反射式電子紙之色彩特性化研究:以膽固醇液晶顯示器為例

Abstract

對於彩色圖像傳播而言，為確保影像與色彩的真實性，顯色媒介的色彩特性化是必要的工作之一。在本篇論文中將會介紹各種色彩特性化方法：物理模式、應用數值迴歸模式、利用內插法的對照表模式等。由於電子紙這種新型顯色媒介的興起，本論文以反射式膽固醇液晶顯示器為例，完成以上三種方法的色彩特性化的建立。此外，不同方法的可行性與精確度會被討論與檢驗。依照實驗結果與理論的比較，膽固醇液晶具有複雜的顯色物理機制，物理模式不適用於色彩特性化。又因膽固醇液晶顯示器的色彩空間與非設備從屬色彩空間(CIEXYZ)存在著高度非線性，較低階數值迴歸模式(20個多項式參數、729 training data)，其精準度約ΔE00_avg. ~1.4，仍大於一般的標準(∆E00<1)。對照表模式中不均勻的區間取樣(packing)是和膽固醇液晶顯示器本身顯色非線性的特性吻合，利用729點四面體內差法的對照表模式色彩特性化，將能夠達到高度的精確性(ΔE00_avg. =0.79)。

Colorimetric characterization of information devices is essential among the image communication. The upcoming electronic papers developed by the various ingenuities also need reliable color models. Therefore, general procedures: physical model, numerical model with regression, and look-up table with interpolation for characterizing any potential e-Paper technologies were introduced in this study. One of the commercial e-Paper products, cholesteric liquid crystal display (ChLCD) would be used as a test example to verify corresponding colorimetric characterization based on the three proposed methodologies. In addition, the feasibility and the fidelity of different manners would also be examined and discussed. In accordance with the experiment, physical model is impractical for ChLCD due to its inherent complex operating mechanism. Because of the nonlinearity between ChLCD color space and CIEXYZ space, the accuracy from a feasible numerical model with regression (20 polynomial terms and 729 training data) is reached to ΔE00_avg. =1.4, which is still larger than indistinguishable criterion (ΔE00<1). Compared with physical and numerical modeling, if the non-uniform packing is in response to the features of ChLCD itself, the colorimetric characterization utilizing 729 look-up tables with tetrahedral interpolation can offer the prediction with high fidelity (ΔE00_avg. =0.79).