For supporting correct and reliable operating displaying image data, wherein the image data may change over the time, the present invention suggests a reliable process, by use of which a secured image is generated based on a source image by generating at least one secured image part, wherein the secured image part is generated by combining a source image part of the source image with a corresponding secure pattern; and/or by monitoring displaying the secured image by detecting the corresponding secure pattern of the secured image part and by performing at least one of following: updating the detected secure pattern, checking the currentness or correctness of the detected secure pattern.