Automatic detection of lens deviations

Patent metadata

Field	Value
Publication number	US-9348111-B2
Application number	US-201113215235-A
Country	US
Kind code	B2
Filing date	Aug 23, 2011
Priority date	Aug 24, 2010
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

An optical apparatus includes an image sensor, which outputs a signal responsively to an optical image formed on the image sensor. Objective optics focus optical radiation from an object so as to form the optical image on the image sensor, while superimposing a characteristic structure on the optical image. A processor processes the signal so as to generate an electronic image of the object while detecting, responsively to the characteristic structure, a deviation in an alignment of the objective optics relative to the image sensor.

First claim

The invention claimed is:

1. Optical apparatus, comprising:
an image sensor, which is configured to output a signal responsively to an optical image formed on the image sensor;
objective optics, which are configured to focus optical radiation from an object so as to form the optical image on the image sensor, while intentionally superimposing a known and invertible characteristic distortion on the optical image; and
a processor, which is coupled to process the signal so as to generate electronic images of the object and to apply an inverse digital warping to the electronic images in order to remove the characteristic distortion, to calibrate an initial distortion of the optical image by matching pairs of points in a first electronic image, each pair comprising an image point in the optical image and a corresponding point in an epipolar plane of the apparatus, to detect a change of the distortion in the optical image relative to the initial distortion using the matched pairs of points in a second electronic image, generated subsequently to the first electronic image, and to identify, responsively to the detected change, a deviation of a spatial or optical relation between the objective optics and the image sensor with respect to an initial alignment of the objective optics relative to the image sensor.

2. The apparatus according to claim 1 , wherein the deviation comprises a change in centering of the objective optics with respect to the image sensor relative to a default center of the alignment.

3. The apparatus according to claim 1 , wherein the deviation comprises a change in an effective focal length of the objective optics.

4. The apparatus according to claim 1 , wherein the processor is configured to estimate the distortion by finding a transformation of the pairs of the points that satisfies an epipolar constraint.

5. The apparatus according to claim 4 , wherein the processor is configured to detect the change the distortion by fitting a fundamental matrix to the pairs of the points in the first and second electronic images, and computing an error value of the fundamental matrix in the second electronic image.

6. The apparatus according to claim 1 , wherein the processor is configured to create a three-dimensional map of the object based on the pairs of the points in the optical image.

7. The apparatus according to claim 1 , and comprising a projection module, which is configured to project a pattern of the optical radiation onto the object, wherein the pairs of points comprise points in the projected pattern.

8. The apparatus according to claim 7 , wherein the processor is configured to process the pattern appearing in the electronic image while correcting for the deviation of the spatial or optical relation in order to generate a three-dimensional (3D) map of the object.

9. A method for imaging, comprising:
focusing optical radiation from an object via objective optics onto an image sensor so as to form an optical image on the image sensor, while intentionally superimposing on the optical image a known and invertible distortion that is characteristic of the objective optics;
processing a signal that is output by the image sensor so as to generate electronic images of the object and applying an inverse digital warping to the electronic images in order to remove the characteristic distortion;
calibrating an initial distortion of the optical image by matching pairs of points in a first electronic image, each pair comprising an image point in the optical image and a corresponding point in an epipolar plane;
detecting a change of the distortion in the optical image relative to the initial distortion using the matched pairs of points in a second electronic image, generated subsequently to the first electronic image; and
identifying, responsively to the detected change, a deviation of a spatial or optical relation between the objective optics and the image sensor with respect to an initial alignment of the objective optics relative to the image sensor.

10. The method according to claim 9 , wherein the deviation comprises a change in centering of the objective optics with respect to the image sensor relative to a default center of the alignment.

11. The method according to claim 9 , wherein the deviation comprises a change in an effective focal length of the objective optics.

12. The method according to claim 9 , wherein detecting the change in the distortion comprises finding a transformation of the pairs of the points that satisfies an epipolar constraint.

13. The method according to claim 12 , wherein finding the transformation comprises fitting a fundamental matrix to the pairs of the points in the first and second electronic images, and wherein detecting the change comprises computing an error value of the fundamental matrix in the second electronic image.

14. The method according to claim 9 , wherein processing the signal comprises creating a three-dimensional map of the object based on the pairs of the points in the optical image.

15. The method according to claim 9 , and comprising projecting a pattern of the optical radiation onto the object, wherein the pairs of points comprise points in the projected pattern.

16. The method according to claim 15 , and comprising processing the pattern appearing in the electronic image while correcting for the deviation in the alignment in order to generate a three-dimensional (3D) map of the object.

Assignees

• Cohen Yohan Yehouda
• Shpunt Alexander
• Pesach Benny
• Deitch Ronen
• Apple Inc

Inventors

• Cohen Yohan Yehouda
• Shpunt Alexander
• Pesach Benny
• Deitch Ronen

Classifications

• H04N25/61

  the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4" · CPC title

• G01M11/0221

  by determining the optical axis or position of lenses · CPC title

• H04N17/002

  for television cameras · CPC title

• G02B13/16

  for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV} · CPC title

• G01M11/0264

  by using targets or reference patterns · CPC title