Correction of Camera Lens Distortion

Digital camera usually introduces significant distortion caused by the camera and lens. These distortions cause errors in any analysis of the image. The functions described in this section correct these distortion using intrinsic camera parameters and distortion coefficients. These intrinsic camera parameters are focal lengths fx, fy, and principal point coordinates cx, cy. The distortion is characterized by two coefficients of radial distortions k₁, k₂ and two coefficients of tangential distortions p₁, p₂.

The undistorted coordinates x_u and y_u of point with coordinates (x_d, y_d) are computed in accordance with the following formulas:

Here r² = x_d² + y_d², x_d = (j-cx)/fx, y_d = (i-cy)/fy; i and j are row and columns numbers of the pixel. The pixel value is computed using bilinear interpolation of four nearest pixel of the source image. If undistorted coordinates are outside the image, then the destination pixel is not changed.

• UndistortGetSize
  Computes the size of the external buffer.
• UndistortRadial
  Corrects radial distortions of the single image.
• CreateMapCameraUndistort
  Creates look-up tables of coordinates of corrected image.

From：http://software.intel.com/sites/products/documentation/hpc/ipp/ippi/ippi_ch14/ch14_correction_of_camera_lens_distortion.html