| 摘要 |
A method includes checking a specified security feature of a value document which is present in a specified security-feature region of the value document. The security feature includes captured pixel data which describe spatially resolved with a specified optical spatial resolution, an optical image at least of the security-feature region of the value document, and there are captured ultrasound data which describe an ultrasonic property of the value document at least in the security-feature region, spatially resolved with a specified ultrasonic spatial resolution. The ultrasonic spatial resolution is lower than the optical spatial resolution. From the pixel data there are established first reduced-resolution pixel data for reduced-resolution pixels of the first reduced-resolution image which describe a reduced-resolution optical image at least of the security-feature region of the value document, whose optical spatial resolution corresponds to the ultrasonic spatial resolution. |
