Distortion in Photography arises due to geometric aberrations of optical systems, which leads to a local change in the scale of imaging. Unlike noise in Digital Photography, modification Distortion in Photography is based on a change in magnification with increasing distance of the image from the optical axis. Distortion in Photography is therefore rotationally symmetric around a point.
What is Distortion in Photography
The magnification of the edges of the image field, creates a square cushion shaped magnifies the edges of the image field, this is normal. In the opposite case is the situation that arises is called barrel distortion. There may also be higher order distortion and the superposition of different orders distortion in Photography can lead to a wave like figure of straight lines. Fish-eye lens has a strong barrel distortion by nature.
For optical devices including camera for everyday use, the distortion is not perceptible as disadvantage and is therefore not taken into account. Thus glasses for nearsighted with minus power has a strong barrel distortion. For devices with multiple lenses, such as telescopes, distortion can be minimized by optical compensation by the use of different lenses of different thickness and curvature.
Types of glass (crown glass, flint glass) has different refractive indexes and combination in complex lenses helps to flatten the distortion in Photography. This distortion free optics are called orthoscopic lens system in medically significant lens system.
Photographic images are used for preciseness, so a corrected lens system for correcting distortion is required. In addition, the remaining distortion is determined by measurement and the evaluation of the image corrected by calculation by the software.
Correction of distortion in Photography
By reversing these models, the errors can be corrected, the actual distortion of an image is thus made to a corrected image. In barrel distortion the equalized image is larger and in pincushion distortion it is smaller when the magnification at the center remains unchanged. Some software uses the mathemetical formula of Optics to correct the distortion in Photography.