Cell phones and other portable devices are equipped with a variety of technologies by which existing functionality is improved, and new functionality is provided. Some aspects relate to imaging architectures, in which a cell phone's image sensor is one in a chain of stages that successively act on instructions/data, to capture and later process imagery. Other aspects relate to distribution of processing tasks between the device and remote resources (“the cloud”). Elemental image processing, such as filtering and edge detection—and even some simpler template matching operations—may be performed on the cell phone. Other operations are referred out to remote service providers. The remote service providers can be identified using techniques such as a reverse auction, through which they compete for processing tasks. Other aspects of the disclosed technologies relate to visual search capabilities, and determining appropriate actions responsive to different image inputs. Still others concern metadata generation, processing, and representation. A great number of other features and arrangements are also detailed.