FIELD: roller or laser welding. SUBSTANCE: line specimen passing through edge is projected by means of projection device and recorded by camera. Recorded image is analyzed, and conclusion is made by line form about clearance between sheets or about form of edges. Several lines are projected at different light intensity. This makes it possible to select line in image not too weak and not too intensive when processing the recorded image and in case of varying characteristic of sheet reflection. Edge control apparatus includes device for formation of light linear specimen and receiving device. Data processing device is capable to line selection by brightness of controlled or reflected radiation. EFFECT: true evaluation of image. 14 cl, 2 dwg
