You can change the image categories used in AdBlock Premium's Image Swap feature via the Options page. Open your AdBlock menu in the upper right-hand corner of your browser, and select the gear icon. Under Premium, select Image Swap. You can choose between cats, dogs, landscapes, goats, oceans, food, birds, or your own custom image collection.
Select as many image categories as you'd like, or deselect all categories to turn Image Swap off. Your selections are saved automatically. Just close the options page when you're done.