Color the night : applying daytime colors to nighttime imagery

We present a method to give (fused) multiband night-time imagery a natural day-time color appearance. For input, the method requires a false color RGB image that is produced by mapping 3 individual bands (or the first 3 principal components) of a multiband nightvision system to the respective channels of an RGB image. The false color RGB nightvision image is transformed into a perceptually decorrelated color space. In this color space the first order statistics of a natural color image (target scene) are transferred to the multiband nightvision image (source scene). To obtain a natural color representation of the multiband night-time imagery, the compositions of the source and target scenes should resemble each other to some degree. The inverse transformation to RGB space yields a nightvision image with a day-time color appearance. The luminance contrast of the resulting color image can be enhanced by replacing its luminance component by a grayscale fused representation of the three input bands