How to enable OCR with Scangear MP under Linux for MG8250?

Question

Under Linux openSUSE 12.3 I use Scangear MP 1.80 for my Canon PIXMA MG8250.
As a scan target (in my German GUI it's "Ziel") I can choose "OCR". But there is no text output, the scan is just saved as a picture. How can I configure Scangear to open the scan via Tesseract in a text editor.
By the way, the target "Print" (in German "Drucken") leads to saving just as well, though there is at least one printer at hand, of course.
It's a pity that the pixma scan drivers that are shipped with openSUSE don't work with xsane (the scanner starts working, but stops after one third of the page). Using xsane with a different scanner I can use OCR successfully.
Volker

Answer 1

There are two basic types of core OCR algorithm, which may produce a ranked list of candidate characters.
Matrix matching involves comparing an image to a stored glyph on a pixel-by-pixel basis; it is also known as "pattern matching" or "pattern recognition". This relies on the input glyph being correctly isolated from the rest of the image, and on the stored glyph being in a similar font and at the same scale. This technique works best with typewritten text and does not work well when new fonts are encountered. This is the technique the early physical photocell-based OCR implemented, rather directly.
Feature extraction decomposes glyphs into "features" like lines, closed loops, line direction, and line intersections. These are compared with an abstract vector-like representation of a character, which might reduce to one or more glyph prototypes. General techniques of feature detection in computer vision are applicable to this type of OCR, which is commonly seen in "intelligent" handwriting recognition and indeed most modern OCR software. Nearest neighbour classifiers such as the k-nearest neighbors algorithm are used to compare image features with stored glyph features and choose the nearest match.
Software such as Cuneiform and Tesseract use a two-pass approach to character recognition. The second pass is known as "adaptive recognition" and uses the letter shapes recognized with high confidence on the first pass to better recognize the remaining letters on the second pass. This is advantageous for unusual fonts or low-quality scans where the font is distorted.
So I wonder which kind of OCR algorithm are you using?