Digital watermarking

A method for extracting, using a processor, digital watermark data embedded in image data representing a number of pixels, each of which has a respective saturation value, the method comprising the following steps:

• a) using said processor, dividing the image into blocks of pixels of a predefined size;
• b) for each block, using said processor to compare the saturation of pixels within the block with a plurality of saturation patterns, each representing a different binary value, and to select a matching saturation pattern that most closely matches the saturation of pixels within the block;
• and
• c) for each block, using said processor to assign the binary value represented by the matching saturation pattern to one or more bits of the digital watermark data corresponding to the block.

A system comprising a processor and a memory, the processor being adapted to execute a set of computer-readable instructions stored in the memory, thereby to embed digital watermark data into image data representing a number of pixels, each of which has respective saturation values, by a method comprising the following steps:

• a) using said processor, dividing the image into blocks of pixels of a predefined size;
• b) for each block, using said processor to select one of a plurality of saturation patterns representing the binary value of one or more bits of the digital watermark data corresponding to the block;
• and
• c) for each block, using said processor to embed the binary value of the one or more bits of corresponding digital watermark data into the block by adjusting the saturation of pixels within each block in accordance with the selected pattern.

A system comprising a processor and a memory, the processor being adapted to execute a set of computer-readable instructions stored in the memory, thereby to extract digital watermark data embedded in image data representing a number of pixels, each of which has a respective saturation value, by a method comprising the following steps:

• a) using said processor, dividing the image into blocks of pixels of a predefined size;
• b) for each block, using said processor to compare the saturation of pixels within the block with a plurality of saturation patterns, each representing a different binary value, and to select a matching saturation pattern that most closely matches the saturation of pixels within the block;
• and
• c) for each block, using said processor to assign the binary value represented by the matching saturation pattern to one or more bits of the digital watermark data corresponding to the block.

A computer program comprising a set of computer-readable instructions adapted, when executed on a computer device, to cause said computer device to embed digital watermark data into image data representing a number of pixels, each of which has respective saturation values, by a method comprising the following steps:

• a) using said processor, dividing the image into blocks of pixels of a predefined size;
• b) for each block, using said processor to select one of a plurality of saturation patterns representing the binary value of one or more bits of the digital watermark data corresponding to the block;
• and
• c) for each block, using said processor to embed the binary value of the one or more bits of corresponding digital watermark data into the block by adjusting the saturation of pixels within each block in accordance with the selected pattern.

A computer program comprising a set of computer-readable instructions adapted, when executed on a computer device, to cause said computer device to extract digital watermark data embedded in image data representing a number of pixels, each of which has a respective saturation value, by a method comprising the following steps:

• a) using said processor, dividing the image into blocks of pixels of a predefined size;
• b) for each block, using said processor to compare the saturation of pixels within the block with a plurality of saturation patterns, each representing a different binary value, and to select a matching saturation pattern that most closely matches the saturation of pixels within the block;
• and
• c) for each block, using said processor to assign the binary value represented by the matching saturation pattern to one or more bits of the digital watermark data corresponding to the block.