An image acquisition method with 6 times exposure using a common imaging system is presented. A “gray value-radiance” model has been built through the imaging process analysis, and the image gray value of each pixel changing in the relationship with the integration time has been acquired, ending with a infused 10 bits image with all the 6 multiple exposure image sequences. Using this method, an image with all the details of the scene is synthesized, enhancing the image sensitivity, and exhibiting a demonstrable effect in the dark target detection with the highlighted surroundings.