In low light or night conditions

the signal-to-noise ratio is low and the details are not clear in color images. Although near infrared cameras can get image with rich texture

the edge details lacks color under this condidtion. In order to get a clear color image

we propose an improved bilateral-filter image-fusion algorithm in low light conditions in this paper. In the algorithm

the kernel function is re-designed using the power function to replace the exponential function

and canceling the design parameter. In order to avoid image texture and edge smoothing

the large difference of pixels is used as a pixel similarity in the color image and near IR image for image fusion. By using of a color image and an infrared image

this method and several other typical fusion methods are tested under low light condition. The experimental results show that the color images have higher definition compared with other fusion algorithm. The color is more close to the source image. The computation speed is more than 6 times compared faster to the Eric.P algorithm.