Here’s a trick you can do with the free Photoshop filter Mike and Kael’s Kill White (which is an awesome filter for several reasons).

So I have a picture of a flower.  Nothing special.  There’s not a whole lot of contrast and it’s just kind of blah.  I tried playing with the contrast and the colors and I just wasn’t happy with it.  So, I went back to the beginning and did a trick with Kill White instead.

Here’s the original:

I copied the layer.

And converted it to black and white.  That’s Image->Adjustments->Black & White.  I played with the filters until I came up with one that made mostly the leaves darker, but the petals stayed bright.  This time it was the High Contrast Red Filter, but if none of the pre-sets look quite right, you can manually adjust the filter.

Now you have two layers.  A black and white and a color.  Here’s where I use the handy-dandy kill white filter on the black and white layer.  That transformed all the white in the layer to transparent and you get this:

Almost there, but just a bit too dark.  So I adjust the vibrance of the bottom layer.  That’s Image->Adjustments->Vibrance.  In this case I upped the vibrance and the saturation by 10.  Then I upped the brightness by 40 under Image->Adjustments->Brightness/Contrast.  Then I adjusted the transparency of the top layer to 80%.  And came up with this:

Okay, so maybe not an award-winning photo, but it’s a heck of a lot better than the original.

See what I mean?

Cropping helps.

The reason this works is with the transparent and black overlay, I can up the brightness and saturation of the colors I want without losing the nice dark shadows of the parts I want in shadow.  It’s a very targeted way to up the contrast on a photo.