Como cambiar un color específico en una foto

Siguiendo con los artículos relacionados con la fotografía y sus colores, traigo nuevamente desde Lifehacker, éste tutorial para la post-producción. Incluye video y desarrolla brevemente una forma sencilla o un modo más avanzado para lograr los resultados deseados.

How to Change a Specific Color in a Photo

We've talked a lot about getting great color our of your photos, but if you don't like the color you have you're not necessarily stuck with it. Here are two ways to change the color of anything in your photo.
The video above describes two techniques for changing color in your photos with Photoshop. The first involves using the color replacement tool/brush to effectively paint on a new color, and the second involves the more complicated method of manually selecting the object and manipulating its light and color values.

 

 

 Using the Color Replacement Tool

The color replacement tool hides underneath the traditional brush in Photoshop. It's the easiest way to replace a color in a photo, so when it works it's definitely the best way to go. All you have to do is select the color you want and paint over the color you want to replace.
 

One of the neat features of the color replacement tool is edge detection, so you can paint more freely without worrying about coloring outside the lines. However, if your brush is too big you're going to find that Photoshop gets pretty strict about the edges. Using a big brush to fill in the large areas is fine, but then reduce the size of your brush to finish off the edges.
That's all there is to it. When it works, it's that easy.
 

Doing It the Hard Way

When it doesn't work you end up with extremely unrealistic color like the blue eye you see to the left. Yikes. To avoid this sort of thing and get a more realistic look I like to take a much more manual approach.
 

I love the polygonal lasso—it's awesome. I use it for most of my selection needs. For selecting a rough shape like an eye, it works very well. You can find it hiding beneath the regular lasso in the toolbar.
 

Use it to select both eyes and then copy and paste that selection into a new layer. Now we've got the original eye color in its own layer. Desaturate the layer (Mac: Command+Shift+U / Windows: Control+Shift+U) and, if you want, auto tone it (Mac: Command+Shift+L / Windows: Command+Shift+L) to brighten things up a bit (we'll be more precise later).

Make a new (empty) layer and select the eyes again (command/control + click the layer). Use the paint can tool to fill in a mild blue and then set the blending mode of the layer to Color. It'll be a little intense so reduce the opacity significantly. Anywhere between 10-20% should be pretty good.
Now go back to the eye layer (not the color layer we were just working with—the one below it) and open Curves. If you just pull the curve up a bit you should be able to brighten things up nicely. You'll see the blue color pop more—but realistically so—now that the dark eye isn't so dark. When you get it to a place you want it, you're all done. Just make sure you zoom out so you know the effect actually works from a distance as well.

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That's it! Got any good color changing tips? Share 'em in the comments.
Send an email to Adam Dachis, the author of this post, at adachis@lifehacker.com.
Fuente: http://lifehacker.com/5630880/how-to-change-color-in-a-photo