Here's how to create this effect.
First, make your letters as you normally would, with a text tool. You can make them any color you wish.
Next, simplify those letters so they are now a graphic representation of the letters. That is, they are no longer editable letters any more. They are now a graphic that just happens to be in the shape of letters. In Photoshop you do that by clicking on the layer in the layer navigation area and clicking on simplify.
Select a section of one letter. Now do select - similar to have it select all of the letters.
With those areas of the screen selected, use your layer navigation window to select the layer that has your image on it. In this case I chose the layer that has my kayak-on-lake scene.
Select COPY. You now have a letter-shaped section of that image in your clipboard.
Voila! You now have letters created out of that background! Slide the layer so it's on top of the other ones. You can now play with the hue, saturation, lightness, and other aspects of the letters to get the effect you're after. Want them lighter? Darker? The choice is yours!
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