Ok. White balance can be simplified as how appropriate colors look. I can get into degrees of color inclinations in light, absolute whites/blacks, etc. but that will be another day. For now, I'll show you with three pictures:
Old picture. Which one looks better to you? Most will say the first picture. Some will prefer the last picture. Hardly anyone will prefer the middle.
The middle picture has it's white balance off. It looks blueish. Photographers call it looking 'cold' (although I will argue that it's actually hot since blue = hotter than red in light).
To correct this, you would add more 'yellow' into the image. In photo editing programs, blue is the opposite of yellow and thus correct each other. I will get into color theory some other day.
In the first picture, the white looks white. It has been corrected. However, it looks dull right?
In the third picture, however, the dress looks yellow. You must remember that sunlight has a natural yellow-green (slight green) tone to it. The third picture looks more natural because when the sunset hits the white veil, it takes on a yellow color. We'll get into atmospheric alterations in sunlight, as well as ground-type bounce color alterations in sunlight later. But this should explain it.
You are often supposed to make the white look as white as possible in white balance correction. Arguably, white balance correction is to portray the natural colors instead. However, in my case, if the veil was looking yellow because of the sunlight, who am I to change nature's beauty?
White balance correction is especially helpful when taking pictures indoors in tugsten lights or hallu lights. They add a 'yellowish' or 'blueish' look to your pictures respectively.
To correct this, you can use photo software like photoshop and 'auto correct' colors. It may not always get it right, however. Even windowslive photo gallery has a way to fix white balance. They call it 'color correction.'
This post was edited by onepagememory on Jun 2 2010 06:15pm