Are you having troubles distinguishing between red and green or yellow and blue?
Then Chromoculus is the app for you:
It displays the live camera image on your mobile device while processing the critical colors so you can easily distinguish them. Now, you can see previously unrecognizable items and e.g. read red texts on a green background.
There are two modi:
In automatic mode, the colors indistinguishable to you flash in the camera image. Thus, you can see at a glance whether you have missed something important. In manual mode you can determine the intensity of the color adjustment yourself for enhanced readability.
Currently, red-green and blue-yellow color perception problems are supported.
If you prefer your app without adds, you can buy the add-free version in this app store with some additional features: color-specifications, a flashlight and a switch between front and back camera.