Duo-frame normalization technique

• US 5,434,612 A
• Filed: 05/17/1994
• Issued: 07/18/1995
• Est. Priority Date: 09/25/1992
• Status: Expired due to Fees

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Nettleton, John E., Barr, Dallas N.
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Le, Vu
• Application Number:
  US08/243,726
• Time in Patent Office: 427 Days
• Field of Search: 348/31
• US Class Current: 348/31
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

A duo-frame normalization technique and system for use in range gate imag to determine a range coded image by use of two image frames. A transmitter emits a modulated energy pulse which is not gated when received by a single gated imaging camera to obtain an integrated first image frame and gated by the same camera when received as an integrated second image frame. The second integrated frame is divided by the first integrated frame to yield a range coded pixel intensity image. Three gated imagining cameras can also be used that share common imaging optics via filters and beam splitters so as to compensate for phenomenological issues that can vary the signals from one frame to another and lead to degraded range images.

Claims

1. A duo-frame normalization technique for use in range gate imaging to compensate for phenomenological effects, including the steps of:

generating an energy pulse;

transmitting over a range interval the energy pulse to a target;

simultaneously receiving,

a) ambient light present over an open gated range as an integrated ambient image;

b) a reflected energy pulse from said target over the open-gated range as an integrated first gate image;

c) the reflected energy pulse from said target over a shortened gate range as an integrated second gate image;

normalizing the integrated ambient image;

subtracting the integrated normalized ambient image from both the integrated first gate image and the integrated second gate image, to yield a first and second frame integration;

dividing the second frame integration by the first frame integration whereby a range-coded image is obtained in a time that is relatively short as compared to dynamic scene effects so as to substantially remove all dynamic scene effects from the range-coded image.