Normal processing of digital image RAW files is acceptable and must reflect the natural color, light, and contrast at the time of exposure.
Any digital manipulation beyond levels, curves, color balance, contrast and brightness must be fully disclosed, including, but not limited to: cropping, digital stitching, cloning, airbrushing of any kind, alterations made to a scene to add or remove elements, etc.
Discovery of undisclosed digital manipulation will be grounds for removing a submission from further consideration.