Options
The filter accepts the following options:
- 'cx'
-
Relative x-coordinate of the focal point of the image, and thereby the center of the distortion. This value has a range [0,1] and is expressed as fractions of the image width. Default is 0.5.
- 'cy'
-
Relative y-coordinate of the focal point of the image, and thereby the center of the distortion. This value has a range [0,1] and is expressed as fractions of the image height. Default is 0.5.
- 'k1'
-
Coefficient of the quadratic correction term. This value has a range [-1,1]. 0 means no correction. Default is 0.
- 'k2'
-
Coefficient of the double quadratic correction term. This value has a range [-1,1]. 0 means no correction. Default is 0.
The formula that generates the correction is:
r_src = r_tgt * (1 + k1 * (r_tgt / r_0)^2 + k2 * (r_tgt / r_0)^4)
where r_0 is halve of the image diagonal and r_src and r_tgt are the distances from the focal point in the source and target images, respectively.