Scan line noises attributed to small differences among responses of six detectors appear on LANDSAT MSS images. A linear transformation or a histogram equalization method is generally used to eliminate scan line noises from LANDSAT MSS images. However, these methods can not fully eliminate scan line noises, because of quantization errors. This paper describes a method to correct these residual scan line noises by adding random noises in order to improve the image quality. Random noises cancel the quantization errors and allow to make histograms continuously for each detectors.