Method for binarizing scanned document images containing gray or light colored text printed with halftone pattern

Patent metadata

Field	Value
Publication number	US-8947736-B2
Application number	US-94680110-A
Country	US
Kind code	B2
Filing date	Nov 15, 2010
Priority date	Nov 15, 2010
Publication date	Feb 3, 2015
Grant date	Feb 3, 2015

Abstract

A method for binarizing a scanned document images containing gray or light colored text printed with halftone patterns. The document image is initially binarized and connected image components are extracted from the initial binary image as text characters. Each text character is classified as either a halftone text character or a non-halftone text character based on an analysis of its topology features. The topology features may be the Euler number of the text character; a text character with a Euler number below −2 is classified as halftone text. The gray-scale document image is then divided into halftone text regions containing only halftone text characters and non-halftone text regions. Each region is binarized using its own pixel value statistics. This eliminates the influence of black text on the threshold values for binarizing halftone text. The binary maps of the regions are combined to generate the final binary map.

First claim

What is claimed is:

1. A method implemented in a data processing apparatus for binarizing a gray-scale document image which has been generated by scanning a paper-based document, the method comprising:
(a) identifying text characters in the gray-scale document image, including:
performing an initial binarization of the gray-scale image to generate an initial binary image; and
extracting connected image components in the initial binary image as text characters;

(b) classifyi…

Assignees

• Yu Songyang
• Ming Wei
• Konica Minolta Lab Usa Inc

Inventors

• Yu Songyang
• Ming Wei

Classifications

• H04N1/405

  Electricity · mapped topic

• H04N1/40062 Primary

  Electricity · mapped topic