Figure S5. Luminance plots

Boxplots of luminance measurements obtained from plumage patches with <0.05 luminance reflectance: (a) mantle, (b) throat, and (c) black of head. Hue measurements were excluded from these patches because very dark colors yield random hues when converted into opponent colorspace. Each box is bounded by the first and third quartiles, and plot whiskers extend to 1.5 times the interquartile range or to the maximum and minimum value, as appropriate. Data points outside the whisker range are represented by open circles.

针对亮度反射率低于0.05的羽毛色块所开展的亮度测量箱线图（boxplots）：(a) 背部区域，(b) 喉部区域，以及(c) 头部黑色羽区。由于颜色极深的色块在转换至对立色空间（opponent colorspace）时会产生随机色相值，因此此类色块的色相测量数据已被排除。每个箱体的上下边界分别对应第一四分位数与第三四分位数，箱须延伸至1.5倍四分位距（interquartile range）范围，或视实际情况延伸至数据的最大值与最小值。超出箱须范围的数据点以空心圆圈标示。