The purpose of this paper is to propose a new multi stage algorithm for the recognition of isolated characters. It was similar work done before using only the center of gravity (This paper is extended version of “A fast recognition system for isolated printed characters using center of gravity”, LAP LAMBERT Academic Publishing 2011, ISBN: 978-38465-0002-6), but here we add using principal axis in order to make the algorithm rotation invariant. In my previous work which is published in LAP LAMBERT, I face a big problem that when the character is rotated I can’t recognize the character. So this adds constrain on the document to be well oriented but here I use the principal axis in order to unify the orientation of the character set and the characters in the scanned document. The algorithm can be applied for any isolated character such as Latin, Chinese, Japanese, and Arabic characters but it has been applied in this paper for Arabic characters. The approach uses normalized and isolated characters of the same size and extracts an image signature based on the center of gravity of the character after making the character principal axis vertical, and then the system compares these values to a set of signatures for typical characters of the set. The system then provides the closeness of match to all other characters in the set.
 T. Nawaz, S. A. H. S. Naqvi, H. Rehman and A. Faiz, “Optical Character Recognition System for Urdu (Naskh Font) Using Pattern Matching Technique,” International Journal of Image Processing, Vol. 3, No. 3, 2009, pp. 92104.
 M. Al-A’ali and J. Ahmed, “Optical Character Recognition System for Arabic Text Using Cursive Mutli-Directional Approach”, Journal of Computer Science, Vol. 3, No. 7, 2007, pp. 549-555.