Olympus OM-D E-M5

The only way to check if no post-processing took place, is to look in the EXIF data of the picture. There a signature is found of the post-processing software. If you shoot in RAW, your picture will always have this signature and I can not tell the difference. But since many contestants has violate this rule, I would say: just ignore it. I won't DQ no one for this.