To a computer, a photo of your CV is just coloured dots — there are no words in it to copy or search. OCR software finds the areas that contain text, recognises each character and rebuilds the lines and words. Good OCR engines also straighten tilted pages, cope with different fonts and support several languages, since accents and special letters — such as Turkish ç, ğ, ı and ş — need the right language data to be read correctly.
OCR is the first step whenever a CV arrives as an image; resume parsing then works out what the text means.
