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X u = x d + ( x d − x c ) ( K 1 r 2 + K 2 r 4 + ⋯ ) + ( P 1 ( r 2 + 2 ( x d − x c ) 2 ) + 2 P 2 ( x d − x c ) ( y d − y c ) ) ( 1 + P 3 r 2 + P 4 r 4 ⋯ ) y u = y d + ( y d − y c ) ( K 1 r 2 + K 2 r 4 + ⋯ ) + ( 2 P 1 ( x d − x c ) ( y d − y c ) + P 2 ( r 2 + 2 ( y d − y c ) 2 ) ) ( 1 + P 3 r 2 + P 4 r 4 ⋯ ), A graph showing radius transformations (from object to image) will be less steep in the upper (rightmost) end. Conversely, barrel distortion is actually a diminished radius mapping for large radii in comparison with small radii. A graph showing radius transformations (from object to image) will be steeper in the upper (rightmost) end. It will then be observed that these common distortions actually imply a nonlinear radius mapping from the object to the image: What is seemingly pincushion distortion, is actually simply an exaggerated radius mapping for large radii in comparison with small radii. In order to understand these distortions, it should be remembered that these are radial defects the optical systems in question have rotational symmetry (omitting non-radial defects), so the didactically correct test image would be a set of concentric circles having even separation-like a shooter's target.
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Radial distortions can be understood by their effect on concentric circles, as in an archery target. Other distortions are in principle possible – pincushion in center and barrel at the edge, or higher order distortions (degree 6, degree 8) – but do not generally occur in practical lenses, and higher order distortions are small relative to the main barrel and pincushion effects. In mustache distortion the quartic (degree 4) term is significant: in the center, the degree 2 barrel distortion is dominant, while at the edge the degree 4 distortion in the pincushion direction dominates. Mathematically, barrel and pincushion distortion are quadratic, meaning they increase as the square of distance from the center. It starts out as barrel distortion close to the image center and gradually turns into pincushion distortion towards the image periphery, making horizontal lines in the top half of the frame look like a handlebar mustache. The visible effect is that lines that do not go through the centre of the image are bowed inwards, towards the centre of the image, like a pincushion.Ĭonvex (plus) spherical lenses tend to have pincushion distortion.Ī mixture of both types, sometimes referred to as mustache distortion ( moustache distortion) or complex distortion, is less common but not rare. In pincushion distortion, image magnification increases with the distance from the optical axis. Ĭoncave (minus) spherical lenses tend to have barrel distortion. In a zoom lens, barrel distortion appears in the middle of the lens's focal length range and is worst at the wide-angle end of the range. Fisheye lenses, which take hemispherical views, utilize this type of distortion as a way to map an infinitely wide object plane into a finite image area.
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The apparent effect is that of an image which has been mapped around a sphere (or barrel). Hopefully a newer version may work, so I will keep my fingers crossed and keep checking updates.In barrel distortion, image magnification decreases with distance from the optical axis. $25 isn't much, but as an unemployed person I cannot even spend $25 on something that likely will not work.
PTLENS REVIEW SOFTWARE
So it seems that either some software or hardware on my system is in conflict with his software. Unfortunately the author of the program recommends that I don't buy it because it would likely not work on my computer. Hi Ian, if I had some guarantee that it would work I would gladly buy it. If you need lens correction PTLens is a brialliant piece of software, just buy it would be the simple solution
PTLENS REVIEW LICENSE
However, PTLens is a $25 program for a lifetime license and is constantly being improved - an absolute bargain. If the software was expensive and had a limited life it might be worth worrying about.
PTLENS REVIEW CODE
Trial software can be a little flaky as the author has to put code on the computer to prevent low lifes simply reinstalling the trial software rather than pay the asking price.