What's the resolution of the pictures you're using? Perhaps you need better quality (higher resolution) artwork.
Those images look really weird.
They don't seem just low-res, but as if both a posterizing effect and some scarface plugin was applied.
Sorry, no clue how that could have happened, or what the source of those images are, just an observation.
They resemble a bit how low-quality .gifs sometimes look like.
Maybe they are gif? And not jpg or png?