An imaging device collects color image data to facilitate distinguishing crop image data from background data. A definer defines a series of scan line segments generally perpendicular to a transverse axis of the vehicle or of the imaging device. An intensity evaluator determines scan line intensity data for each of the scan line segments. An alignment detector identifies a preferential heading of the vehicle that is generally aligned with respect to a crop feature, associated with the crop image data, based on the determined scan line intensity meeting or exceeding a maximum value or minimum threshold value. A reliability estimator estimates a reliability of the vehicle heading based on compliance with an intensity level criteria associated with one or more crop rows.