An image processing method for harmonizing images acquired by a first camera and a second camera connected to a vehicle and arranged in such a way as their fields of view cover a same road space at different times as the vehicle travels along a travel direction is disclosed. The method includes: acquiring by a selected camera, a first image at a first time; selecting a first region of interest bounding a road portion from the first image; sampling the first region of interest; acquiring by the other camera, a second image in such a way that the road portion is included in a second region of interest; sampling the second region of interest; and determining one or more correction parameters for harmonizing images acquired by the first and second cameras, based on a comparison between the image content of the first and second regions of interest.