1. A method of forming a processed image using a plurality of images, each image generated by a respective sensor, comprising: dividing each image into a plurality of image regions; generating a contrast map for each image, each contrast map including a contrast value for each image region; applying a selection process to said contrast value for selecting an image region for use in said processed image; and forming said processed image with the selected image regions, wherein contrast values of contrast maps of respective first, second, and third sensors are compared together to form said processed image, the method further comprising: identifying contrast values from first and second sensor images to form an intermediate contrast map; wherein applying the selection process comprises applying a selection process to the contrast values of the intermediate contrast map and contrast values of a contrast map of a third sensor image.