Hi there,
Unfortunately, that's out of our hands. Amazon resize and recompress all epub graphics uploaded to them and don't provide a way for companies to override their algorithms if there's a problem. They also don't provide a specification sheet which would allow us to submit a version which we know works.
I'm really sorry. The best I can tell you is to ask Amazon for a refund because they screwed up the book after uploading and then buy it from any of our other partner stores (Kobo, Apple Store, Google Play, Bookwalker) as none of them manipulate the images. Comixology does have some magic process which they run as well, but given that their platform is designed around the needs of graphic novels and comic art, the image quality will be non-deteriorated and our books are configured to work with Guided View.