1. An image processing device for detecting and suppressing shadows in a camera image of a surveilled scene, which camera image optionally shows static objects with static shadow regions and moving objects with dynamic shadow regions, the image processing device comprising a long-term module which is configured to generate a long-term reference image of the surveilled scene by evaluating a long-term observation of the surveilled scene; a mid-term module which is configured to generate a mid-term reference image of the surveilled scene by evaluating a mid-term observation of the surveilled scene; and a shadow detection module which is configured to process the camera image, using information technology, with the long-term reference image and the mid-term reference image in order to detect and suppress shadows.