1. A method for testing the reliability of error detection of an image inspection method using a computer, the image inspection method with the reliability test being a component of a printing process for a printing machine, the method comprising the following steps: producing a defective test image by superposing specific known error elements on an error-free reference image, the error elements constituting points or surfaces of maximally varied sizes and configurations; carrying out the image inspection method with the defective test image; comparing errors found in the image inspection method with an error set to be expected with the aid of the known error elements added to the test image; and evaluating the reliability of the image inspection method with the aid of a difference between the found and expected errors; and recalibrating the inspection method upon the reliability falling below a specific criteria.