Ever take a shot and then later think "I wish the light had been this way or that way?" It happens to me a lot, especially outside the studio where I have little control over the ambient light. Here is a fix that works wonders I thought I'd share with 60,000 of my closest friends. It's a method that does not destroy pixels and can be surprisingly forgiving.

We'll begin with this image, though practically any image can benefit from this technique in some amount:

Now, knowing that the human eye will naturally be drawn to the brightest parts of an image, I want to use that to my advantage. I want the eye to first find the horse's head, then follow to the cart behind it, and I don't want the eye to trail off to the background. I'll begin my editing with that goal in mind.

Step one is to add a new blank layer over your original layer (ctrl + shift + N).

Next, set your paintbrush to pure white and 100% opacity. Using the paintbrush tool, paint over your image where you think you want to add more light and/or highlights. It will look ridiculous, but don't worry, and don't worry about being tooooo precise either - as I mentioned, this technique is very forgiving.

You should have something that looks a bit like this:

Silly, huh? :)

Now set your paintbrush to pure black and 100% opacity and paint over the areas you want to darken - again no need to be tedious about it. Something like this:

Now for some magic... with your goofy looking layer selected, change the Blending mode to Soft Light.

The image will still look dumb, don't worry:

Finally, choose Filter / Blur / Gaussian Blur and with a HEAVY hand blur the layer until your shadows and highlights blend seamlessly into your image:

And your image should look something like this:

Note: I added contrast and tweaked levels for the final image.

Before and after comparison:

Note: You may want to do your Light and Dark adjustments on separate layers for more control. You can adjust the opacity of your Light and Dark layers to get precisely the look you want. You can repeat the above steps again and again on the same image until you get the results you want. You can also play with colors instead of black and white for different effects.

Let's have a quick look at using the same technique on a portrait:

Here is my starting image -- it was shot on an overcast day and the light was flat:

Light and dark areas added:

Note: I added light area on the forehead, bridge of the nose, just under the eyes and the chin -- all places where sunlight would normally hit.

Blending mode changed to Soft Light and Gaussian Blur added:

And finally a bit of curves adjustment and sharpening for the finished portrait:

Before and after comparison:

Play around with it - see what you can do! :)