Clipped pixels in HSL-L

[tomczak]

Would it make sense to have HSL-L channel for the clipped pixels as an option in Preferences or a toggle button in toolbar? HSV-V is typically more useful as it shows pixels blown in at least one RGB channel, but sometimes I was hoping to map just pure white as well (my camera does it this way).

[jsachs]

While personally I think it is more important to know if any of the channels has been clipped, for the next release, I have added a second clipping color to the File/Preferences dialog box which applies when all three channels are clipped, so you can distinguish this case if you want.

As to what cameras are using to determine blown highlights, there is no way of knowing - luminance clipped? all channels clipped?. I have believed for years that camera histogram and clipping alarms should be HSV-valued based. It took me a long time to figure out why some photos of saturated red flowers had no highlight detail even though the histogram looked fine. Of course, some cameras let you display three histograms, at least in playback mode, but they are too small and there is no histogram expansion option.

[tomczak]

Thank you!

And for what it's worth, I couldn't agree more with what you said above - it's the warning that at least one channel is blown (HSV-V) that has more practical value in most cases. It's also true that I really have no idea what Fuji histogram is showing, but it is definitely not effective in a warning if just one channel is clipped.

I once even experimented with something called UniWB (http://www.guillermoluijk.com/tutorial/ ... dex_en.htm) - the idea is that you set the WB in your camera so that the preview and the histogram is close to displaying the values that you would find in RAW file, and thus can help you from keeping the RAW data from clipping, then apply the proper WB in postprocessing.

While a clever scheme, this became too much of a science project than photography to me and I dropped that scheme and the in-camera histogram entirely to make things simpler, as they used to be...