The shadow/hilight tool is best if you want to actually brighten the shadow areas. Adjusting the "tonal width" allows you to specify how far in to the midtone range the adjustment will affect. If you actually need a selection of the shadows, try command-clicking on the composite channel (rgb or cmyk), invert the selection and from there you can save it as an alpha channel and adjust levels or curves to cut off the midtones.
No, thanks.
I am trying to noise filter the darker areas, by luminance.
I would select the level of luminance, and everything darker, and then feather my selection, then apply the noise filters.
Select black as the foreground color before opening Color Range…then by default, Color Range will select 0, 0, 0 (black). Then increase fuzziness until you reach up into the deep shadows.
Did you try my second suggestion?
Jeff, clever idea, but the fuzziness is a poor substitute for Luminance Amount.
I did a test with a black-to-white gradient, and setting fuzziness to 200 did NOT give me a clear cut-off, but instead gave an alpha selection fadeout to much higher luminances.
What I really want is to select luminance, say 32, and all darker than that…
PeterK, thanks. I had a play around with your suggestion #2, but I’m not clear on how to get it to work for a particular luminance.
For example, I want to a selection for all luminance areas up to value 32, with a Hard Cutoff. I do not want ANY values above 32 selected at all, and I want all values 32 & below selected 100%.
Thanks
Perhaps clicking the Magic Wand on a deep shadow with Tolerance 16 or 32 / Non contiguous/ would select what you want?
Anne, Thanks.
I did some tests, where I select a black (0,0,0) patch, non-contiguous, then look at the selected pixels with the CMYK readout. Looks like your method works.
I’ll give it a go over the next few days and let you know how well it works.
Re: Camera; No, I have scanned negatives, which is why I have so much noise in the dark areas. We had to push the scan, and overdid it on a few. Two of the worst negs will need re-scanning next week.
THANKS!
William
You could make your channel mask, save it as an alpha channel, then use levels to adjust the extreme end down to whatever darkness level you want, then pull the other end all the way over to meet it and you’ll have a selection that’s fully selected for the part you want, and fully unselected for the part you don’t want. There may be one value in between that’s partially selected but that can easily be removed with a second level adjustment. The only tricky part is figuring 32% of 255 levels, and only if you don’t have a calculator. 🙂
A luminance mask, then treshold for an hard edged selection.
Even better! I rarely use threshold, but it does come in handy from time to time. I’ve mostly used it for identifying the darkest parts of an image to check ink limits, or look for blown-out hilights.
William heres 2 suggestions:
Remember the blend-if sliders (accessible under Blending options) you can avoid making a mask at all. This will allow you to use the luminosity of the underlying image to mask part of a layer.
You can also use a Curves layer set to Luminosity blend – if you are in RGB you can be very specific about which points you want to affect in overall luminance.
I used the "easy" technique:
Non-contiguous Magic Wand, tolerance 40, click-on a Black (0,0,0) area.
Then I feathered 4 pixels, which gave me pretty much what I wanted. On some images, I decreased the tolerance to 25…
Then I used Noise Reduction, Strength 10, Preserve Details 10%, which removed most of the noise from the dark under-exposed, grainy areas of the images.
Thanks.
