Show clipped pixels in RAW dialog

[bogumil]

I can't help the feeling that "Show clipped pixels" option in RAW dialog is not working. I'm doing exaggerated changes to the histogram and cannot see any difference between off and on states of this option. Has anobody actually seen this option working? Am I missing something?

Cheers,

Bogumil

[tomczak]

One trick to try is to extend slightly the white and black point in the Dynamic range slider (below 0% and above 100%), with the 'show clipped pixels' on. You have to be careful in interpreting histograms then as they will include flipped/clipped pixels.

[bogumil]

Well, that is exactly what I did. In fact I have extended the white point to 100% and I could see the sky was blown white. Then I switched the "Show clipped pixels" option back and forth and as far as I could tell the preview stayed the same, i.e. the sky was blinding white with no sign of inversing any clipped pixels.

[tomczak]

To see blown highlights, extend the white point slightly beyond 100% (say, 101%, or whatever the closest higher step is). If your colour model is HSV, the clipped pixels are those that will have at least one RGB channel clipped. In HSL, only pure white will be considered clipped.

[bogumil]

Maciej,

Thanks for the explanations. It's my mistake. After carefully reading once again your post I have understood that you're talking about Dynamic Range and I have been using the Highlights slider all the time. "Show clipped pixels" option works fine when Dyn. range is set to more than 100%.
So if I understand things correctly, using highlights setting does not cause pixels to be blown event though they become 100% white at the far edge of the histogram. They are still within the histogram, right?
So to see if my Highlights setting has done any damage to the picture and in what areas I think I have to set Dyn. range slightly over 100% after making my higlights setting so that the pixels at the far right of the histogram are set out of range.

[tomczak]

Kiril or Jonathan can likely answer it better, but as I take it, it doesn't matter what you adjust in RAW dialog and in what order - the Raw histograms predict what the distribution of pixels values will be in the developed RAW (though it skips demosaicking - so there may be some slight difference between the preview histograms and the histograms of the output image). Interpretation depends on HSL/HSV choice. For instance, if there is a high peak at the 255, you will have maxed-out pixels in the developed image (eiter in at least one channel (HSV), or in all three RGB channels (HSL)).

[tomczak]

Just a thought on showing clipped pixels. I find mapping pixels clipped in HSV/HSL extremely helpful in almost any transformation, especially as I adjust the settings. Though it can already be done in RAW, Levels&colour, using colour ranges in masks, or in high contast - but it's not that overly easy or obvious and in many cases must be done after the adjustments were already made rather then to guide them.

Would it make sense to have the ability to quckly and easily show clipped pixels globally somehow, so that it could be available to most transformations (e.g. having it as part of preview window, or have keybord combination switch or a toolbar button that would colour or flip the min/maxed out pixels either in preview window only or even all windows - kind of like Monitor Curves settings affects all windows globally - this way one could compare a transformation input window and it's preview window and see how much and where the clippings were caused by this particular transformation settings?).

Cheers!

[JML]

Maciej:

About a year ago, I suggested a dynamic clipping display tied to the Preview screen and still think it would be highly useful. Color coding can show the channel(s) maxed out in highlights or at zero in the shadows. I would use it all the time setting BP/WPs in curves and in sharpening transformations. One of the great advantages of a dynamic clipping display over a histogram, is that we can see spatially in the image where channels hit the endpoints. As just one example, a dynamic clipping display allows one to more precisely bypass specular areas when setting a WP.

[tomczak]

Just to supprot this point: the new Monochrome channel mixer has 'clipping' warning that pretty much works this way - no need to to go 'over board...' or do some other fancies. Flipping W<-->B pixels works ok, but it's sometimes hard to see: would it be useful to have them more pronounced/coloured - maybe make the rest B&W at the same time...? It's really helplul to know where the histogram ends hit in space. Cheers!