Book covers were boring in the Regency; i.e., there weren’t any images on them. But there were lots of images in them. George Cruikshank did a thriving business in black and white etchings for books, notably the novels of Charles Dickens and Laurence Sterne. As you might imagine, color illustrations were prohibitive. In fact, books were pretty expensive, too, which is why private circulating libraries flourished, and why all those rich dukes and earls were the only ones with big libraries. To own a book was a mark of wealth. Thank goodness books are now much more readily available for everyone.