Image understanding applications are assisted by a system that provides context for captured images. Devices in an image are capable of identifying themselves to the image capture device. The identifications may then be used to identify specific models needed to match possible devices in the image. In addition, the identifications may also be used to narrow the library of models needed to match possible devices in the image. Therefore, the library of possible objects may be narrowed to exclude most outdoor-oriented models or to include predominantly office-related objects. Narrowing the scope of possible models to consider can dramatically improve the effectiveness and efficiency of image understanding applications in these environments.