Method and apparatus for inspecting transparent articles such as glassware for various types of defects, while conveying the articles past an optical inspection assembly. An article to be inspected is transported through an inspection station where it may undergo rotational and translational motion while being illuminated during an inspection interval. The inspection apparatus includes a video camera which provides output signals representative of the luminance of image elements, and video processing circuitry to derive line sum signals representative of the aggregate luminance of preselected scan lines. The line sum signals are further processed to discriminate streaks of brighter-than-normal or darker-than-normal pixels in a series of image frames. The user may establish window parameters to define an area of the article to be scanned for defects.