How to correct barrel distortion in photos
Most consumer-grade cameras introduce a certain amount of "barrel distortion" in the pictures they take. The distortion is most easily visible at 1x zoom, in the form of a bulge in the middle of the image, and less visible to non-existent at maximum zoom.
Barrel distortion example - building with straight lines
You can easily spot the distortion if the photographed scene features straight horizontal lines.
Barrel distortion example - human subject
The real problem with barrel distortion is that most amateur photographers have no idea about it, let alone go through the trouble of correcting it. Worse, barrel distortion is not readily recognizable in photos of people or other subjects that don't feature straight horizontal lines. This makes human faces look bulged in photos and hence, un-photogenic.
Can you tell if the subject's face is distorted or not? Mouse over or out.
Barrel distortion correction
The good news is that you can correct this distortion through software. The most powerful software I found for distortion correction is ePaperPress PTLens. It ships with a database of camera distortion parameters and can automatically compensate for barrel, perspective, chromatic and other distortions.
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