SnapSeed is a great little iOS photo editing app. Along with brightness and contrast, it has the ability to alter "ambiance" which does a great job of lightening up shadows while still keeping a nice deep black.
Does anyone know the best way to achieve this using Photoshop? Would it be through the use of curves? Or perhaps adjusting the contrast of just mid-tones or something?
Using my motorbike as an example. Before...
and After...
(You can open the images in separate tabs and switch between them for a better comparison.)
Notice how the shadows in the top-left are a bit brighter, colours are perhaps slightly warmer, but black is still black and highlights are not blown out.