A novel image coloration fusion method in oRGB color space is presented for the enhancement of thermal infrared and visible night-vision images. We chose to construct a pseudo-color image and to execute color transfer in the same oRGB color space because this new space is reasonably simple, has intuitive axes, and is well-suited for computational applications. In order to preserve detail information from the source images in the final coloration image, the luminance component of the pseudo-color image is assigned to the fused image by a multi-scale top-hat transform. The two color components of the pseudo-color image are constructed according to the differences between the dual-band images and the color statistics of the reference image. To avoid gray-scale compression or over-saturation that can be easily caused by the linear color transfer method, we applied histogram matching rather than linear transformation to the two color components in the color transfer process. Experiments show that our method produces a coloration image with a more natural color distribution. Furthermore, visual features such as salient features and overall brightness and contrast are superior to those produced by other methods.