An optical blurring filter which is resistant to digital image restoration

摘要

An optical filter for intentionally blurring camera images has a generally transparent material and a plurality of optical distortions formed in the transparent material. Placement of the transparent material longitudinally in the optical path of a camera in front of the aperture stop allows contouring the blur across the image plane. That contour is preferably random, so as to defeat digital methods for image restorations. Additionally, a linear gradient is utilized to even-out the ground resolution on oblique cameras or localized to even-out resolution on cameras that have areas of unwanted high resolution.