At last night's performance, the venue used dim, magenta lighting on the stage that made poor Lauren O'Connell look like a pink ghost. Here's one image exactly as it came out of my camera:
Fortunately, I shoot raw photos, which take up lots of room (about 22 MB each) but with the benefit of lots of uncompressed image information. It's therefore relatively easy, using Adobe Lightroom, to correct for it. Magenta lights are pretty grim, though; the only reasonable correction was to make it black and white:
Had I shot these as JPEGs, the correction would have been almost impossible. The raw format stores light in four layers, much like physical film does. JPEG compression "develops" it all together.
Plus, I have my camera set to interpolate a black frame under an exposed frame when shooting above ISO 1600. (This photo was shot at ISO 12,800.) That gives the processing software even more information to help produce a usable image from horrible conditions.