Thanks to Yoshua Sunjo for sending in this full Photoshop tutorial (w/pictorial) -- Eye Enhancement. Yoshua writes
In this two-step tutorial I'll demonstrate how to enhance eyes while still keeping the eyes realistic in appearance. I'll include some Effects, tips, tricks
The goal of this tutorial is to teach you the quickest and most effective method of enhancing eyes through adjustment layers. This tutorial is for Photoshop. Ideally CS5, but this tutorial should produce identical results for all versions of Photoshop CS and higher.
Step 1: Adjustment Layers
The first thing we'll be doing is selecting a picture to enhance. I've personally decided to use a stock photograph of someone with dark brown eyes to demonstrate that any eye can be enhanced through this technique. Above is the stock image I've used:
First, go to Layer>New Adjustment Layer > Levels... and click 'OK', keeping the default settings.
Next, we're going to fill the layer mask for the Levels layer with black to effectively hide the Levels effect. So hit Ctrl+A on your keyboard to make a selection of the entire canvas, then fill the canvas (layer mask) with black.
Now set the Levels layer blending mode to "Linear Dodge (Add)" (or simply "Linear Dodge" for older versions of Photoshop), and set this layer to 70% Opacity.
Now, with the layer mask for the Levels layer still selected, change your Foreground color to white. (hit D on your keyboard to do this quickly.)
Next, select the Brush tool (or hit B on your keyboard to access it quickly), and choose a soft round brush at around 20-25px depending on the size of the eye in your photo.
Now zoom in and carefully brush around the iris to brighten the eye as demonstrated above:
Note: Make sure to avoid the pupil of the eye, and the outer edges of the iris when brushing. You should now have something like this:
What we did there was add a Levels layer to bring out the details that are hidden in the darker areas of the iris, but only in a specific area; by avoiding the outer edges of the Iris with the layer mask. This is to give the eye a good sense of depth and variation.
Adjustment layers are a great feature in Photoshop that you should always experiment around with when modifying photos, in the next few steps we'll be doing more of the same.
NEXT : Step 2: Layer Masks & more adjustments
... continues on the next page!