FIELD: this relates to thermography. SUBSTANCE: half-tone image created on thermographic film by means of thermographic method has at least two kinds of half-tone dots which are respectively of different dimensions. Beside that, at least two kinds of half-tone dots can have different optically effective structures and particularly diffraction structure which causes diffraction or interference of structural screen. In this case, image is built of dots with dull surface and of dots with lustrous surface and this allows for producing not only common half-tone or color solution of half-tone image but also to configure half-tone image with various lustrous effects, etc. This allows for producing special half-tone images which are very difficult to falsify and they can not be reproduced by means of color copying apparatus. Half-tone images are especially suitable for application for example in function of protection signs on valuable documents such as bank-notes, credit cards, identification cards which someone can try to falsify by means of modern color copying apparatus. EFFECT: higher efficiency. 8 cl, 3 dwg
