Targeting negative effects such as clarity and contrast degradation and color distortion of images acquired in hazy weather， underwater， and in nighttime environments， a two-stage image restoration method using an improved atmospheric scattering model is proposed. A global compensation coefficient is introduced into the traditional atmospheric scattering model to obtain an improved atmospheric scattering model； the two-stage image restoration method based on this model consists of two stages. First， a degraded image is fed to the improved atmospheric scattering model to obtain a coarse restored image. The grayscale world algorithm is then used to determine the albedo of this coarse restored image. Second， the albedo and output image of the first stage are fed to the improved atmospheric scattering model to obtain the final restored image. Experimental results indicate that the proposed method can avoid the problems of color distortion and dark tones in the restored images and has good applicability. The method can effectively achieve image dehazing， underwater image restoration， and night image enhancement. The proposed method achieves excellent results in both quantitative and qualitative experiments compared with state-of-the-art methods.