/texture is greyscale.

[johnhaddon]

OK. So when you're dialing up exposure you're not ever thinking "let's see if it would it clip if it was twice as bright?" or anything of that sort?

My plan for implementing the clipping was to use Richard's clamp node, which won't give you red/blue, it'll give you per-channel 0/1.

[danieldresser]

Just had a chat with Mathias about this. He's OK with the per channel invert at the clipping point for the moment, and is quite resolute that having the exposure dial influence clipping would be weird.