Until now, Google Book Downloader has used the default image resolution provided by Google, even though books.google.com allows you to zoom in on pages to see higher resolution. Version 2.1 fixes this, finding the highest resolution available for every book you download. To download Google Book Downloader, see the app page here.
As you can see, books downloaded with this new version look much better. Now, the technical details:
If you’re interested, this code is all available on Github. It simply adds a few methods to WebKit’s WebView which allow you to find an element in a web page, click on a location in a web page, or click on an element.