Method of eliminating background noise

• US 8,493,479 B2
• Filed: 04/27/2011
• Issued: 07/23/2013
• Est. Priority Date: 04/27/2011
• Status: Active Grant

• Current Assignee: Authentix, Inc.
• Original Assignee: Eastman Kodak Company
• Inventors: Widzinski, Thomas J., Pawlik, Thomas D., Allmann, Erwin L., Spinelli, Gary M., Olm, Myra T.
• Primary Examiner(s): Velez, Roberto
• Assistant Examiner(s): Tissire, Abdelaaziz
• Application Number:
  US13/094,973
• Publication Number:
  US 20120274819A1
• Time in Patent Office: 818 Days
• Field of Search: 348/250
• US Class Current: 348/250
• CPC Class Codes: G06V 20/80 Recognising image objects characterised by unique random patterns
• CPC Class Codes: G07D 7/2008 using pre-processing, e.g. de-blurring, averaging, normalisation or rotation

Abstract

A method of eliminating background noise from a system for authenticating security markers includes capturing an image of a background of the security marker; illuminating the security marker; capturing a plurality of images of the optical response of the security marker; averaging the plurality of optical response images; smoothing the background image; and subtracting the smoothed background image from the average of the plurality of optical response images.

Claims

1. A method of eliminating background noise from a system for authenticating security markers comprising:

capturing an image of a background with a security marker;

illuminating the security marker;

capturing a plurality of images of an optical response of the security marker;

averaging the plurality of optical response images;

smoothing the background image; and

subtracting the smoothed background image from the average of the plurality of optical response images.

2. The method of claim 1 comprising:

calculating a score based on the number of pixels above a predetermined threshold; and

authenticating the security marker if the score meets predetermined requirements.

3. The method of claim 1 wherein the images are captured by a CCD or CMOS sensor.

4. The method of claim 1 wherein smoothing the background image comprises applying a median filter on a pixel by pixel basis to the background image.

5. The method of claim 1 wherein averaging the plurality of optical response images comprises:

averaging the corresponding pixels of the plurality of images.

7. The method of claim 1 wherein averaging the plurality of optical response images comprises:

calculating a resulting image wherein each pixel value is an average of the corresponding pixel values of the plurality of images.

6. A method of eliminating background noise from a system for authenticating security markers comprising:

capturing a plurality of images of a background with a security marker;

averaging the background images;

illuminating the security marker;

capturing a plurality images of an optical response;

averaging the plurality of optical response images;

smoothing the averaged background image; and

subtracting the smoothed background image from the average of the plurality of optical response images.