The method involves determining a relevant spatial area (16) lying below a horizontal plane (14) from a viewing range of an optical sensor (12). A grayscale image is produced by the optical sensor, and a gray tone image includes a relevant image area that corresponds to the relevant spatial area. Gray values are summed or integrated for gaps of pixels within the relevant image area of the image. An upper envelope of column-wise integrated gray value signal is produced. Difference between the envelope and the gray value signal is formed for obtaining a one-dimensional profile. Independent claims are also included for the following: (1) a computer program with program code unit for detecting an object residing at a path (2) a computer program product with program code unit stored on a computer-readable data medium for detecting an object residing at a path (3) a device for detecting an object.
