Enhancing thermal video using a public database of images

摘要

We presented a system to display nightime imagery with natural colors using a public database of images. We initially combined two spectral bands of images, thermal and visible, to enhance night vision imagery, however the fused image gave an unnatural color appearance. Therefore, a color transfer based on look-up table (LUT) was used to replace the false color appearance with a colormap derived from a daytime reference image obtained from a public database using the GPS coordinates of the vehicle. Because of the computational demand in deriving the colormap from the reference image, we created an additional local database of colormaps. Reference images from the public database were compared to a compact local database to retrieve one of a limited number of colormaps that represented several driving environments. Each colormap in the local database was stored with an image from which it was derived. To retrieve a colormap, we compared the histogram of the fused image with histograms of images in the local database. The colormaps of the best match was then used for the fused image. Continuously selecting and applying colormaps using this approach offered a convenient way to color night vision imagery.