Image preprocessing of images clicked from camera

[s4re...@gmail.com]

I have to recognize text from images. 

The problem I am facing are:

1. sometimes the text background and the text itself vary slight in terms of pixel values when grayscale is applied. Like if my text is light blue and the background is dark blue.

2. How can I binarize such that I only have black and white image with text in black and rest white ?