Image processing apparatus and method for preferably correcting distortion aberration

An image processing apparatus comprising:

• a distortion correcting part for correcting pixels of image data having a distortion due to distortion aberration characteristics of an optical system, and outputting corrected image data;
• a filtering part for applying a predetermined filtering process based on a filter coefficient to the image data to be input into the distortion correcting part;
• a measuring part for measuring distance data or relative coordinate data from a position corresponding to an optical center of the optical system to a target pixel for applying the filtering process on the image data, the distance data being given in a r2 form where r is a distance;
• and
• a filter coefficient setting part for setting the filter coefficient which is used in the filtering part and is assigned to a position of the target pixel in accordance with the distortion aberration characteristics, where the filter coefficient setting part sets the filter coefficient so as to obtain substantially uniform spatial frequency characteristics for the image data after the distortion correction by the distortion correcting part based on the distance data or the relative coordinate data measured by the measuring part,
• wherein the optical system includes a group of cylindrical lenses having independent distortion aberration characteristics with respect to directions which are perpendicular to each other on a plane, wherein the distortion aberration characteristics are rotationally asymmetrical, and the plane has a normal which coincides with the optical center.