Abstract: The invention relates to a forge-proof document comprising a security feature in the form of a perforation pattern which displays gray tones when viewed against a bright background, wherein the document is manufactured from a material which transmits light to a limited extent, at least some of the perforations forming part of the perforation pattern extend over only a part of the thickness of the document at the position of the perforation, and the thickness of the remaining part of the document at the position of the perforation is modulated in accordance with the image to be displayed. The invention also relates to such a document comprising a security feature in the form of a perforation pattern which displays gray tones when viewed against a bright background, wherein at least some of the perforations forming part of the perforation pattern extend at an angle differing from 90° relative to the main plane of the document.