全彩發光二極體與顯示螢幕之間的色彩校正

Abstract

近年來，全彩發光二極體（Multi-color LED）越來越廣泛的被使用在室內景觀設計之領域。然而，LED與顯示螢幕的色彩空間不同，使得室內設計師在經由螢幕軟體所調配出的燈光色彩與真實的LED色彩會有所不同。本系統的目的就是找到LED與顯示螢幕的相對色彩對應關係，讓設計師能經由螢幕的色碼就能調出真正的燈光色彩。相較於以往色彩校正使用較昂貴的色度計來進行校正，我們提出的演算法能經由隨手可得的數位相機達到螢幕與LED色彩一致的效果。本研究提出之色彩校正演算法分為兩個部分，第一部分為對相機及螢幕進行gamma校正讓螢幕與LED的輸入與輸出為線性變化，第二部分是計算出LED與顯示螢幕的色彩對應關係。最後我們就可以用這個對應關係，用螢幕來選擇我們想要的燈光色彩了。據我們所知，本篇論文所提出的方法是第一個使用低成本數位相機自動校正LED與螢幕之間的色彩的系統，並在情緒燈光之應用上有相當大的潛力。

Monitor-based LED light casting has a large color variation. As designers design a lighting space, they cannot employ monitor color palette to choose the LED color due to color definition varies between monitors and multi-color LEDs. To address this problem, we use a low cost camera as measurement device to achieve color consistency of monitor based light casting. Our method contains three calibration steps: Firstly, we perform a gamma correction in the monitor and the LEDs. Secondary, the color matching between the monitor and the LEDs is found automatically. Finally, the linear transformation function of the LEDs and the monitor color space is constructed by using a linear operation. Experimental results show the proposed calibration algorithm successfully make the color variation becomes slighter. Moreover, we evaluate the calibration result with a chroma meter, which shows the color differences of three primary colors between the monitor and the LED become much lesser. To the best of our knowledge, this is the first effort to achieve color consistency between the monitor and the LEDs by using a commodity off-the-shelf product like an inexpensive digital camera. Our method has a great potential for many applications that requires the multi-color LED light such as emotional light system.