Publishers face a challenge in that iPads and iPhones include both SD (Standard Definition) and HD (High Definition) models. One approach is to create a single folio that works in all models. However, some content appears pixelated on the HD device, and some overlays behave differently. Another approach is to create different renditions for both the SD and HD models. However, renditions are somewhat difficult to maintain for some publishers, and single-issue apps do not support multiple folio renditions.
With the v23 release and later, you can create a single 1024x768 folio (v23 or later only) with PDF articles that look great and perform well on both SD and HD iOS models. When you create an article with a PDF image format, the PDF images now have a higher resolution than in previous versions (108 ppi instead of 72). While a multi-rendition article looks good on the iPhone 5, the content is letterboxed. For best results, create a separate 1136x640 rendition.
Note: If you want to use a resolution higher than 108 ppi for certain images, you can make that image a high-resolution overlay, such as an image sequence with only one image file.
In addition, you can perform the following tasks to create a multi-rendition PDF article: