On the Design of Pattern Sequences for Spread Spectrum Image Watermarking

"This article investigates pattern sequences for Direct Sequence Code Division Multiple Access (DS-CDMA) spread spectrum communication of image watermarks. The problem is stated and three choices of sequence generation are proposed, namely: traditional pseudorandom generation, deterministic sequences from Walsh and Hadamard basis, and generation by Gram-Schmidt orthogonalization of pseudorandom sequences. The desirable properties for a sequence are defined and the choices are compared based on the detection reliability of the watermark. We present analysis, comparisons and conclusions about the proper choice of sequences for watermarking applications."