Originally Posted by thomass
The app needs to convert the pages into images in order to do this process. Therefore you need to do an OCR (with ABBYY, etc) on the output file to be able to highlight, etc.
Thomass is correct that k2pdfopt converts to images, so no highlighting can be done. I am hoping to add OCR capability to k2pdfopt soon (via Google's Tesseract engine). I have a test version working on English text. I haven't been able to find as much programming time as I've wanted to this summer, but eventually I'll get it released.