Optical Character Recognition: Why?
Graduate school is marked by a tremendous amount of reading. The vast majority of this reading seems to be in the form journal articles or book chapters which - thankfully - are often available electronically. (If they aren't, I often take the time to scan them myself.) I end up reading most of these on my tablet where I want to highlight text and otherwise annotate them. Sometimes, however, one comes across a PDF whose text cannot be selected - and therefore cannot have its text highlighted. The solution for this is to run optical character recognition (OCR) software on the file. While many modern scanners automatically perform OCR as part of the scanning process, I still come across enough scanned documents without select-able text to warrant this post (see Figure 1).
There is considerable variety among the OCR solutions available. MakeUseOf gives its recommendations for three free OCR solutions, but all of them result in a the PDF's text being stored in a separate text document. This is useful if getting access to the raw text is the goal, but it is not sufficient for my purposes: I want the OCR'd text to be stored in the original PDF file in such a way as the text in the original file can be selected and highlighted. There are no doubt commercially available tools to accomplish this task, but I prefer free (and open source) tools whenever possible. Enter WatchOCR.