PixArtCam

You can select photos for processing from your device's camera roll or take a picture with the app's camera.
Pixel size can be increased or decreased.
You can increase or decrease the number of colors. This allows you to make photos look like they were taken with an old mobile phone camera.
It can also be monotone.
Processed photos can be saved to the device's camera roll.
You can also share the information to social networking sites via the share button.