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

alt text

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.

alt text

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).

alt text

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?


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.

  • @Matt...and I agree, for hard core toning local adjustments are where its at. Darkroom basics. – Rob Clement Oct 12 '10 at 19:54

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.

alt text

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.

alt text

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.

alt text

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.

  • 2
    There's nothing you can do in levels that you can't do with curves, however there's plenty you can do in curves that's not possible in levels. Also setting the output levels to 7 results in "7" being the darkest colour in the image. Reducing contrast. Coupled with setting the input levels to "8" that is clipping the backs and throwing away data (and thus detail!) so I'm not sure what you're trying to acheive. – Matt Grum Oct 12 '10 at 9:34
  • @matt...that's not what I was told by an instructor who beta tests for Adobe. His take is that levels and curves operate off of different engines. I know PS has an integrated "levels" option in the curves palette now, but the integrated levels, as I understand, is not the same as "Levels" by itself. As for output adjustments, I'm giving an option to safeguard the low end so that detail is not lost. Input at 8 does not go far enough to clip the blacks (so far as the eye can tell), and is in place to increase contrast. – Rob Clement Oct 12 '10 at 19:52
  • It's possible the calculations are done differently between the tools so you might get rounding errors but in principal levels is a superset of the levels functionality. – Matt Grum Oct 13 '10 at 19:39
  • 1
    As for your use of the levels tool... setting input to 8 may not clip any detail if the darkest pixel is value 8, in which case the histogram is stretched making the darkest pixels are value 0 as they should be. But then you adjust the output levels mapping the 0s back to 7s, getting to pretty much where you started from! The only extra apparent detail is from the noise you added. – Matt Grum Oct 13 '10 at 19:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.