It has been suggested that thresholds for discriminating colorimetric purity are systematically higher than those for discriminating hue angle, a difference captured in Judd's phrase "the super-importance of hue." However, to compare the two types of discrimination, the measured thresholds must be expressed in the same units. An attractive test is offered by measurements along the horizontal lines in the chromaticity diagram of MacLeod and Boynton [ J. Opt. Soc. Am.69, 1183 (1979)JOSAAH0030-394110.1364/JOSA.69.001183], i.e., a chromaticity diagram. A horizontal line that extends radially from the white point represents a variation in colorimetric purity alone (and subjectively a variation that is primarily in saturation). In contrast, a horizontal line that runs along the $x$x axis of the diagram, close to the long-wave spectrum locus, corresponds predominantly to variation in hue angle. Yet, in both cases, only the ratio of the excitations of the long- and middle-wave cones is being modulated, and so the thresholds can be expressed in a common metric. Measuring forced-choice thresholds for 180 ms foveal targets presented on a steady field metameric to Illuminant D65, we do not find general support for Judd's working rule that thresholds for purity are systematically twice those for saturation. Thresholds for colorimetric purity were only a little higher than those for hue angle, and the advantage for hue was seen in only part of the ranges that were tested. However, in the upper-left quadrant of the MacLeod-Boynton diagram, where the excitation of short-wave cones is high and where both hue angle and colorimetric purity vary along any given horizontal line, thresholds were indeed sometimes half those observed for discrimination of purity alone.

中文翻译：

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色相角的辨别和比色纯度的辨别用通用度量进行评估。

已经提出，用于区分比色纯度的阈值在系统上高于用于区分色相角的阈值，这是贾德的短语“色调的超重要性”所捕获的。但是，为了比较两种类型的区分，必须以相同的单位表示所测量的阈值。通过在MacLeod和Boynton色度图中沿水平线进行测量，可以提供一种有吸引力的测试方法[J. Opt。Soc。Am.69，1183（1979），JOSAAH0030-394110.1364 / JOSA.69.001183]，即色度图。从白点径向延伸的水平线仅代表比色纯度的变化（主观上主要是饱和度的变化）。相反，沿图的$ x $ x轴延伸的水平线，接近长波频谱轨迹，主要对应于色相角的变化。然而，在这两种情况下，仅长波和中波锥的激励比被调制，因此阈值可以用通用度量表示。测量在发光体D65稳定的同位异构体上出现的180毫秒中央凹目标的强制选择阈值时，我们没有发现普遍支持Judd的工作规则，即纯度阈值系统地是饱和阈值的两倍。比色纯度的阈值仅比色相角的阈值高一点，并且色相的优势仅在部分测试范围内可见。但是，在MacLeod-Boynton图的左上象限中，