想要獲得較偏好的影像階調，最常使用的方法便是直接調整影像的Gamma值。但這個較偏好的影像Gamma值並非為一固定值，且調整範圍也會因影像內容不同而有改變，至目前為止，尚未有文獻能針對自然影像預測最佳的Gamma值調整範圍。本研究即透過心理物理實驗方式，建立自然影像階調分佈特徵與人眼視覺最偏好影像亮度特性兩者之間的關係。並藉由影像亮度的特性與顯示器Gamma值的對應關係，以最偏好的影像平均亮度，透過二分逼近法方式，反推回自然影像之最佳Gamma值調整範圍，並可有效獲得約70%的預測準確率。
Gamma adjustment is a usual tool for acquiring preferable image tone. The optimal gamma value would depend on image content. There is little knowledge about how to acquire the optimal value so far. This study tried to explore the relationship between optimal Gamma value and preferable image brightness by pair comparison method. It is found that the optimal Gamma could be derived from preferable image brightness which could be predicted from experimental data. Ultimately, an optimal Gamma value was derived by the mapping function between display characteristic and image brightness at about 70% correction rate for Gamma prediction.
