Utilizing dependency between watermark visibility and location of image sample in color space for embedded signal color direction

Abstract

The present disclosure relates generally to signal encoding for printed objects. One implementation selects an embed direction based on a minimal visibility axis of a 1 JND ellipse at a certain color center. One claim recites an apparatus comprising: memory for storing chromatic contrast sensitivity data representing multiple color encoding angles; one or more multi-core processors configured for: using the stored chromatic contrast sensitivity data, generating an ellipse around a first color center; and from the ellipse, determining a signal encode direction, the signal encode direction comprising an angle α representing a negative angle between the ‘a*’ axis in an CIELAB space and a direction of minimum sensitivity of an encoded signal, in which the angle α comprises −9 degrees≥α≥−25 degrees. Other technology described.

Dependencies are inferred from the claim text.