The display of correct and reliable operating image data which may change over the time is correctly and reliably displayed. A secured image is generated based on a source image by generating at least one secured image part. The secured image part is generated by combining a source image part of the source image with a corresponding secure pattern. The displaying of the secured image is monitored by detecting the corresponding secure pattern of the secured image part, updating the detected secure pattern, checking the currentness or correctness of the detected secure pattern
