System , comprising: • a processing device (3; 3a, 3b); and • an exchangeable camera (5-1, 5-2; 5-1a, 5-2b) connected thereto for detecting a machine-readable security feature of a valuable document; • wherein the system is calibrated by means of processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b), which relate to characteristics of the processing device (3; 3a, 3b), and camera calibration data (kal1, kal2; kalla, kal2b), which relate to characteristics of the processing device (3; 3a, 3b) and of the camera (5-1, 5-2; 5-1a, 5-2b) connected thereto, • wherein the camera (5-1, 5-2; 5-1a, 5-2b) comprises a memory (7-1, 7-2) configured to store the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) and the camera calibration data (kal1, kal2; kalla, kal2b) relating to the system in which the calibration is carried out; and • wherein the processing device (3; 3a, 3b) comprises a memory configured to store the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) and the camera calibration data (kal1, kal2; kalla, kal2b) relating to the system in which operation for detecting a machine-readable security feature of the valuable document is carried out; wherein the processing device (3; 3a, 3b) is configured to calculate the camera calibration data (kal1, kal2; kalla, kal2b) - to be stored in the memory of the processing device (3; 3a, 3b) - of the system in which operation for detecting a machine-readable security feature of the valuable document is carried out, by weighting the camera calibration data (kal1, kal2; kalla, kal2b) stored in the memory (7-1, 7-2) of the camera (5-1, 5-2; 5-1a, 5-2b) with the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) stored in the memory (7-1, 7-2) of the camera (5-1, 5-2; 5-1a, 5-2b) and with the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) stored in the memory of the processing device (3; 3a, 3b) . • a processing device (3; 3a, 3b); and • an exchangeable camera (5-1, 5-2; 5-1a, 5-2b) connected thereto for detecting a machine-readable security feature of a valuable document; • wherein the system is calibrated by means of processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b), which relate to characteristics of the processing device (3; 3a, 3b), and camera calibration data (kal1, kal2; kalla, kal2b), which relate to characteristics of the processing device (3; 3a, 3b) and of the camera (5-1, 5-2; 5-1a, 5-2b) connected thereto, • wherein the camera (5-1, 5-2; 5-1a, 5-2b) comprises a memory (7-1, 7-2) configured to store the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) and the camera calibration data (kal1, kal2; kalla, kal2b) relating to the system in which the calibration is carried out; and • wherein the processing device (3; 3a, 3b) comprises a memory configured to store the processing device correction data (norm1, norm2; norm1a, norm1b, norm2a, norm2b) and the camera calibration data (kal1, kal2; kalla, kal2b) relating to the system in which operation for detecting a machine-readable security feature of the valuable document is carried out; <EOS>