In 1990's, Digital Imaging and Communication in Medicine (DICOM) standard proposed the Gray-scale Standard Display Function (GSDF) as a calibration tool for consisting the output gradation characteristics for medical images. However, in the previous paper, we showed that the GSDF could not satisfy the perceptual linearization in encountered during a clinical diagnosis in a hospital due to the eye response model by Barten. In this study, we propose a new method for obtaining an ideal shape of the calibration curve corresponding to the various observation environments, using the minimum perceptible luminance difference.