基於底色移除法對LCD的色彩校正

隨著科技的進步，液晶顯示器已經逐漸取代了陰極射線管的顯示器，成為市場上的主流。在市場的需求中，因為輸入相同的影像訊號在不同的顯示器上，常會有不同的色彩再現，這容易讓人產生困擾的。因此，為了要將輸入的影像訊號，在不同的顯示器上有相同的色彩再現，必須要做色彩的校正。當要做色彩校正之前，需要先了解色彩管理系統是如何控制輸入的訊號，經過顯示器時讓色彩校正到預期的顏色。在本研究中，為了要做色彩校正，首先必須了解顯示器的色彩特性，以及適合顯示器色彩特性的逆運算模型。由於，一般顯示器的色彩特性中存在有色彩通道的相互作用和背光漏光的問題，本研究曾就考慮此兩問題，利用GOG模型的電光轉換，以及印刷常用的底色移除法提出一個有效的加權遮蔽特性模型，能準確的預測出輸入數位訊號所對應的色彩，因此本研究以加權遮蔽模型為基礎，進一步探討並推導其模式的逆運算模型，提出一個可行正確並簡單的色彩校正模式，將相同的輸入影像訊號透過適當的校正模式能在不同特性的顯示器中呈現出相同的色彩影像。本研究提出近似加權遮蔽模型逆運算的模型，預測出目標色所對應的數位訊號模型，透過數位及影像的各種評估，驗證所提出模型的正確性，同時利用所提的校正模式，將各種不同的螢幕校正到Gamma為2.2的sRGB標準色彩空間，由量測出的Gamma值驗證其精確性。最後，利用各種不同的影像在不同的螢幕上進行色彩校正，也都有不錯的成果。

關鍵字

色彩管理系統；色彩特性； GOG模型；遮蔽模型；底色移除法；色彩校正

並列摘要

With the process of the technology, the LCD has already replaced the CRT and become more popular on the market. However, the same image-signal input always has different color reproductions displayed on different displays and it results in the confusion for the consumer in the e-shopping market. The color calibration of display is necessary to produce the same color productions for the same color image. The color calibration plays the key role in establishing of color management system. For the color calibration, the prediction of digit counts for the desired colors, the accurate color characterization model with available inverse model is required. The weighted masking model using the under color removal technique to take the interaction between channels into account was proposed and the accuracy of the model for predicting color from the input digit count was also indicated. In this research, the inverse characterization model for the weighted masking model is studied to derive an available and accurate color calibration model. In this research, a color calibration model based on the weighted masking model is proposed and the evaluation of the models is also carried out. The experimental results show that the different displays are calibrated into the same color space, such as 2.2 of gamma value, using the proposed model.

並列關鍵字

Color characterization ； Masking model ； color calibration ； Color management system ； Under color removal

參考文獻

[1] CIE, “Commission Internationale de l'Eclairage Proceedings, 1924” Cambridge, Cambridge University Press, 1926-1932.

[3] T. Smith, J. Guild, “The C.I.E. colorimetric standards and their use,” Transactions of the Optical Society, Volume 33, Issue 3, pp. 73-134 (1931).

[4] Gonzalez, Woods, “Digital Image Processing, 2nd ed,” Princeton, 2003.

[8] R. J. W. Brown, D. L. MacAdam, “Visual sensitivities to combined chromaticity and luminance differences,” JOSA, Vol. 39, Issue 10, October, 1949, pp. 808-834.

[9] R. A. Robertson, “Historical development of CIE recommended color difference equations,” Color Research and Application 15, pp. 167-170 (1990).

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基於底色移除法對LCD的色彩校正

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