Method and apparatus for obtaining rectilinear images using rotationally symmetric wide-angle lens

• US 9,762,795 B2
• Filed: 09/04/2013
• Issued: 09/12/2017
• Est. Priority Date: 09/04/2013
• Status: Expired due to Fees

• Current Assignee: Gyeongil Kweon
• Original Assignee: Gyeongil Kweon
• Inventors: Kweon, Gyeongil
• Primary Examiner(s): Beck, Leron
• Assistant Examiner(s): Boylan, James
• Application Number:
  US14/018,155
• Publication Number:
  US 20150062292A1
• Time in Patent Office: 1,469 Days
• Field of Search: 348 37
• CPC Class Codes: G06T 3/047 Fisheye or wide-angle transformations
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation

Abstract

The present invention provides mathematically accurate image processing algorithms for extracting natural looking panoramic images and distortion-free rectilinear images from images acquired using a camera equipped with a wide-angle lens which is rotationally symmetric about an optical axis and devices implementing such algorithms. Imaging systems using this method can be used not only in security•surveillance applications for indoor and outdoor environments, but also in diverse areas such as video phone for apartment entrance door, rear view camera for vehicles, visual sensor for unmanned aerial vehicles and robots, camera phone, PC camera, and broadcasting camera. Also, it can be used to obtain panoramic or rectilinear photographs using a digital camera.

Claims

1. An imaging system comprising:

an image acquisition means configured for acquiring an uncorrected image plane using a wide-angle lens rotationally symmetric about an optical axis,

an image processing means configured for extracting a rectilinear image plane from the uncorrected image plane; and

an image display means configured for displaying the rectilinear image plane on a rectangular screen,

wherein,

if a coordinate of an image point on the rectangular screen corresponding to an object point having a coordinate (X, Y, Z) in a world coordinate system, which has a nodal point of the wide-angle lens as an origin and a vertical line passing through the origin as an Y-axis, is given as (x″

, y″

),

arbitrary straight lines in the world coordinate system appear as straight, lines on the screen,

wherein,

the uncorrected image plane is a two dimensional array with K_max rows and L_max columns,

a pixel coordinate of the optical axis on the uncorrected image plane is (K_o, L_o),

a real projection scheme of the lens is an image height r obtained as a function of a zenith angle θ

of a corresponding incident ray and given as r=r(θ

),

a magnification ratio g of the camera is given as

2. A method of obtaining a rectilinear image, the method comprising:

acquiring an uncorrected image plane using a camera equipped with a wide-angle lens rotationally symmetric about an optical axis; and

extracting a processed image plane from the uncorrected image plane,

wherein,

the uncorrected image plane is a two dimensional array with K_max rows and L_max columns,

a pixel coordinate of the optical axis on the uncorrected image plane is (K_o, L_o)

a real projection scheme of the lens is an image height r obtained as a function of a zenith angle θ

of a corresponding incident ray and given as r=r(θ

),

a magnification ratio g of the camera is given as