To compensate density of abnormal lung field for density of normal lung field, used each cellulose paper calculated sensitometry and contrast. As apply clinic part to the result: We are able to compensate density of abnormal lung that is pleural effusion atelectasis, etc for normal lung. We believe this method is good one because the method is simple to change exposure and the material is cheap enough to be accessible to every one and easily buyable and we need not be afraid of loss of image quality.