From PinataIsland.info, the Viva Piñata wiki
Once unlocked, concept art can be viewed in your Journal, by selecting Player Awards, then Photo Albums, then Bonus Photos.
Ways to unlock concept art
- Repeatedly take photos of one of the listed species or characters until its bonus photo appears. It may take 10 or 20 photos.
- Scan one of the concept art Piñata Vision cards.