Galaxy S3 camera exposure value can be changed from -2 to +2 (the default EV is 0). In photography, exposure value (EV) denotes all combinations of a camera's shutter speed and relative aperture that yield the same exposure for a given scene luminance (Source: Exposure Value in Wikipedia).
To change the Exposure Value on Galaxy S3, do as follows:
1. Open Camera application
2. Go to Camera's Setting (By tapping the Gear Icon on the top menu)
3. Tap Exposure Value
4. Now change the value to have a more professional photography experience