The Curves tool affects light’s two primary influences: tones and contrast. Tonal curves are also what give different film types their unique character. It can intensify an image and make it more detailed.

Before and After

Step 1
Open up your picture in Photoshop.

Step 2
Go to Layer >> New Adjustment Layer >> Curves. We’re going to be changing the Red Channel first. My settings:

Green Channel

Blue Channel

RGB Channel

Step 3
Click Ok after you have all your settings to what you want.

Step 4
Now to make sure your Layer Palette is out, click F7 and duplicate the Curves layer by right clicking on it and selecting Duplicate Layer.

Step 5
Set that layer to Overlay 25%.