1. A method for enhancing an image, the method comprising: estimating unsharpness of the image; determining a protection level of at least one pixel in the image based on the unsharpness, wherein the protection level is associated with an amount of modification for enhancing the image at a low light condition or a certain fog density; and modifying a value of the at least one pixel to enhance the image, an amount of the modifying being determined at least in part based on the protection level and an adjusted deviation degree of atmospheric light.