1. A multi-camera imaging-based bar code reader for imaging a target bar code on a target object, the bar code reader comprising: a housing supporting one or more transparent windows and defining an interior region, a target object being presented in relation to the housing for imaging a target bar code; an imaging system including a plurality of cameras wherein each camera is positioned within the housing interior region and defines a field of view which is different than a field of view of each other camera of the plurality of cameras and combine to form a bar code reader field of view, each camera including a sensor array; and an image processing system comprising a processor having a stored program for evaluating images from a subset of cameras that define the bar code reader field of view to determine a presence of a target object and once a target object is detected, to activate an additional one or more cameras for use in decoding a barcode.