A banknote validator, comprising: a banknote path formed within an interior of the banknote validator to transport a banknote from an opening of the banknote path through an interior of the banknote validator; a banknote imaging zone defined within a portion of the banknote path, the banknote imaging zone including a reflective region in a first portion of the banknote imaging zone, and a dark region in a second portion of the banknote imaging zone; and an image sensor configured to capture one or more images of at least a portion of the banknote imaging zone, wherein the image sensor is further configured to capture one or more baseline images of the banknote imaging zone while the banknote validator is in an idle state, wherein the reflective region and the dark region of the banknote imaging zone provide a background for the one or more images, and further comprising: a processor configured to: perform image processing of at least one of the one or more captured images; and determine that, as a result of the image processing of the at least one of the one or more captured images, a foreign object is present in the banknote imaging zone, wherein, to perform at least part of the image processing, the processor is further configured to: compare the at least one of the one or more captured images with the one or more baseline images; and identify the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object. a banknote path formed within an interior of the banknote validator to transport a banknote from an opening of the banknote path through an interior of the banknote validator; a banknote imaging zone defined within a portion of the banknote path, the banknote imaging zone including a reflective region in a first portion of the banknote imaging zone, and a dark region in a second portion of the banknote imaging zone; and a reflective region in a first portion of the banknote imaging zone, and a dark region in a second portion of the banknote imaging zone; and an image sensor configured to capture one or more images of at least a portion of the banknote imaging zone, wherein the image sensor is further configured to capture one or more baseline images of the banknote imaging zone while the banknote validator is in an idle state, wherein the reflective region and the dark region of the banknote imaging zone provide a background for the one or more images, and further comprising: a processor configured to: perform image processing of at least one of the one or more captured images; and determine that, as a result of the image processing of the at least one of the one or more captured images, a foreign object is present in the banknote imaging zone, wherein, to perform at least part of the image processing, the processor is further configured to: compare the at least one of the one or more captured images with the one or more baseline images; and identify the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object. a processor configured to: perform image processing of at least one of the one or more captured images; and determine that, as a result of the image processing of the at least one of the one or more captured images, a foreign object is present in the banknote imaging zone, wherein, to perform at least part of the image processing, the processor is further configured to: compare the at least one of the one or more captured images with the one or more baseline images; and identify the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object. compare the at least one of the one or more captured images with the one or more baseline images; and identify the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object.