EPUB -> PDF: Image Rather Than Text
I've only been using calibre a few hours, so please bear with me if my questions seem obvious...
Background: I have my technical library in PDF files. I use Foxit Reader to read, highlight, and annotate my books. In order to highlight, the PDF files must contain embedded text, as opposed to an image of text. Sometimes desired books are not available in PDF, only EPUB. I'm seeking to use calibre to make the necessary conversion.
As a start, I converted the calibre Quick Start Guide EPUB. After tweaking the conversion preferences, I got a functional PDF. I obviously have much to learn, but so far, so good.
However, when I convert a technical book EPUB with the same preferences, I encounter an odd problem. The resulting PDF appears to be mostly an image, rather than embedded text. Only certain types of headings or mono-spaced fonts are converted to text. The remainder of the content appears to convert to an image of text, rather than actual text.
I've looked at the Debug dump. The OEBPS HTML files in the input, parsed, structure, and processed directories all clearly have the content text intact. Yet, the converted PDF appears to be almost completely an image.
The only possible clue I see is that the technical book EPUB includes several OTF font files. The calibre Quick Start Guide EPUB does not. Outside of that, I'm lost as to why I get such drastically different results from the same conversion preferences.
Any suggestions are greatly appreciated...