DIGITAL WATERMARKING USING LOCAL CONTRAST-BASED TEXTURE MASKING

Digital image watermarking algorithms embed identifying marks that can be used for authentication. To make the distortions induced by the embedding process impercepti-ble, the watermarking algorithm must determine their vi-sual threshold. This paper presents: ( I) the results of a psychophysical detection experiment for wavelet-distortion targets presented 'against textured backgrounds of varying contrasts; and (2) an associated wavelet-based image wa-termarking algorithm that embeds the watermark at the threshold of visibility by weighting it using a local mask-ing measure prior to embedding. The embedded watermark is shown to be robust to JPEG compression at quality factors as low as 20. 1