1. An image-processing device for carrying out an object segmentation, comprising: means for executing the object segmentation through comparison of a camera image to a received reference image of a surveillance scene; a learning device for generating the scene reference image, said learning device being configured to generate the scene reference image through evaluation of a medium-term and/or long-term observation of the surveillance scene that occurs in a situation selected from the group consisting of occurring over a time period of longer than one day, occurring over a time period which includes several states of the reference scene, and both, wherein said learning device is configured to generate a scene model, wherein the scene model is a model of a scene that comprises artificial model objects in the form of a virtual world, and wherein said scene model is in the form of a multi-mode scene model and individual modes of said multi-mode scene model are distinguished through different states of the surveillance scene, and wherein the states of the surveillance scene differ with regard to one or more of parameters selected from the group consisting of relative position of a surveillance camera, relative orientation of a surveillance camera, absolute position of a surveillance camera, and absolute orientation of the surveillance camera, wherein the scene model forms the basis for the generation of the scene reference image.