1. An imaging system mountable in a vehicle, comprising: a primary camera, which, when mounted inside the vehicle, is configured to acquire a first image through a window of the vehicle, wherein the first image is an image of an environment outside the vehicle; a secondary camera, which, when mounted inside the vehicle, is configured to acquire a second image; wherein a first region of the window is subtended by a field of view of the primary camera and a second region of the window is subtended by a field of view of the secondary camera, wherein the first region and the second region of the window overlap at least in part; a processor configured to process the second image to detect at least one suspected obstruction on a surface of the window, and responsive to detection of the at least one suspected obstruction on a surface of the window in the second image, the processor is configured to process the second image to determine an image coordinate of the at least one suspected obstruction in the first image.