Visible and invisible watermarking of printed images via 2nd generation stochastic seed frequency modulation

Patent metadata

Field	Value
Publication number	US-8970910-B2
Application number	US-201113313329-A
Country	US
Kind code	B2
Filing date	Dec 7, 2011
Priority date	Dec 7, 2011
Publication date	Mar 3, 2015
Grant date	Mar 3, 2015

Abstract

As set forth herein, computer-implemented methods and systems facilitate watermarking documents and/or images using 2 nd generation stochastic halftoning. The watermark is used to spatially vary the gray level at which a frequency modulation-to-amplitude modulation transition occurs. The encoding algorithm uses as inputs a contone image and a watermark. The visibility of the watermark is controlled by the magnitude of the difference between the AM-to-FM transition threshold values.

First claim

The invention claimed is:

1. A computer-implemented method for generating a watermarked halftone image using 2 nd generation stochastic halftoning to binarize pixels, comprising:
receiving a contone input image and watermark image data;
determining seed locations based on a gray level of the input image at given locations within the image and based on a presence or absence of a watermark at those locations, where watermark regions have a first FM-to-AM transition threshold and…

Assignees

• Bernal Edgar A
• Wang Shen-Ge
• Loce Robert P
• Fan Zhigang
• Xerox Corp

Inventors

• Bernal Edgar A
• Wang Shen-Ge
• Loce Robert P
• Fan Zhigang

Classifications

• G06T1/0021 Primary

  Physics · mapped topic

• H04N1/32256

  Electricity · mapped topic

• G06T1/0028 Primary

  Physics · mapped topic

• G06T2201/0051

  Physics · mapped topic