OCR
Find text in screenshots using Tesseract open source library.
http://stackoverflow.com/questions/11978986/ocr-getting-text-from-image-using-tesseract-3-0-and-imagemagick-6-6-5
Rotate an scanned image to normal position
http://felix.abecassis.me/2011/10/opencv-rotation-deskewing/
Algorithm to detect text lines in image (like lines of text)
http://www.cvmt.dk/education/teaching/f09/VGIS8/AIP/hough_09gr820.pdf
Tutorial - scan math equation and graph it
http://ayoungprogrammer.blogspot.ca/2013/01/equation-ocr-part-1-using-contours-to.html
Math derivation of "moments" concept
http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/OWENS/LECT2/node3.html
ABBYY cloud OCR web service
iPhone app
http://www.technology-digital.com/smart_phones/abbyy-creates-a-mind-blowing-scanning-app-for-iphone
OpenCV - C library with language bindings for image manipulation and computer vision algorithms