多階人眼視覺模型與視覺特性於顯示器元件上的應用

Abstract

顯示器元件在設計及規格之制定上通常會以人眼的視覺感知為基礎，因此人類的視覺特性在顯示器的發展上扮演著重要的角色。本論文主要的研究方向有二：一是評估顯示器的影像品質，傳統的評價方法只單純地考慮客觀的物理參數，然而人眼的主觀感知是決定影像品質的關鍵之一，所以客觀的評價結果常常與主觀的感知不相符。因此本論文提出以一多階視覺模型為基礎的影像品質量化方法。此方法的最大優點之一就是評估的結果與人眼的主觀感知相符，配合CRT及LCD等的顯示器模型，找出gamma、對比度及亮度等參數與影像品質之關係，由評估的結果可以對主觀的影像品質制定出最佳化的顯示參數，提供顯示器設計者一個設計依據。 另一方面是研究人眼對顯示器相鄰畫素亮度均勻性容忍度之研究，造成顯示器畫素亮度不均勻的主要因素之一為驅動IC的漏電流誤差，藉由在本論文中設計的主觀視覺實驗，可以了解人眼對顯示器畫素亮度不均勻性與亮度之關係，實驗結果可以應用於制定驅動IC誤差容忍度規格的參考。

Human perception is the basis for defining specification of display devices. Consequently, human visual characteristics play an important role in the development of display devices. There are two subjects studied in this thesis. One is display image quality evaluation. Conventional image quality evaluation only takes objective physical parameters into consideration. However, image quality is mainly determined by human perception. Objective evaluative results usually do not match with subjective human perception. An image quality evaluative method based on a multi-scale human visual is proposed in this thesis. The major advantage of this evaluative method is that the results are well correlated with subjective human perception. The dependence of gamma, contrast ratio and brightness on image quality is specified. As a consequence, optimal display parameters can be specified. The leakage current of driving IC causes the non-uniformity in brightness on display devices. The tolerance of human vision on brightness uniformity of adjacent pixels on display devices is conducted via a psychophysical experiment. Therefore, the human acceptable brightness non-uniformity could be specified according to the subjective visual experimental results on tolerance of brightness difference. The human acceptable tolerance can then be utilized to specify the characteristics of driving IC to achieve adequate uniformity.