Color Gamut of White Light Sources

白光色域

A color gamut is generally defined as a two dimensional area, like that represented in xy or u’v’ color space. Color gamut is commonly used in the display and printing industries to define the amount of colors that can be reproduced with those systems. However, with innovative light sources that enable the rendering of more vivid colors, color gamut area is fast becoming a critical metric for evaluating light sources. A color gamut is formed by a specific set of colors rendered by the source and is also referred to as the gamut area. If a different set of colors is used the gamut area will be different.

色域通常定义为二维区域,如xy或者u‘v’色空间。色域通常用于显示和印刷行业,以确定这些系统可以复制的颜色的数量。然而,随着创新的光源,使渲染更生动的颜色,色域面积正在迅速成为一个重要的度量评估光源。色域是由源呈现的一组特定颜色形成的,也称为色域区域。如果使用不同的一套颜色,色域区域将不同。

It’s important to understand that color rendering and color gamut are quite different but connected. Color rendering of a light source is measured by the Color Rendering Index (CRI). This is usually done by comparing the rendering of the first eight CRI reference colors by the test source to a reference source.  The gamut of the colors rendered by the light source can be measured by a metric known as Gamut Area Index (GAI). If the color points used to calculate CRI are connected in a two dimensional space, the bounded area they form is the gamut area.

重要的是要明白,颜色渲染和色域是完全不同的,连接光源的颜色渲染是通过颜色渲染索引(CRI)来测量的。这通常是通过将测试源对前八个CRI参考色的呈现与一个参考源进行比较来完成的。由光源渲染的颜色的色域可以通过称为全色域指数(GAI)的度量来测量。如果用于计算显指的色点连接在一个二维空间中,它们形成的有界区域是色域区域。

Rendering the colors used in CRI with a black body, at a CCT of 3000K, will produce a CRI of 100. This is what light sources, of 3000K CCT, are generally compared to for the determination of CRI. For any light source that doesn’t render the color points exactly as rendered by the black body, CRI will be less than 100. Connecting the rendered color points will form a gamut area as shown in Figure 1. A gamut area can be defined for any light source that has been measured for CRI.

渲染的颜色用一个黑色的机构,在一个3000K的国家,将产生一个100的显指。这是什么光源,3000K的CCT,一般比较为确定的显指。对于任何光源,不渲染的颜色点完全由黑体渲染,国际台将小于100。连接渲染的颜色点将形成一个色域区域,如图1所示。一个色域可以被定义为任何光源,已被测量为显指。

Figure 1. Color Gamut Area of a blackbody radiator with a CRI of 100. The connected points represent color rendering references R1 – R8.

图1.黑体散热器的色域面积为100。连接点代表颜色渲染参考R1–R8。

Gamut Area Index (GAI) is calculated by dividing the gamut area formed by the light source with the gamut area formed by the reference source using the same set of colors that are used for CRI. By definition, any light source with CRI of 100 will have a corresponding GAI. Figure 2 shows the gamut area of HONOURTEK Vigour Series® at 3000K compared to the blackbody radiator gamut area representing a CRI of 100.

全色域指数(GAI)是通过使用与显指相同的一套颜色将光源形成的色域范围与参考源形成的颜色范围除以来计算的。根据定义,任何光源的显指为100将有一个相应的全色域指数。图2显示了HONOURTEK 炫彩系列的色域区域在3000K相比,黑体辐射器的色域面积代表的显指为100。

Note: GAI, as originally published, uses an Equal Energy Spectrum as the reference source rather than the black body. HONOURTEK reports both numbers but believes that using the blackbody reference is more meaningful.

注:全色域指数,正如最初发表的,使用等能谱作为参考源,而不是黑体。HONOURTEK报告这两个数字,但认为使用黑体参考更有意义。

Neither CRI nor GAI on their own are indicators of visual preference. Research has shown that in some cases there is a desire for colors to look more vigorous than is possible with a source that has a CRI of 100. If the reference colors are rendered more vibrantly, then CRI will be less than 100 and they will represent a larger gamut than the reference source, as seen in Figure 2. This increase in gamut area can be measured using the Gamut Area Index. It should be noted that a higher GAI number will not always mean that all colors are more vigorous. A higher GAI number can be achieved by increasing the gamut area only in certain regions of the color space. Therefore, it is important to also look at the gamut area plots, as seen in Figure 2, to get a complete understanding of the regions where there is an increase in gamut area.

无论是显指还是全色域指数本身都不是视觉偏好的标志。研究表明,在某些情况下,人们希望颜色看起来比使用一个100度的显指源更有活力。如果参考色被渲染的更有活力,那么显指将小于100,并且它们将代表比参考源更大的色域,如图2所示。色域面积的增加可以用全色域指数来衡量。需要注意的是,一个更高的全色域指数数字并不总是意味着所有的颜色都更有活力。只有在颜色空间的某些区域增加色域面积,才能获得更高的全色域指数。因此,还必须查看色域图,如图2所示,以全面了解色域面积增加的区域。

Figure 2. The gamut area of the VIGOUR Series® is not exactly the same as the blackbody reference so CRI by definition is less than 100, however the gamut area is larger and therefore has a higher GAI.

图2.炫彩系列的色域面积与黑体参考不完全一样,所以显示的定义是小于100,但是色域面积较大,因此具有较高的色域面积指数。

HONOURTEK’s color scientists engineered the spectral power distribution of the Vigour Series® light so that the colors look more vigorous compared to a halogen lamp for example. Balancing the consideration of CRI and GAI allows the light to achieve the preferred level of vividness without appearing un-natural.

HONOURTEK的色彩科学家设计了活力系列的光谱功率分布。光使颜色看起来更有活力相比卤素灯例如。平衡对显指和色域面积指数的考虑,允许光线达到优选水平的生动性,而不会显得不自然。