Method for checking an optical security feature of a value document

A method for checking a prescribed optical security feature in or on a prescribed portion of a value document on the basis of pixel data of pixels of an image of the prescribed portion which are respectively associated with places in or on the portion and render optical properties of the value document at the places, comprising the steps:

• checking whether a first number of said pixels, or a first share of said pixels in the pixels of the image, whose pixel data, according to a first prescribed criterion, lie within a first reference region prescribed for the security feature exceeds a first minimum hit value prescribed for the security feature, and whether a first scatter of the pixel data of those pixels lying within the first reference region for the pixel data according to the first criterion exceeds a first minimum scatter value prescribed for the security feature, and
• in dependence on the result of checking, generating an authenticity signal which represents an indication of authenticity only when the first number or first share exceeds the first minimum hit value, and the scatter the first minimum scatter value.

A method for computer-aided checking of a prescribed security feature in or on a prescribed portion of a value document, comprising the steps:

• ascertaining a local condition value for the portion in dependence on properties of the value document at places lying within a prescribed edge region along at least a part of an edge of the portion or security feature and
• checking an authenticity or forgery criterion for the presence of an authentic security feature or a forgery in dependence on properties of the value document at places in the portion and on the local condition value.