Modern camera lenses are relatively free of geometric distortion, especially so at focal lengths much longer than the film or sensor diagonal. However, there is always a small remaining amount even in the most expensive lenses. Radial distortion is most visible when taking pictures with wide angle lenses of vertical structures having straight lines which then appear curved. This kind of distortion appears most visibly when the shortest focal length is selected either with a fixed or a zoom lens. It may be adequately corrected by applying a simple polynomial transformation due to the 19th century mathematician and astronomer Philipp Ludwig von Seidel (1821-1896) published by him in 1856 which requires three constants affecting the image content as a function of the distance from the center and symmetrical about it, hence the name radial distortion. Radcor helps fighting back this distortions. Different control panels allow an easy calibration of your digital photos. Eliminate the distortion with ease and correct the colors settings as well.