Thanks Dave.
It's just something I read about, I think, in a photography magazine or in one of my books. What it is, is an alternative to curves, levels, contrast/brightness, exposure, and a myriad of other avenues within PSCS2 used to change the relationship between lighter and darker areas of the image. Two main advantages of a gradient include 1) not only can you vary the opacity of the gradient layer, but you can use the eraser tool to expose the primary background layer under the gradient, and 2) it's a neat way to deal with the fact that very often there's a light fall-off within the scene and you wind up with something like, lets say, a too bright foreground but a nicely exposed background. On top of that let's say there's too much yellow throughout the whole picture. You could set up a gradient from dark blue to light blue (you could choose another color - whatever you think will counteract the yellow). Place the cursor where you want to introduce the dark blue (to tone down the brightness of the too yellow foreground) and extend the gradient in the direction you want, towards the area where you got the light blue from. (Naturally you're doing all of this in a new, transparent layer) Then adjust the opacity of the layer overall to darken the foreground but leave the background more or less unaffected in terms of exposure, erase here and there as needed and fine tune in any other way you might care to so that the blue tint of the gradient mellows out the yellow overall and also darkens the foreground. The gradient tool has a lot of flexibility just like all the tools in photoshop so really it's uses are endless.
I hope that's not too confusing. The gradient tool is discussed in the Adobe PS manual, all the after-market books about photoshop, in magazines and on forums. So this is not some cowboy deal I made up on my own.
The thing about it is that the other tools I mentioned above work so well, you might not have much occasion to use this gradient technique. I use it every now and again though. It may or may not be any better than other techniques - but it did work well for me here because the image was divided evenly into large areas I wanted to modify.
Man, photoshop is deep!
