為了探索展示物之照明的最佳演色光源議題,藉以了解不同光源對於展示物演色性的影響,本研究針對獨立色中少有相關研究的金色,選定精品展示中的黃金加工品,探討其顯現外觀色彩之程度。其方法為比較樣本光源,包括鎢絲燈、螢光燈、LED燈及RGB LED元件,分別照射黃金樣品,以獲得其不同之色度座標,供「色差」(color difference)之比較。 本研究利用CIE LAB均勻色彩空間之色差公式,來評價各種光源照射黃金之色彩差異。研究結果顯示(1)對黃金最佳演色之單一光源為DURO-TEST (Color Classer 75)螢光燈,(2)最差之光源為GE冷白螢光燈,(3)混合光源對黃金最佳之演色光源為DURO-TEST (Color Classer 75)螢光燈與OSRAM鹵素燈,(4)LED燈對黃金最佳之演色光源為平均演色係數92.5、色溫3187K、主波長580nm的LED崁燈,(5)RGB LED元件組成之光源,可藉由電流的調控來改變三原色光譜,找到對黃金有較小色差值之最佳演色光源。 對特定展示物而言,利用平均演色指數判斷燈具之演色效果並不可靠,未來在展示物照明之設計應用上,可利用CIE Lab色差值的計算方式,為博物館或特定展示物品,找到最佳的展示物演色光源。 關鍵字:展示照明,演色性,色差,LED,黃金加工品
In order to explore the best color rendering performance of light sources, this study conducted a series of experiments to obtain comparative advantages of sample light sources on the target on display: a thin sheet of gold plate. To to do, light sources, including daylight, incandescent, LED lamps, and fluorescent light tubes were set on the top of the gole plate and cast light beams in a 45 degree angle for the Coloriphotometer (PR650). The purpose was to obtain CIE1931 chromaticity coordinates and relevant parameters to proceed to color difference comparisons. In this study, color-difference formula derived from CIELab uniform color space was adopted to evaluate gold color differences under all kinds of light sources. It is found the light beam mixed with fluorescent lamp DURO-TEST (Color Classer 75) and OSRAM halogen had the best color performance on the gold sample; the worst, on the other hand, was GE cool white fluorescent tube. In addition, three individual light sources are identified regarding color performance, they include DURO-TEST (Color Classer 75)fluorescent tube, the LED test lamp with the capacity of 92.5 CRI, 3187K color temperature, and the dimmable RGB LED chips. Based on the experimental result, it can be coluluded that color rendering index alone was not necessarily reliable to locate suitable light source. It is highly recommended, however, the color difference formula of CIE Lab be the way to successfully carry out the task. Keywords: Display lighting,Color rendering property,Color difference,LED,Gold processed