液晶顯示器的顏色偏移分析和影像品質評估

Abstract

本論文主要的研究方向有二：一是分析液晶顯示器的顏色偏移現象，探討顏色偏移成因及誤差容忍範圍。影響顏色偏移最主要的因素為液晶面板電壓對穿透率頻譜圖形變化不規則所造成的。若LCD要達到良好的色彩重現性，顏色之色度座標偏移量必須小於0.005個xy色度空間單位，此時色差約為1□E*uv左右，不必另外加修正模型即可重現原來之顏色。 另一方面則是評估顯示器的影像品質，主要分為解析度及色彩表現兩方面來探討。在解析度方面，若CRT的Spot size和LCD的Pixel pitch相同時，CRT的解析度優於LCD；但就現階段技術而言，LCD的解析度仍優於CRT。此外，LCD在相同畫素密度下，不同畫素排列所顯示的影像品質則以Delta排列為最佳，而以Stripe為最差。在色彩評估方面，本論文利用彩度及一主觀評價Q-factor來評估顯示器的顯色能力和視角大小，此方法比以往單用亮度及對比度來評估影像品質更為嚴謹且接近人眼的評價。

Analyses color-shift of LCD and calculation the acceptable color deviation is the first subject studied in the thesis. The key parameter that directly affects the color-shift is voltage-dependant spectrum profile of LC cell. If LCD’s color deviation is smaller than 0.005 xy colorimetric space unit, color can be reproduced very well without using correction models. Evaluation of resolution and color performance of displays’ image quality is the next subject researched. If CRT’s spot size is equal to LCD’s pixel pitch, the resolution of CRT is superior to LCD. According to the analyses, LCD’s resolution is also influenced by the pixel arrangements. Therefore, delta arrangements show the higher resolution than others do. In the part of color performance, chroma and an evaluation method “Q-factor” is proposed to evaluate image quality and viewing angle of displays. The proposed method is more serious and subjective than luminance and contrast before.