  Document image has been the area of research for a couple of decades because
of its potential application in the area of text recognition, line recognition
or any other shape recognition from the image. For most of these purposes
binarization of image becomes mandatory as far as recognition is concerned.
Throughout couple decades standard algorithms have already been developed for
this purpose. Some of these algorithms are applicable to degraded image also.
Our objective behind this work is to study the existing techniques, compare
them in view of advantages and disadvantages and modify some of these
algorithms to optimize time or performance.
