Last year I was a little annoyed that Photoshop didn't have a "click on white to white balance the picture" function. So I wrote this little script to do just that. I figured someone else out there might have some use for this too.
All you do is use your eye dropper to select a color that should be white to make it the foreground color, then play the script. It will give you a few parameters to adjust so you can fine tune your color adjustment, and tah-dah, you have yourself a white balanced image.
A few things to note:
1) It applies the white balance to the layer that is selected, not the entire image.
2) It saves a new layer, so it is completely non-destructive.
3) I wrote this for Photoshop CS2. I would assume that it works for CS3 and CS1, but I've never tried. I knowthat it doesn't work for 7.0. I did make a 7.0 version though, so if anybody wants that one, let me know and I will try to dig it up. I'm pretty sure it didn't have as many options.
4) It has a black balance option too. Click on something that is supposed to be black and make that color the background color. I have never actually used this with good results, but it's there in case your picture has really messed up shadows.
5) It actually works pretty well. If your colors are way off, then it's probably better to fix it by hand. I think having the intensity and the threshold options are pretty handy, being that I generally don't want my whites to actually be pure white.
1) If you have more than one layer selected, it is going to screw stuff up. It won't mess up your picture, but it will create a bunch of layers and the white balance won't work.
2) Mac users, it works just the same, but you don't get to preview the changes you are making when the dialog is open. I suggest unchecking the "merge to single layer" option and just adjusting the opacity of each layer that the script creates. This is the same adjustment that the "Intensity" knob adjusts.
These are the only issues I know of. If you find other problems, let me know, and I will most likely do nothing about it.
How to run:
Just stick it in your Adobe\Adobe Photoshop CS2\Presets\Scripts folder. Next time you open up Photoshop, it will be under File->Scripts.
Enjoy and let me know what you think.
White Balance CS2.jsx - you'll want to right click and save as or it will just open up the code in a new window.