人因工程應用在立體顯示器影像品質之實證與評估

Ergonomics Experimental Study and Evaluation on Image Quality of Autostereoscopic Displays

王珮嘉(Pei-Chia Wang)

指導教授 ： 黃雪玲

國立清華大學/工學院/工業工程與工程管理學系/博士(2013年)

https://doi.org/10.6843/NTHU.2013.00188

摘要

隨著顯示器科技的發展，立體顯示器已成為目前資訊時代的主流，但是現今的顯示技術仍存在某些問題需要解決。系統交錯殘影發生在左眼和右眼觀賞區域的漏光量，在裸眼立體顯示器中常常會嚴重影響視覺的品質，而3D 線索也是影響觀看者對於影像品質的重要因素，這些現象常造成使用者心理和生理的負擔。家用3D電視和電影正打入大眾市場，但是不適當的顯示器亮度和環境亮度將會影響觀看的影像品質。因此如何提高觀看者對於立體影像和觀看環境的舒適度是目前研究的重要課題。

本研究包含兩個實驗。第一個實驗探討交錯殘影和立體線索在barrier-type 和mirror-type立體顯示器對於觀看者的視覺疲勞度和影像品質的影響，此人因實驗共分為三個部分。第一部分探討mirror-type顯示器上的系統交錯殘影、陰影和線性透視，第二部份在分析人眼可接受的系統交錯殘影閾值，第三部份則比較barrier-type與mirror-type立體顯示器上的系統交錯殘影相對應閾值。研究結果顯示，系統交錯殘影、陰影和線性透視顯著影響觀看者對影像品質的評價，觀看mirror-type立體顯示器可以接受的系統交錯殘影閾值範圍為18.18%到22.98%；而barrier-type立體顯示器對應到mirror-type立體顯示器的系統交錯殘影閾值範圍為21.52%到30.46%，此數值高於mirror-type立體顯示器的可接受交錯殘影閾值範圍，並且發現呈現在barrier-type立體顯示器的影像內容，立體線索中的格紋和線性透視組合可提升影像品質的評價；由於本實驗中觀看立體顯示器僅10分鐘，因此並未顯著影響視覺疲勞。

第二個實驗延伸前一個實驗的範圍，探討顯示器亮度和環境照度對於靜態圖片和動態影片的影像知覺，兩種實驗影像在多視域的立體電視上播放：靜態圖片包含電腦繪圖和攝影的影像，動態影片含有真實生活和電玩動畫畫面，本實驗的受試者在不同水準的顯示器亮度和環境照度組合中，完成客觀疲勞度的量測和主觀舒適度的評量，實驗結果可得知觀看立體顯示器時的舒適亮度和照度環境。觀看靜態圖片時，當環境照度為55 Lux，較不會產生生理心理視覺疲勞度，而當顯示器亮度為34.2 cd/m2時，會有較佳的主觀舒適度和視覺績效；觀看動態影片時，在較亮（300 Lux）或全暗（0 Lux）的環境照度下，60 cd/m2的顯示器亮度會有較舒適的觀看環境。

本研究結果可當作立體顯示器的設計參考依據，其目的為使立體顯示器在市場中更具競爭力，並可提供給終端用戶，在使用上更為舒適。未來研究期望可以得到最佳的影像設計立體線索，探討更多會影響動態影片的因素，並建立品質良好的立體顯示器之準則。

關鍵字

系統交錯殘影 ； 立體線索 ； 影像品質 ； 疲勞度 ； 裸眼立體顯示器 ； 非裸眼立體顯示器 ； 顯示器亮度 ； 環境照度

並列摘要

3D displays have become the mainstream due to the development of display manufacturers. However, there have been some problems existed in current display technology. The crosstalk issue stemming from the leakage of light between viewing zones corresponding to the left and the right eyes is inevitable in some autostereoscopic displays and could sometimes be serious. 3D cues are also the major factors affecting viewers’ visual quality. These phenomena of 3D displays may increase viewers’ mental and physical loading. 3D TVs and movies have entered the mass market; however, the inadequate display luminance and ambient illumination might affect 3D image quality for viewers. As a result, it is a critical issue how to enhance the image quality of 3D images and the subject’s visual comfort on viewing 3D displays.

This study is composed of two experiments. The first research studied the effect of crosstalk and 3D cues upon viewers’ visual fatigue and image quality evaluation in both mirror-type 3D displays and barrier-type autostereoscopic displays. The first ergonomic experiment included three parts. First, the effect of system crosstalk, shadow, and linear perspective of 3D pictures in a mirror-type 3D display was verified. Second, an acceptable threshold level of system crosstalk was analyzed. Third, the fitting system crosstalk level in barrier-type autostereoscopic displays corresponding to that in mirror-type 3D displays was compared. The results showed that system crosstalk, shadow and linear perspective significantly affected image quality evaluation. The acceptable system crosstalk level in mirror-type 3D displays ranged from 18.18% to 22.98%. The fitting system crosstalk level in a barrier-type autostereoscopic display ranged from 21.52% to 30.46%, which was higher than that in a mirror-type 3D. In addition, the combination of 3D cues, grid and linear perspective, in a content of 3D images shown in a barrier-type autostereoscopic display could enhance the image quality evaluation. However, viewers replied neither visual fatigue nor visual discomfort when watching 3D pictures for only 10 minutes in this experiment.

The second experiment extended the first experiment to investigate whether screen luminance and ambient illumination have significant effects on the perception of 3D television imagery for static pictures and dynamic films. Two kinds of stimuli were shown on the multi-view stereoscopic display: the static pictures, which included computer-generated and photographic images, and the dynamic films, which contained real-life and animation images. In each treatment with a different level of screen luminance, subjects finished psychophysical and physiological measurements and subjective comfort evaluation. The results showed the suitable watching condition of luminance and ambient for 3D viewing experience. When subjects viewed 3D static pictures, ambient illumination of 55 Lux could produce the lower psychophysical visual fatigue, and screen luminance of 34.2 cd/m2 could cause better subjective comfort evaluation and visual discrimination performance. However, when subjects watched 3D dynamic films, screen luminance of 60 cd/m2 under brighter (300 Lux) or dark (0 Lux) ambient illumination was the better viewing condition.

The results of this study could be served as a reference for the design of 3D displays. In order to promote the 3D display in the market, industry will need to tackle all of these challenges to support content creators and provide features and ease of use that end users require. For the further study, it is expected to obtain the optimal 3D cues, and the various impactful viewing 3D factors of dynamic films to build up guidelines for a qualified autostereoscopic and stereoscopic display.

並列關鍵字

system crosstalk ； 3D cue ； image quality ； fatigue ； autostereoscopic display ； stereoscopic display ； screen luminance ； ambient illumination

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