This sounds like what would happen if the programmer incorrectly set the opaque flag on the UIImageView and failed to set its background color to that of the page. Oops.
The EPUB spec requires you to support the image formats, and it does not explicitly exclude transparency, so I would say supporting image transparency is a required part of the spec. Out of curiosity, though, why don't you just fill those areas in the image with the right color?
Also, does this fail with ADE on the desktop, or just Bluefire? I don't think any of the ADE-compatible readers in iOS actually use the ADE rendering code; they all render content differently from one another, and the rendering barely resembles ADE on other platforms.
Last edited by dgatwood; 12-31-2012 at 10:56 AM.