The PDF format is one of the most common eBook types that you are likely to come across on the Internet. While OS X supports the reading of PDF files using the application Preview, and Apple’s portable devices now have
f you're going to use widths in pixels, do remember that the default
target-resolution for PDF is 72dpi, which may or may not match the
resolution of your image. Recalculating the px-widths into something
more absolute is recommended for predictable results.