Watermarking of digital images using watermark-indicators

A system for watermarking a digital image, comprising:

• at least one processor;
• an image transform module coupled to the at least one processor and configured to transform, using the at least one processor, the digital image to a plurality of coefficient blocks of coefficients in a frequency domain;
• a watermark embedding module coupled to the at least one processor and configured to embed, using the at least one processor, a watermark in each of a plurality of watermark blocks to generate a watermarked digital image, each watermark block in the plurality of watermark blocks having a predetermined number of coefficient blocks from said set of coefficient blocks and a predetermined number of group-of-blocks, wherein each group-of-blocks has a predetermined number of coefficient blocks from the set of coefficient blocks and wherein to embed the watermark, the watermark embedding modules is further configured to divide the watermark into a plurality of watermark-units, select a watermark-unit from the plurality of watermark-units and encode the selected watermark-unit in a group-of-blocks in each watermark block, wherein to encode the selected watermark-unit, the watermark embedding module is further configured to select a watermark coefficient set in a group-of-blocks from said group-of-blocks in each watermark block and modify coefficients in the watermark coefficient set, the modifying including the watermark embedding module being further configured to select a watermark contributor coefficient set for the watermark coefficient set, wherein the watermark contributor coefficient set and the watermark coefficient set are located in one group-of-blocks and calculating each coefficient in the watermark coefficient set based on the watermark contributor coefficient set;
• and
• a watermark-indicator embedding module coupled to the at least one processor and configured to embed, using the at least one processor, a watermark-indicator in each of a plurality of said coefficient blocks.

An article of manufacture comprising a non-transitory computer readable medium encoding instructions thereon that, in response to execution by a processor, cause the processor to embed a watermark in a digital image using operations comprising:

• transforming the digital image to a set of coefficient blocks having coefficients in a frequency domain;
• embedding a watermark-indicator in each of a plurality of coefficient blocks of said set of coefficient blocks;
• embedding a watermark in each of a plurality of watermark blocks to generate a watermarked digital image, each watermark block in the plurality of watermark blocks having a predetermined number of coefficient blocks from said set of coefficient blocks and a predetermined number of group-of-blocks, wherein each group-of-blocks has a predetermined number of coefficient blocks from the set of coefficient blocks and wherein embedding the watermark includes dividing the watermark into a plurality of watermark-units, selecting a watermark-unit from the plurality of watermark-units and encoding the selected watermark-unit in a group-of-blocks in each watermark block, the encoding including selecting a watermark coefficient set in a group-of-blocks from said group-of-blocks in each watermark block and modifying coefficients in the watermark coefficient set, the modifying including selecting a watermark contributor coefficient set for the watermark coefficient set, wherein the watermark contributor coefficient set and the watermark coefficient set are located in one group-of-blocks and calculating each coefficient in the watermark coefficient set based on the watermark contributor coefficient set;
• and
• outputting the watermarked digital image.