Typical OCR software can handle only binary images with black pixels representing text and white pixels representing background.

It isn't unusual in modern documents to have inverted text zones and normal text zones within the same document.

The document structure analysis and character recognition are usually done in several phases: scanning thresholding skew detection and correction despeckle or speckle removal line removal border removal detection of preprinted elements (like boxes) page orientation detection and correction layout analysis classification character recognition (normal and inverse)Each step must be completed well enough for the performance of the sequence and result to be successful.

ZoneHelper detects and automatically converts inverted text zones and change white-on-black text to normal black-on-white text.ZoneHelper expects as input a monochrome image.