Systems and methods for dewarping images

• US 9,547,883 B1
• Filed: 08/19/2016
• Issued: 01/17/2017
• Est. Priority Date: 08/19/2016
• Status: Active Grant

• Current Assignee: Intelligent Security Systems (ISS)
• Original Assignee: Intelligent Security Systems (ISS)
• Inventors: Stepanenko, Oleg Vladimirovich
• Primary Examiner(s): NGUYEN, ANH TUAN V
• Application Number:
  US15/241,770
• Time in Patent Office: 151 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06T 15/20 Perspective computation
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 3/12 Panospheric to cylindrical image transformations
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture

Abstract

A computer-implemented method comprises: extracting a setting from a description file of a virtual pan-tilt-zoom (PTZ) camera used to capture an original image through a wide-angle lens; determining a first set of coordinates of a pixel of the original image for each cell of a sparse conversion map represented as a first look-up table, wherein the sparse conversion map corresponds to a sparse grid of pixels of an output image; determining, via interpolating the first set of coordinates, a second set of coordinates of a pixel of the original image for each cell of a full conversion map, wherein the second set of coordinates is represented as a second look-up table, wherein the full conversion map corresponds to a full grid of pixels of the output image; instructing a display to present the output image, wherein the original image is less rectilinear than the output image.

Claims

1. A method of image conversion, the method comprising:

extracting, by a processor, a setting from a description file of a virtual pan-tilt-zoom (PTZ) camera used to capture an original image through a wide-angle lens, wherein the description file contains a minimum viewing angle value, a maximum viewing angle value, and a border viewing angle value between the minimum viewing angle value and the maximum viewing angle value;

determining, by the processor, based on the extracting, a distortion removal coefficient value for an output image based on a search of a balance between a viewing angle value of the virtual PTZ camera and a degree of a removal of a distortion introduced in the original image by the wide-angle lens, wherein determining the distortion removal coefficient value comprises;

setting the distortion removal coefficient value to zero when the viewing angle value is equal to the maximum viewing angle value;

setting the distortion removal coefficient value to between zero and one when the viewing angle value is less than the maximum viewing angle value and greater than the border viewing angle value, respectively; and

setting the distortion removal coefficient value to one when the viewing angle value is less than or equal to the border viewing angle value and greater than or equal to the minimum viewing angle;

determining, by the processor, based on the distortion removal coefficient value, a first set of coordinates for a pixel of the original image for each cell of a sparse conversion map, wherein the first set of coordinates is represented as a first look-up table, wherein the sparse conversion map corresponds to a sparse grid of pixels of the output image;

determining, by the processor, via interpolating the first set of coordinates, a second set of coordinates of a pixel of the original image for each cell of a full conversion map, wherein the second set of coordinates is represented as a second look-up table, wherein the full conversion map corresponds to a full grid of pixels of the output image;

instructing, by the processor, based on the interpolating, a display to present the output image such that the output image can be modified via an input controlling the viewing angle value, wherein the output image fully includes the distortion when the distortion removal coefficient value is zero, partially includes the distortion when the distortion removal coefficient value is between zero and one, and includes no distortion when the distortion removal coefficient value is one.

2. The method of claim 1, wherein the controlling is in real-time.

3. The method of claim 1, wherein the first look-up table and the second look-up table are comprised in a single data structure.

4. The method of claim 1, wherein the first look-up table and the second look-up table are comprised in a plurality of distinct data structures.

5. The method of claim 1, wherein the display comprises a video wall.

6. The method of claim 1, wherein the processor is local to the virtual PTZ camera.

7. The method of claim 1, wherein the processor is remote from the virtual PTZ camera.

8. The method of claim 1, wherein the input is via a graphical user interface presented on the display, wherein the graphical user interface depicts the output image.

9. A system comprising:

a server storing a set of instructions to perform a method of image conversion, the method comprising;

extracting, by a processor, a setting from a description file of a virtual pan-tilt-zoom (PTZ) camera used to capture an original image through a wide-angle lens, wherein the description file contains a minimum viewing angle value, a maximum viewing angle value, and a border viewing angle value between the minimum viewing angle value and the maximum viewing angle value;

determining, by the processor, based on the extracting, a distortion removal coefficient value for an output image based on a search of a balance between a viewing angle value of the virtual PTZ camera and a degree of a removal of a distortion introduced in the original image by the wide-angle lens, wherein the output image has same distortion as the original image when the viewing angle value of the virtual PTZ camera is set to the maximum viewing angle value and the distortion removal coefficient value is set to zero, wherein determining the distortion removal coefficient value comprises;

setting the distortion removal coefficient value to zero when the viewing angle value is equal to the maximum viewing angle value;

setting the distortion removal coefficient value to between zero and one when the viewing angle value is less than the maximum viewing angle value and greater than the border viewing angle value, respectively; and

setting the distortion removal coefficient value to one when the viewing angle value is less than or equal to the border viewing angle value and greater than or equal to the minimum viewing angle;

determining, by the processor, based on the distortion removal coefficient value, a first set of coordinates for a pixel of the original image for each cell of a sparse conversion map, wherein the first set of coordinates is represented as a first look-up table, wherein the sparse conversion map corresponds to a sparse grid of pixels of the output image;

determining, by the processor, via interpolating the first set of coordinates, a second set of coordinates of a pixel of the original image for each cell of a full conversion map, wherein the second set of coordinates is represented as a second look-up table, wherein the full conversion map corresponds to a full grid of pixels of the output image;

instructing, by the processor, based on the interpolating, a display to present the output image such that the output image can be modified via an input controlling the viewing angle value, wherein the output image fully includes the distortion when the distortion removal coefficient value is zero, partially includes the distortion when the distortion removal coefficient value is between zero and one, and includes no distortion when the distortion removal coefficient value is one.

10. The system of claim 9, wherein the controlling is in real-time.

11. The system of claim 9, wherein the first look-up table and the second look-up table are comprised in a single data structure.

12. The system of claim 9, wherein the first look-up table and the second look-up table are comprised in a plurality of distinct data structures.

13. The system of claim 9, wherein the display comprises a video wall.

14. The system of claim 9, wherein the processor is local to the virtual PTZ camera.

15. The system of claim 9, wherein the processor is remote from the virtual PTZ camera.

16. The system of claim 9, wherein the input is via a graphical user interface presented on the display, wherein the graphical user interface depicts the output image.