隨著顯示技術的進步，3D電影所帶來的視覺震撼，透過立體投影機或大尺寸立體電視，由電影院走入家庭。不過由於觀看3D影像會產生一些不舒適感，因此，大尺寸LCD的3D視覺舒適度是非常值得研究的課題。本研究的目的在於透過一系列的心理物理實驗，找出在不同視差條件下的視覺舒適範圍。根據本研究所獲得的立體舒適視差閾值，將視差過大的立體影像調整至視差較小的視覺舒適範圍內，應該可以降低立體影像的不舒適感。
基於上述的研究目的，提出六個研究方向。視覺舒適的視差範圍、可同時融合背景與前景的視差範圍、視差範圍受前景或背景位置的影響、將影像背景模糊化，擴大舒適的視差範圍、瞳距的大小是否會影響視覺舒適的視差範圍、不同影像內容的舒適視範圍是否一致。實驗結果顯示：(1).在收斂拍攝的情況下，前景與背景的視角差範圍在1.5度視角內是具有立體感且最舒適的。(2).前景與背景的視角差範圍在大約0.8度左右是人眼可以同時融合背景與前景的視差範圍。(3).視差範圍會受到前景或背景位置的影響而有些微的不同。(4)把背景做輕微的模糊處理是有幫助擴大舒適的視差範圍。(5).小瞳距的受測者舒適的視差範圍是比一般人還要小的。(6).在使用收斂拍攝法的時候，不同影像內容的舒適視範圍可能會有些微的不同。
由於本論文僅有使用單一型號之立體顯示器，在後續的研究中希望能夠針對不同尺寸之顯示器與不同的觀看距離做相關的探討，希望將來可以找出一個適當的模型用來改良觀看3D立體顯示器的舒適度。

Display technologies improve greatly in recent years. Large size 3D TVs are now bringing 3D immersive experience from cinemas to our living room. However, many customers still worry about 3D visual discomfort issue. Methods for improving visual comfort of large format 3D TVs therefore are worth studying. The aim of the study is to investigate visual comfort range of a large-size 3D LCD display for depth- image-based algorithms to scale parallax angles into the range.
The study tried to answer six questions including： What is the visual comfort range? What is the fusion limit? Is the comfort range depended on the parallax of background or foreground? Can the comfort range be extended by background burring? Is the comfort range for small interpapillary-distance observers is different from normal observers? Is the comfort range is image dependent? A series of psycho-visual experiments were conducted to answer those questions. The results show that： (1) For a toed-in 3D image, the visual comfort range is about 1.5o visual disparity angles from a background to a foreground object. (2) The fusion limit is about 0.8 o visual disparity angles. (3) The comfort ranges for different background or foreground parallax is similar. (4) Background blurring would extend the comfort range. (5) The comfort range of small interpapillary-distance observers is smaller than normal observers. (6) The comfort range is image dependent for toed-in 3D images but independent for parallel 3D images.
The study evaluated 3D visual comfort for only one viewing distance. More viewing conditions should be tested for deriving a versatile model to improve 3D visual comfort of large-size 3D LCD displays.

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