I'm trying to build a CNN to identify whether or not a picture contains a lion. One of my classes would obviously be filled with pictures of lions, and pictures that have lions.
What about the data I put in my not_lion class? Should I fill it with images of random things (for example, take a few images from each class in ImageNet)? Should I put in pictures of things similar to lions, like tigers, so the network better learns what a lion actually is?
My idea is to make 50% of the not_lion class pictures of tigers, pumas, etc, and 50% random stuff - I think that this would make the network learn what a lion actually is, and also ensure the network doesn't classify a laptop as a lion.