I try to make image some changes(crop, resize, undistort) and I want to know how distortion coefficients and camera intrinsinc parameters change after that.
- Origin Image shape = [848, 480]
- camera matrix = [[fx, 0, cx], [0, fy, cy], [0, 0, 1]]
- distortion coefficients = [k1, k2, p1, p2]
crop
- [848, 480] -> [582, 326]
- fx, fy : no changes
- cx, cy : cx -133, cy - 77
- distortion coefficients -> ??
resize
- [582, 326] -> [848, 480]
- fx, cx -> 1.457fx, 1.457cx
- fy, cy -> 1.472fy, 1.472cy
- [k1, k2, p1, p2] -> [k1, k2, p1, p2] same
undistort
- fx, fy, cx, cy -> same
- [k1, k2, p1, p2] -> [0, 0, 0, 0]
Does anyone knows the answer?
For me I tried using my camera and calibrate some results but I don't know the exact equation.
origin
- fx = 402.242923
- fy = 403.471056
- cx = 426.716067
- cy = 229.689399
- k1 = 0.068666
- k2 = -0.039624
- p1 = -0.000182
- p2 = -0.001510
crop
- fx = 408.235312 -> almost no change
- fy = 409.653612 -> almost no change
- cx = 297.611639 -> cx - 133
- cy = 153.667098 -> cy - 77
- k1 = 0.048520 -> I don't know
- k2 = -0.010035 -> I don't know
- p1 = 0.000943 -> I don't know
- p2 = -0.000870 -> I don't know
crop_resize
- fx = 598.110106 -> almost * 1.457
- fy = 608.949995 -> almost * 1.472
- cx = 430.389861 -> almost * 1.457
- cy = 226.585804 -> almost * 1.472
- k1 = 0.054762 -> I don't know
- k2 = -0.025597 -> I don't know
- p1 = 0.002752 -> I don't know
- p2 = -0.001316 -> I don't know
undistort
- fx = 404.312916 -> almost same
- fy = 405.544033 -> almost same
- cx = 427.986926 -> almost same
- cy = 229.213162 -> almost same
- k1 = -0.000838 -> almost 0
- k2 = 0.001244 -> almost 0
- p1 = -0.000108 -> almost 0
- p2 = 0.000769 -> almost 0
All part you write as "I don't know" will be "same(not changed)".
Because Cropping and Resizing is representable with only (cx,cy,fx,fy).