1. A method for fusing two images comprising: separately receiving (a) intensity values of a thermal image and (b) intensity values of a visual image; separately adjusting contrast of (a) the intensity values of the thermal image and (b) the intensity values of the visual image; combining (a) contrast adjusted intensity values of the thermal image and (b) contrast adjusted intensity values of the visual image, to form combined brightness values; separating a target region from a background region in the thermal image; assigning hue values to the target region in the thermal image, after separating the target region from the background region in the thermal image; and displaying a fused image, based on the assigned hue values obtained in the thermal image and the combined brightness values; wherein assigning hue values to the target region in the thermal image includes: computing an ambient threshold value for the target region, assigning a hue value of zero to a pixel from the thermal image, if the pixel has an intensity value less than the ambient threshold value, and assigning a hue value of non-zero to a pixel from the thermal image, if the pixel has an intensity value greater than or equal to the ambient threshold value.