Apparatus for centering and stabilizing the size of a target image

• US 4,476,494 A
• Filed: 03/24/1982
• Issued: 10/09/1984
• Est. Priority Date: 03/30/1981
• Status: Expired due to Term

• Current Assignee: Intertechnique SA (Safran SA)
• Original Assignee: Intertechnique SA (Safran SA)
• Inventors: Tugaye, Jean
• Primary Examiner(s): Martin, John C.
• Assistant Examiner(s): Sutherland, Jeffrey D.
• Application Number:
  US06/361,553
• Time in Patent Office: 930 Days
• Field of Search: 358/222, 358/125, 358/126, 358/113, 358/109, 364/516, 364/517, 364/565, 343/6 TV, 244/3.16, 244/3.17
• US Class Current: 348/208.6
• CPC Class Codes: F41G 7/2226 comparing the observed data with stored target data, e.g. target configuration data
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/7865 using correlation of the live video image with a stored image

Abstract

A stabilized image of a scene is provided by scanning the scene with a camera to provide pixels representative of the scene, providing individual representations of the pixels during each scan of the camera as digital words identifying an elevation address, an azimuth address, and the brightness of the pixel, generating a reference frame having a matrix of predetermined points each having an azimuth address and an elevation address, maintaining the frame in an invariable position with respect to the scene irrespective of angular movements of the camera, and for assigning the pixels to those of the points with which there is the best address match.

Claims

1. A method for real time stabilization of the image of a scene in the field of view of an optoelectrical camera, comprising the steps of:

generating a reference frame having an invariable location with respect to said scene, defined by a set of addresses representative of predetermined points of said frame, each said point having predetermined coordinates in said frame,

generating a series of pixels each representative of a particular point in the field of view of said camera,

determining the coordinates of each said pixel in said frame,

comparing the coordinates of each said pixel in said frame,

and assigning said pixels to those of said predetermined points of said frame with which there is the best match.

2. A method according to claim 1, wherein said pixels are assigned by transcoding addresses thereof to the addresses of particular ones of said points in said reference frame.

3. A method according to claim 1, wherein determination of the coordinates of said pixels includes:

determining coordinates of said pixels in said field of view;

and computing the true coordinates by correction in response to signal representing angular movements of said camera with respect to the scene.

4. A method according to claim 2, wherein said predetermined points have a spacing in at least one direction of said reference frame smaller than the spacing of said pixels in the same direction and transcoding is carried out by assigning each available pixel to the address in said direction of that predetermined point of the reference frame which is closest.

5. A method according to claim 2, wherein said predetermined points have a spacing in at least one direction of said reference frame which is greater than the spacing of said pixels in said direction and transcoding is carried out by assigning the address of each said point in said direction to that pixel which is closest in said direction.

6. Method according to claim 1, including scaling up and down said frame whereby a zoom effect is obtained.

7. Method according to claim 6, wherein the camera is movable toward and away from the scene and the reference frame is scaled up and down in relation with the distance between the scene for obtaining an image representation of constant width.

8. Apparatus for providing a stabilized image of a scene comprising:

a scanning optoelectrical camera for providing pixels representative of a scene,

means for providing individual representations of said pixels during each scan of the camera as digital words identifying an elevation address, an azimuth address and the brightness of said pixel,

means for generating a reference frame having a matrix of predetermined points each having an azimuth address and an elevation address.

means for maintaining said frame in an invariable position with respect to said scene irrespective of angular movements of said camera,

and comparison and transcoding means for assigning said pixels to those of said points with which there is the best address match.

9. Apparatus for providing a size stabilized image of a scene, comprising:

a scanning optoelectrical camera for providing pixels representative of a scene,

means for providing individual representations of said pixels during each scan of the camera as digital words identifying an elevation address, an azimuth address and the brightness of said pixel,

means for generating a reference frame having a matrix of predetermined points each having an azimuth address and an elevation address,

means for measuring the changes in distance between said camera and scene, and providing signals representative of said changes,

means responsive to said signals for scaling up and down said reference frame in response to variations in said distance,

and comparison and transcoding means for assigning said pixels to these of said points with which there is the best address match.