[thiago.eec]

Originally Posted by jhowell

The Amazon Kindle Publishing Guidelines explicitly state that image transparency is not supported, even though it does work in many cases.

You are right. Its very clear. But it does work when I use AZW3 (converted by Calibre) or MOBI (produced by Kindle Previewer). And, funny enough, those formats retain the original GIF, with its transparency, as I could check using KindleUnpack plugin.

Originally Posted by jhowell

When producing KFX format the Kindle Previewer converts all images to JPEG format causing transparency to be lost. You cannot prevent this.

Like I said above, Kindle Previewer is not converting GIF to JPEG.
Also, according to the guide you pointed out (item 9.4.1 - Use Supported Input Formats), GIFs are supported for Enhanced Typesetting (KFX, right?). It only states that multi-frame GIFs are unsupported.

Originally Posted by jhowell

The transparent background should be made white in the process, not gray. That is the case when I convert the modified Frankenstein book that you attached earlier in this thread.

If you attach your sample that instead shows a gray background when sideloaded then I will try to determine why it is not working as expected. I was able to reproduce the problem using the book you uploaded previously and I am looking into it.

Thank you!

Originally Posted by jhowell

I believe that the exported MOBI will contain the original GIF images with transparency, but it is not guaranteed to render properly on all Kindle apps/devices.

Yes. Indeed, both the MOBI exported and the AZW3, retain the original GIF, as I said above.