This patent document relates generally to steganography and digital watermarking. One claim recites, in a watermark detector, a method of decoding auxiliary information encoded encoding in an image or video. The method includes: receiving data representing the image or video, wherein the data comprises first data corresponding to a first color channel, second data corresponding to a second color channel and third data corresponding to a third color channel; weighting the first data, the second data and the third data according to at least the following two factors: i) a color direction biased toward an anticipated embedding direction; and ii) anticipated image or video distortion introduced to the first data, second data or third data through scanning or signal processing; and determining from weighted first data, weighted second data and weighted third data, changes in an image or video attribute, in which the auxiliary information is conveyed through the changes to sample values representing the image or video. Of course, other claims and combinations are provided too.