Levels and Curves adjustments layers in Photoshop are a staple tool for any photographer who uses the software, but they aren't particularly intuitive to beginners. Here, PHLEARN give a beginner's guide to using both levels and curves.
Curves and Levels are similar adjustment layer tools, albeit not identical. Many years ago I learned Curves first, and as a result I habitually gravitate towards that over Levels, though as Aaron Nace points out, there isn't usually a correct choice here. Initially I wanted to add subtle S-curve to my images for a bit of contrast and was shown how to do so — this will really highlight my age — by a magazine I was subscribed to at the time. (Yes, a physical, flop through your letter box, tangible magazine.) Most of my traditional training in Photoshop had been in web and graphic design, so while I could do a lot of things in the software, much of it was obscure and not applicable to photography.
One elementary function of both Curves and Levels adjustment layers eluded me for many years and I'm glad Nace picks it out to talk about in this video: using the eyedropper tools to set the white, gray, and black points in your image. If you shoot black and white images much — and I wrote an article on this earlier today — this can correct your exposure and contrast with precision. It works brilliantly with color too, of course, but I've always found value in ensuring my black and white photography is at its best with Curves in this way.
Do you have any tips for Levels and Curves adjustment layers you can share?