A display and/or operating device for controlling machines includes a projection device for projecting an image onto a projection area, an acquisition device for scanning the same projection area, and a control computer for controlling the projection device and the acquisition device. The present invention is distinguished by the fact that, by the acquisition device and the control computer, an analysis of the same projection surface can be carried out, and that the content of the image to be projected can be controlled by the control computer as a function of the result of the analysis of the same projection area.