以多色LED為探測光源的反射式色度儀之精度改善演算法

Accuracy-improvement algorithm for a reflective colorimeter using multicolor LEDs as probing light sources

楊寶賡(Pao-Keng Yang)

《光學工程》 127期 (2014/11) Pp. 13-17

摘要

我們建構一套以發光二極體（LED）為探測光源的色彩量測系統。系統量測不同波長LED照射待測物體表面的反射率值，進而估算待測物體表面的反射率光譜，可得到物體在標準光源照射下會呈現的顏色。然而，在LED數目有限與LED光譜有限分布（非單色光）效應的影響下，所量到的反射率並不足以忠實反應整個反射率光譜，所算出的色度座標會與正確座標值產生誤差。我們開發一有效的校正演算法，由有限數據重建整個反射率光譜並去除LED光譜有限分布所造成的光譜擴散效應，來拉近我們所量測的結果與標準儀器所量到的值。

關鍵字

反射式色度計 ； 發光二極體 ； 反射率光譜

並列摘要

We built a reflective color-measuring setup using multicolor LEDs as probing light sources. The color of the test surface as illuminated by a light source with a given power spectrum can be calculated as long as the spectral reflectance of the surface has been fully characterized. In our setup, the spectral reflectance was determined by measuring the reflectivity values as illuminated by LEDs in different colors, respectively. On account of the limited number of LEDs and spectral broadening effect resulting from the finite bandwidth of LED, the measured spectral reflectance will deviate from the real one to some extent. We developed an effective calibrating procedure to reliably reconstruct the spectral reflectance from discrete reflectance values. The resulting spectral reflectance was found to be free from the spectral-broadening effect due to the finite bandwidth of LED and will give a more accurate prediction in the color coordinate value.

並列關鍵字

reflective colorimeter ； LED ； spectral reflectance