A steganographic image encoding method (100) is disclosed. The method
(100) defines a candidate set of incoherent pixel groups in a digital
image, each pixel group comprising at least two pixels. A subset of the
candidate set of pixel groups is selected using a predefined selection
criterion and an integer colour value is assigned to each of a plurality
of colours. The information is embedded in the image by modifying colour
values of pixels of the selected subset of pixel groups such that the
information is embedded in accordance with the order of the integer
colour values corresponding to the colour values after modification.