A system, comprising: a mobile device camera configured to capture images; one or more environment sensors configured to detect movement of the camera; a data processing apparatus; and a memory storage apparatus in data communication with the data processing apparatus, the memory storage apparatus storing instructions executable by the data processing apparatus and that upon such execution cause the data processing apparatus to perform operations comprising: accessing, for each of a plurality of images captured by the mobile device camera, data indicative of movement of the camera at a time at which the camera captured the image; selecting, from the plurality of images, a particular image for analysis based on the data indicative of the movement of the camera for each image; analyzing the particular image using a composite coarse classifier to detect presence of multiple different classes of objects depicted in the particular image, wherein analyzing the particular image using the composite coarse classifier comprises initiating analysis by the composite coarse classifier periodically based on a processing rate, the processing rate adjusted based on whether presence of one or more classes of objects has been detected in one or more images analyzed by the coarse classifier over a previous time period; determining, using the composite coarse classifier, a confidence score for the multiple different classes of objects simultaneously; analyzing the particular image to recognize one or more objects depicted in the particular image in response to determining the presence of the multiple different classes of objects in the particular image; and presenting content related to the one or more recognized objects. a mobile device camera configured to capture images; one or more environment sensors configured to detect movement of the camera; a data processing apparatus; and a memory storage apparatus in data communication with the data processing apparatus, the memory storage apparatus storing instructions executable by the data processing apparatus and that upon such execution cause the data processing apparatus to perform operations comprising: accessing, for each of a plurality of images captured by the mobile device camera, data indicative of movement of the camera at a time at which the camera captured the image; selecting, from the plurality of images, a particular image for analysis based on the data indicative of the movement of the camera for each image; analyzing the particular image using a composite coarse classifier to detect presence of multiple different classes of objects depicted in the particular image, wherein analyzing the particular image using the composite coarse classifier comprises initiating analysis by the composite coarse classifier periodically based on a processing rate, the processing rate adjusted based on whether presence of one or more classes of objects has been detected in one or more images analyzed by the coarse classifier over a previous time period; determining, using the composite coarse classifier, a confidence score for the multiple different classes of objects simultaneously; analyzing the particular image to recognize one or more objects depicted in the particular image in response to determining the presence of the multiple different classes of objects in the particular image; and presenting content related to the one or more recognized objects. accessing, for each of a plurality of images captured by the mobile device camera, data indicative of movement of the camera at a time at which the camera captured the image; selecting, from the plurality of images, a particular image for analysis based on the data indicative of the movement of the camera for each image; analyzing the particular image using a composite coarse classifier to detect presence of multiple different classes of objects depicted in the particular image, wherein analyzing the particular image using the composite coarse classifier comprises initiating analysis by the composite coarse classifier periodically based on a processing rate, the processing rate adjusted based on whether presence of one or more classes of objects has been detected in one or more images analyzed by the coarse classifier over a previous time period; determining, using the composite coarse classifier, a confidence score for the multiple different classes of objects simultaneously; analyzing the particular image to recognize one or more objects depicted in the particular image in response to determining the presence of the multiple different classes of objects in the particular image; and presenting content related to the one or more recognized objects.