I convert books to epub from InDesign CS5.5; as I have already the JPG cover (800 x 600 px; 100 KB) on the first page of the book, I choose "Rasterise First Page" from the conversion menu; I then unzip the to and examine the files; I notice that, in addition to the JPG cover image, the conversion has created a 1MB PNG file of the same image. I tried to delete the PNG file (and removed its reference in "Content.opf"), but no cover then appears as a thumbnail on my iPad library (although the cover appears on the first page of the book, when I open it); so it seems that the PNG file is only used for the thumbnail view in the library.
Whatever I tried, I couldn't get the epub to use the JPG file for the thumbnail view (including trying "No Cover Image" and "Use Existing Image File" in InDesign).
How can I get the epub to use the same file for the thumbnail, as well as for inside the file (when you open it); I wouldn't have minded if the PNG file wasn't so big (ten times the JPG file of the same image). Am I doing something wrong or is it a bug within InDesign?
Please help. Thanks
Create the cover at 600x860 and use the “use existing image file” option.