Note the image with the wolves. I think the entire exercise is in that photo. This system seems very good at patterns. The animals do well when against natural backgrounds. That's because they match those backgrounds. Even though they are different colours, animals with fur all adopt some form of camouflage. So their patterns at some level match the patterns of their natural environment.
The wolves are rendered well, the flowers not. Wolves are camo. Flowers are the opposite. They want to stand out from the background. So the machine doesn't handle them well. The green stripe on the truck also fits this.
To take this idea forward, look at the image of the puppies against the grass. They are not camo. Their colour is the product of breeding, therefore they do not render so well as the wolves. There might be something useful here to measure whether or not an animal is being viewed in its natural environment.
> Wolves are camo. Flowers are the opposite. They want to stand out from the background. So the machine doesn't handle them well.
There is a simpler explanation. Wolves only come in a few different colors. Flowers come in a variety of colors. Therefore, there are only a couple of correct answers for coloring a wolf, but a wide variety of completely incompatible answers for coloring a wolf.
You are right that flowers come in a variety of colors because they want to stand out. But I don't think the neural net understands that. It just knows that a gray flower could be any color while a wolf is confidently going to be some kind of brown.
Ugh. Seriously? Didn't we all discuss literally yesterday about pedantic misinterpretation of text on the Internet?
This article is about colorization, which means taking shades of gray and selecting a hue and saturation for them. The brightness is effectively fixed because, guess what, a black and white image can convey brightness already.
Obviously, black and white coloration on wolves falls outside of this because those are more or less already correct in the black and white image.
Now look at that picture you linked. What do you see? White: doesn't need much coloration. Black: uh, also doesn't need much coloration. Slightly brownish gray: like I said, wolves are all some kind of brown.
Show me a blue wolf, or a green wolf, then we'll have something interesting to talk about. But most wolves, like almost all mammals, have coloration pretty much limited to dull warm colors and tints and shades of those. Here's a picture for you:
The wolves are rendered well, the flowers not. Wolves are camo. Flowers are the opposite. They want to stand out from the background. So the machine doesn't handle them well. The green stripe on the truck also fits this.
To take this idea forward, look at the image of the puppies against the grass. They are not camo. Their colour is the product of breeding, therefore they do not render so well as the wolves. There might be something useful here to measure whether or not an animal is being viewed in its natural environment.