1. An imaging system suitable for use in a vehicle, said imaging system comprising: an imaging sensor comprising a two-dimensional array of photosensing elements, said two-dimensional array comprising a plurality of sub-arrays, wherein each sub-array of said plurality of sub-arrays comprises four photosensing pixels comprising a first photosensing pixel, a second photosensing pixel, a third photosensing pixel and a fourth photosensing pixel; wherein said four photosensing pixels of each said sub-array are arranged in a 2×2 matrix with said fourth photosensing pixel disposed diagonally to said first photosensing pixel and with said third photosensing pixel disposed diagonally to said second photosensing pixel; wherein one of (a) a red-light transmitting spectral filter is disposed at said first photosensing pixel whereby said first pixel of each said sub-array primarily senses red visible light and wherein an IR transmitting spectral filter is disposed at said fourth photosensing pixel whereby said fourth pixel of each said sub-array primarily senses infrared radiation and (b) a red-light transmitting spectral filter is disposed at said first photosensing pixel whereby said first pixel of each said sub-array primarily senses red visible light and wherein an IR transmitting spectral filter is disposed at said third photosensing pixel whereby said third pixel of each said sub-array primarily senses infrared radiation; wherein said imaging sensor is configured to be disposed at a vehicle equipped with said imaging system and wherein, when said imaging sensor is disposed at the equipped vehicle, said imaging sensor has a field of view forwardly of the equipped vehicle through a windshield of the equipped vehicle; an image processor for processing image data captured by said imaging sensor, wherein said image processor processes the output of each said sub-array to determine at least one of an infrared component of the imaged scene and a visible light component of the imaged scene; wherein, responsive at least in part to processing by said image processor of the output of each said sub-array and with said imaging sensor disposed at the equipped vehicle and viewing forwardly through the windshield, said imaging system is operable to detect at least one of (i) a headlight of a vehicle ahead of the equipped vehicle, (ii) a taillight of a vehicle ahead of the equipped vehicle, (iii) a lane marking and (iv) a traffic sign.