Examples of the present disclosure relate to methods for performing image processing. In one such example, a model of an environment is stored. Image data representative of a captured observation of the environment is obtained and the image data is processed using an object classifier to determine whether one or more objects belonging to a plurality of predetermined classes of objects is present in the environment. The stored model is updated based on the processing. In response to determining at least one of the one or more objects is present, object class characteristic data indicative of a characteristic of the at least one object that is determined to be present is retrieved and a probability of change associated with the at least one object is determined on the basis of the object class characteristic data. The updating of the stored model is adjusted based on the determined probability of change.