I have a photo that is underexposed by probably two stops (and maybe even three). If I could improve by even one stop, it would be great. I can see individual faces (a family gathering), but it’s still pretty dark.
Anyone with any experience???
(I’m not quite ready to fork out a ton of money for Photoshop–just wanting to know if it can help.)
It’s hard to recover detail that just plain isn’t there, but it’s surprising what you can do.
Generally, you want to break it into at least two layers and adjust them individually. (ie; brightening the dark areas and adjusting the contrast for them will be a sledgehammer adjustment that would wash out all the detail in the faces and other bright areas – so you mask those areas off and adjust them seperately.)
If you’d like me to give it a shot, you can send the pic to daledibbley@hotmail.com – I should be able to do it either late tonight or sometime during the day tomorrow.
If you have any control over it, try to send it as big as you can, and with the lowest (ie highest quality) compression you have available. If you can post a bitmap somewhere, that’s even better. An underexposed picture will be have a lot of low-contrast areas that will look ugly as sin if they’re corrected after a major compression, requiring a lot of manual touch up. Those .jpeg cheats will stand out like you wouldn’t believe when you take them out of the shadows. 
Try doing a gamma correction. That’s what I do to improperly exposed/developed pictures in other software.
For Photoshop, try the Image->Adjust->Curves mod.
Yes, you can do this. As others have mentioned.
I frequently underexpose my photos and I usually am able to tweak them into looking decent. I tend to tinker around in Channels sometimes too. And Curves are always good.
At a Photoshop seminar a few years back, the lecturing expert suggested duplicating a layer and merging to get enough light-to-dark range to work with. Haven’t tried it, but it sounds plausable.
I have a spare install CD of Photoshop Elements (A stripped-down version of photoshop that lacks some of the advanced features, but apparently, you can get some of them back by means of plug-ins, which it does support). If you’d like it, it’s yours - just email me at TheMangetout (at) Hotmail (dot) com and tell me the full address (as I’d be, airmailing from the UK) to which you’d like it sent.
A program called ACD see lets you adjust gamma, blackpoint and whitepoint. I haven’t used PS in a while, but look for similar features. Contrast and Brightness help a bit, but the bulk of the benefit will come fom using gamma, blackpoint and whitepoint controls.
I’ve done a lot of imaginf stuff, and exposing an underexposed photo with this has always amazed me.
Send me the pic and I’ll be glad to try my hand at it.
If you’re just starting out with Photoshop, you can do a lot with Levels. There is a white point dropper and a black point dropper to the right of the Levels window - click the white point dropper then click on the whitest point of the picture, then repeat with the black point dropper on the blackest part of the image. (To more accurately find the white/black point levels, you can click on the Layer Effects button on the bottom of the Layers window and select Threshold. Move the slider back and forth, and you can see where the lightest and darkest points end up. Discard the Layer effect after you get the information you want.)