1. A method comprising: defining one or more protected regions of a scene that correspond to one or more sensitive portions within the scene; determining that a coordinate location representing a pixel within the scene lies within at least one of the one or more protected regions; receiving a temporal series of digital images of the scene; generating a set of pixel values and pixel value frequencies for the pixel as the pixel reoccurs at a same coordinate location for each received digital image in the temporal series of digital images; receiving a subsequent digital image of the scene, wherein the subsequent digital image comprises a subsequent pixel value for the pixel at the same coordinate location within the scene; comparing the subsequent pixel value with the set of pixel values and pixel value frequencies; and based on the comparing, determining whether to substitute the subsequent pixel value with a different pixel value.