The invention relates to an article-processing device comprising a conveyor (2) for moving articles (1) in series and on edge, a camera (3) for taking a digital image (4) of each article (1), a data processor unit for performing processing on the pixels of the digital image (4), and means for inspecting/monitoring the quality of the digital images (4), said article-processing device being characterized in that: said conveyor has a back wall (9) of a dark color; said camera (3) takes a digital image (4) within which the article (1) lies against a background (7) corresponding to said back wall (9); and said inspection/monitoring means scan rows of pixels in order to extract, for each scanned row, a pixel having a light intensity extremum, and detect contrast indicative of degradation of the quality of the digital images (4). The invention also relates to a sorting machine including such a device, and to an inspection/monitoring method.