I will be reviewing some software design and architecture considerations for developing a robust and scalable digital publications system:
1. Raster v/svector format based documents

Image formats like jpg, gif etc are raster based formats. These formats are better from performance point of view if compared to the raster format document/file of the equivalent file size. However, raster formats shall not resized at runtime, since it will reduce the quality of the document and make it look blurry. Vector format documents like pdf or swf files on the other hand are lightweight and draws itself dynamically at runtime based on the display size.

I recommend using vector documents for digital publications. Vector format documents will draw itself based on screen size and not loose quality.

2. Screen resolution ( and DPI)

Generally, digital publications are generated from PDF files. It is recommended to PDF document of at least 100 DPI for quality publication.

3. Aspect ratio

Aspect ratio is the ratio of width and height dimensions of the document. Digital publication shall dynamically resize the height and width of publication to maintain the original aspect ratio, which is generally the aspect ratio of the PDF document, which is being used to create the publication. If system dynamically adjusts the display based on input documents aspect ratio, then it will work just fine for landscape and portrait documents of any size.

Maximize height or width for the display based on whether the document format is landscape or portrait instead of hardcoding the default dimensions.