Preserving texture in shadows with levels/curves

Question

I have the following image, and I would like to preserve a little bit of texture in the shadows.

As you can see (hopefully), the darkest parts of the image have gone to a solid black. There is some texture there that I would like to keep; not much, but some, and I would like to bring it out in the final image.

This is already a fairly aggressive rendering of the source file; here is a literal interpretation of the raw file, with autolevels turned off. For reference, here is the .NEF itself.

I am assuming that one does this with the levels or curves tools. Here is a screenshot of the Bibble levels & curves settings for the first image (note that it is also converted to B&W using the iNDA plugin).

I have tried adding additional control points to the curve but quickly became confused as to the mapping between input and output intensity. Perhaps untangling this confusion is the key?

Answer 1

Reid. Don't throw your blacks into the pits of despair! Just don't tone so aggressively. That's the easy answer.

Here's the more involved answer. I'm not sure what your end game is: print, web, tele, all have different sensitivities. But the general approach I would use goes like this. Process your RAW as you have, then hop into PS (I did my best to emulate your approach on the RAW). In PS go...

Layer -> Adjustment Layer -> B&W.

Bring your yellows up and your cyan and blue down to enhance the details of your highlights and shadows respectfully.

Then bust open levels. Yes levels, not curves. We're in B&W land and our focus is 0 and 255. To cut the knees off the detail gobbling black change your Black output to 10 (or so, I did 7) and compress your histogram from there.

Remember that your end Raise your black output by ten points or so. I bumped my black point by 8 for contrast but carefully avoiding undoing the work I just did through output.

You can also add some noise if you like, but that seems counter to preserving and enhancing the cloud's natural details. Hope that helps.

Answer 2

You are right that curves is the way to increase detail at certain brightness levels. The steepness of the line dictates contrast (and hence detail). You only have so much "height" to play with so making the line steeper in one place (e.g. the shadows) means it must be shallower elsewhere. If you're careful you can make the line shallow in an unimportant area (such as where the histogram shows few values, usually at either end) and so get the contrast you need where you need it.

The above used global adjustment (ones that affect the whole image) and is therefore always going to be a compromise (contrast in the shadows means less contrast in the midtones etc.) There is another option, and that is local adjustments. This way you can alter the contrast in certain spatial areas of the image without affecting the others, giving you maximum contrast and detail overall. This is how tonemapping works, which is responsible for the "HDR look". You can get this effect with a single exposure, just Google for "single image HDR". Alternatively you can get a similar effect with the "fill light" slider in Abobe Camera Raw or Lightroom. Finally you can do it old school by masking off the dark areas in Photoshop and altering the contrast with levels/curves.