視知覺實驗的顯示器迦瑪校正：理論與實務

Gamma Correction for Monitors Used in Psychological Experiments

顯示器是大多數心理學實驗所採用的刺激呈示器（stimulus display）。然而其輸出強度與程式人員所指定的電壓輸入值之間的關係卻是非線性的，這個現象會嚴重影響以刺激的強度或對比值為實驗變項的實驗結果。在工程界將各種矯正此非線性行為的措施稱為迦瑪校正。本文解說了顯示器的非線性行為的產生原因，以及如何以軟體手段予以精密矯正的方法。實際做螢幕校正工作時所需的工具程式亦以可由網路下載的方式提供有此需要的人士使用。

Color monitors are widely used by experimental psychologists as a major visual display device. There is an inherent nonlinear output property of the monitor that can greatly affect the results of experiments where the intensity level or contrast of the stimuli is of any significance. Measures taken to ameliorate this problem have been generally called “Gamma correction” in engineering fields. The physical cause of such nonlinearity, together with the correction procedures by software to the precision for experimental purposes are discussed in this article. Downloadable software tools and instructions are also provided.