On Thursdays the USPTO publishes new patent applications. Both of today's Spotlight Applications address aspects of digital watermarking. Assigned to Philips, the first application discloses techniques for watermark detection. Assigned to The Hong Kong University Of Science And Technology (HK), the second application discloses techniques for loss-less watermarking.
20090019286, "Watermark Detection," assigned to Philips (NL).
Abstract
A detector (100) detects the presence of a watermark in an information signal. The information signal is correlated with an expected watermark (Wi) for each of a plurality of relative positions of the information signal with respect to the watermark to derive a set of correlation results (64). Part of the correlation results (64) are cross-correlated (82) with information (81) about an expected shape of a correlation peak in the results. This can improve the sensitivity of the detector (100). The cross-correlation result (84) is compared with a threshold at peak detection unit (85). The threshold used in this comparison (85) is set in an adaptive manner according to the expected shape. The information (81) about an expected shape of the correlation peak can be based on knowledge of processing operations that the information signal has undergone or expected to have undergone or from the shape of previous correlation results.
20090010483, "Block-Based Lossless Data Hiding In The Delta Domain," assigned to The Hong Kong University Of Science And Technology (HK).
Abstract
A system and methodology for encoding or decoding hidden data, such as a digital watermark, in raster media is provided in delta domain, a domain that creates a high-pass version of the raster media. Hidden data, such as a watermark, can be embedded in the general smooth region (low variance region) while a strong edge is preserved. A Mean-Square Error (MSE) reduction can be obtained by embedding the watermark in the delta domain. Using checkerboard-pattern watermark sequences and the delta domain, at least half of the total pixels in the image remain unchanged after watermark embedding. In order to recover the hidden data, some side information can be conveyed, in-band or out-of-band, to a decoder, such as various parameters used when performing the method. If protection from attacks, such as a JPEG encoding attack is desired, a location map can be provided to assist with hidden data recovery.
