This patent document relates generally to steganography and digital watermarking. One claim recites an apparatus comprising: memory for storing data representing an image or video, in which the data comprises first data corresponding to first color data, second data corresponding to second color data and third data corresponding to third color data, the image or video to host auxiliary information; a processor programmed for: weighting the first data, the second data and the third data according to at least the following two factors: i) a color direction associated with an expected embedding direction; and ii) expected image capture or signal processing; and determining from weighted first data, weighted second data and weighted third data, changes in one or more image or video attribute(s), in which the auxiliary information is conveyed through the changes. Of course, other claims and combinations are provided too.