×

Method for determining document background for adjusting the dynamic range of an image of the document

  • US 6,198,845 B1
  • Filed: 07/01/1997
  • Issued: 03/06/2001
  • Est. Priority Date: 07/01/1997
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for determining a background grey-level of a document, comprising:

  • generating a histogram of grey-level values from a sampling window of the document;

    smoothing the histogram;

    determining a curve approximating a shape of the smoothed histogram;

    determining a mean and standard deviation of the curve;

    determining a gain of the document based on the mean and standard deviation and a maximum grey-level value of the histogram; and

    determining the background grey-level of the document based on the gain.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×