|
PDF is not a valid ebook format, although it is most likely the most predominant ebook format.
The problem with PDF is that it is a rendering format, showing the content at one fixed page size. If the ereader display is smaller than the fixed page size, either the document is scaled or a viewport onto the document must be displayed... and neither option is optimal. Nearly all PDF ebooks are formatted for a page size that doesn't conveniently display on typical devices such as mobile phones or dedicated ereaders like the Kindle or Sony. And, because PDF is inherently an image format (scalable vectors), it is hard to convert to text while saving document formatting, as witnessed by the bad job most PDF-to-HTML converters do.
Hypertext, in all its variants, e.g., HTML, .MOBI, Kindle's .AZW, etc., is a display format, allowing the content to flow to fit variable page sizes or changing font sizes. A full 'page' depends on a combination of the font size and display size. Because hypertext is based upon textual data (instead of scalable vectors), it is easy to adjust the layout for difference screen and font sizes.
I'm sure someone is working on the perfect PDF-to-hypertext converter... and it will make them a lot of money.
|