Pre-processing stage involves all of the operations to
produce a clean character image, so that it can be used
directly and efficiently by the feature extraction stage.
Before extracting the features from an image, a sequence of
simple, common pre-processing is applied in order to
standardize the data and make it feasible to the recognition
algorithms and to reduce complexity [3].
This pre-processing stage only involves of a thinning
process. Thinning is an important pre-processing step in
OCR. The purpose of thinning is to delete redundant
information and at the same time retain the characteristic
features of the image. Thinning is applied to find a skeleton
of a character. Skeleton is an output of thinning process.
The resulting skeleton images of the characters are shown in
“Fig. 2”.