Light spots (prints) are not visible visually, such defects are poorly registered at the stage of cold rolling, and become visible only at the next stages, for example, after the galvanizing process. To identify such defects after the rolling process at the 4th and 5th class mills, it is necessary to carry out additional "rubbing" of rolled metal. It is necessary to find a way to detect this type of defect during the rolling process without reducing the productivity of the units. "1. Type of product – cold-rolled metal: 2. Strip thickness, mm: 0.25-3.2 3. Strip width, mm: 780-1650 4. Maximum speed, m/s: 30