After fixing on the divergent angle,peak power of laser pulse,parameters of received optical system and the geometrical configuration betweeh laser and received optical system, a faint target image of longer range with higher resolution obtained by active imaging system is constrained by imaging and processing technologies. With longer range and limited laser energy, it is impossible to illuminate the entire scene at once, and the illuminance obtained by each receiver pixel of CCD can not achieve an adequate level. In order to increase the imaging range of imaging system with given per-pulse laser en ergy, and to reduce atmospheric turbulence effects on image resolution, multi pulses may be employed to obtain image data over the whole scene and radiometric conceptions are used to establish the maximum scene illumination region during each exposure. A unique multiframe postprocessing technique is investigated in this paper. It is shown that in the presence of atmospheric turbulence and coherent speckle effects, this approach can produce superior results to conventional scene flood illumination.