Working with Unsupported Formats
The only image formats currently supported by the ePublisher Platform are GIF, PNG, and JPG. If you use unsupported by-reference graphics in your source material, or if you have additional graphical elements, such as callouts, annotations, or shapes, then ePublisher will create a new image, rasterized according to the settings in the style designer, and rendered in one of the supported formats.
By default, unsupported images will be rasterized as 24-bit JPG. To change this setting, open the Graphic Styles tab in the Style Designer. Click the Default style (or if one does not exist, create a new Graphic Style called "Default."). On the Option tab, change 'Format,' 'Output file extension,' and any other applicable settings. Then, regenerate output to apply the changes.