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 on both SD and HD models. However, without creating multi-rendition articles, 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.
By creating multi-rendition articles, you can create a single 1024x768 folio with PDF articles that look great and perform well on both SD and HD iPads. When you create an article with a PDF image format, the PDF images now have a higher resolution than in previous versions (as high as 108 ppi instead of 72 ppi). While a multi-rendition article looks good on the iPhone 5, the content is letterboxed. For best results, create a separate 1136x640 rendition.
This feature applies only to iOS apps. For Android and Windows apps, content in any article format is scaled up or down and letterboxed as needed.
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: