Let me explain you in detail.
Suppose i have number 0304948457575747483322 in text file.
Step-1 :
i want put this number into .pdf file.
when i generate this .pdf file default font is helvetica.
OCR reader will not read this helvetica fonts.
I have to convert this number into OCR font first and then put it in a .pdf file.so OCR reader can read that number.