Today, the digital camera has made it possible for people to take more "faithful" pictures easily. However, it is not always true that the subjective evaluation of image quality corresponds to the objective one. In some cases, adding noise and changing colors improve the subjective evaluation of image quality. The final goal of this study is to improve digital image quality. As a first step for constructing the image quality evaluation model, the effects of noise were observed in two psychological experiments. As a result, images to which appropriate noise was added might be evaluated higher than the original images on reality measures. Efforts to improve image quality must take into consideration human perception and manipulate physical factors appropriately. This research is a corporate-sponsored study.