A device, such as a cell phone, uses an image sensor to capture image data. The phone can respond to detection of particular imagery feature (e.g., watermarked imagery, barcodes, image fingerprints, etc.) by presenting distinctive graphics on a display screen. Such graphics may be positioned within the display, and affine-warped, in registered relationship with the position of the detected feature, and its affine distortion, as depicted in the image data. Related approaches can be implemented without use of an image sensor, e.g., relying on data sensed from an RFID device. A variety of other features and arrangements are also detailed.