If of interest and maybe for discussion.
Itís about an ACR feature request which Iíve placed in the respective forum over there:http://www.adobeforums.com/webx?14@@.3bb6a85c.3bbc8060/373
This proposal refers to the Recovery slider in ACR.
I would like to have more control(s) with this feature
i.e. Amount, Tonal Width
and maybe Color Correction (saturation)
such as given with the Shadow/Highlights tool in Photoshop.
Background is as follows: ACR is capable to show Ďfullí highlight details when setting almost all sliders of main adjustment tab to zero (except white balance of course) and by choosing an appropriate value for the Exposure slider. Thatís sometimes called a Ďlinear renditioní. Itís not meant to deliver an overall pleasing image, but it can be informative regarding single aspects.
Now, when we raise the main tone curve (resulting from Brightness + Contrast functions) e.g. to standard Brightness 50 + Contrast 25, data are compressed beneath the upper shoulder of this S-curve. Hence, highlight details, contrast as well as saturation are easily getting lost.
The Recovery slider seems to try to undo such damage which already happened earlier in the processing chain. I would assume that itís based on a gradual selection of pixel (or mask) combined with some sort of darkening curve. However, I donít know about its mechanics, and itís not really relevant here.
In practice, I often find that thereís a quite high amount of Recovery needed to regain more or less Ďfullí highlight details (as initially seen with said Ďlinear outputí) which then has a too strong influence down to the midtones. Recovery tends to darken the light midtones as well which is not necessarily desired. So itís easy to run into a back and forth with all other sliders effecting tonality (including the curve tab)Ö
With the S/H tool in Photoshop, the Tonal Width (of selected pixel, as I assume again) can be pulled down to very low values and even to zero Ė which isnít actually zero as the results prove. Together with an appropriate Amount of letís say between 20 to 80%,
highlight recovery in fact stays limited to the highlights. For example the details of white clouds, etc.
My feeling is that such choice of high Amount and low Tonal Width is often preferred to mirror and counteract the roll off and related side effects from a sigmoidal tone curve (needed to compensate for dynamic range compression).
The latter consideration is of course subject to the image content, so Iíd like to keep it flexible with more control(s) as suggested above. <<