Method for image encoding

Apparatus for embedding data in an image, the apparatus comprising:

• a computer memory for storing the image as an ordered set of pixels, each pixel having a pixel parameter value;
• means for identifying plural points within the image;
• and
• image altering means for increasing the parameter value of each of a first group of said identified points, and also for increasing the parameter values of a first patch of points surrounding each such point;
• said image altering means further decreasing the parameter value of each of a second group of said identified points, and also for decreasing the parameter values of a second patch of points surrounding each such point.

A method of encoding N bits of first data, N being at least one, within a work of authorship represented by plural elements of second data, each element having a value, the method including, for each bit of the first data:

• mapping said bit to at least one element of the second data by a process that includes a random function;
• and
• changing the value of said at least one element of the second data;
• wherein changes to the work of authorship are essentially human imperceptible.

A method of encoding N-bits of auxiliary data within a source signal, N being at least one, the method including:

• evaluating data hiding characteristics of plural locations in the source signal;
• and
• encoding the auxiliary data in the source signal, avoiding the locations that have poor data hiding characteristics;
• wherein the auxiliary data is encoded where it is relatively less perceptible, said encoding resulting in changes to the source signal that are so slight as to be essentially imperceptible to humans.

A method of encoding N-bits of auxiliary data within an image represented by a set of data, N being at least one, the method including:

• evaluating data hiding characteristics of different portions of said set of data;
• and
• encoding the auxiliary data in the set of data, avoiding the portions that have poor data hiding characteristics;
• wherein the auxiliary data is encoded where it is relatively less perceptible, said encoding resulting in changes to the image that are so slight as to be essentially imperceptible to humans.

A method of encoding N-bits of auxiliary data within an image represented by a set of data, N being at least one, the method including:

• identifying portions of the set of data having a predetermined data hiding attribute;
• and
• changing the set of data in at least certain of said portions to effect encoding of the auxiliary data therein;
• wherein the auxiliary data is encoded where it is relatively less perceptible, said encoding resulting in changes to the image that are so slight as to be essentially imperceptible to humans.

A method of encoding N-bits of auxiliary data within a source signal, N being at least one, the method including:

• identifying portions of the source signal having a predetermined data hiding attribute;
• and
• changing the source signal in at least certain of said portions to effect encoding of the auxiliary data therein;
• wherein the auxiliary data is encoded where it is relatively less perceptible, said encoding resulting in changes to the source signal that are so slight as to be essentially imperceptible to humans.