Image authentication patterning

Abstract

Apparatus for producing a self-authenticating visual image of a selected view, using a digital image forming means, such as a digital camera, together with a position determining system that provides position information, including location and/or angular orientation and/or time of observation at the time a digital image is formed and/or distance from the camera to a selected object. The digital image of the selected view is presented as an array of pixels with associated pixel values. The position information is incorporated in the digital image by altering selected pixel bit values for a selected authentication pattern P of pixels in a chosen subset CS of the pixel array; and this selected pattern may be determined using the position information. The position information may be encrypted, using an encryption key based on position information, and may be stored separate from, or as part of, the digital image. The authentication pattern is represented by an authentication key or indicium, a single number or an ordered sequence of numbers, that is transmitted with the modified digital image and incorporated position information. The authentication pattern P is preferably chosen so that any circle or other connected pixel region of diameter at least equal to a selected number D contains at least one pixel from the subset CS. The pixel array may be overlaid by a set of polygons, such as triangles, rectangles, parallelograms or hexagons, with at least one pixel from the subset CS in each polygon.