Dropbox have make a blog post about there automatic enhancement method for scanned document image - Fast Document Rectification and Enhancement.
I followed the post and they mention a formula to make ...
OCR works best for black on white or binary images, where letters have sharp contours, no noise, and solid filling, i.e. they are nothing like this:
For the curious it's a part of a document number ...
For those who have either used Picasa/Photoshop, they would see different image enhancement options such as:
I have searched online a ...