A color space is a three‐dimensional representation of all the possible color percepts. The CIE 1976 L*a*b* is one of the most widely used object color spaces. In CIELAB, lightness L* is limited between 0 and 100, while a* and b* coordinates have no fixed boundaries. The outer boundaries of CIELAB have been previously calculated using theoretical object spectral reflectance functions and the CIE 1931 and 1964 observers under the CIE standard illuminants D50 and D65. However, natural and manufactured objects reflect light smoothly as opposed to theoretical spectral reflectance functions. Here, data generated from a linear optimization method are analyzed to re‐evaluate the outer boundaries of the CIELAB. The color appearance of 99 test color samples under theoretical test spectra has been calculated in the CIELAB using CIE 1931 standard observer. The lightness L* boundary ranged between 6 and 97, redness‐greenness a* boundary ranged between −199 and 270, and yellowness‐blueness b* boundary ranged between −74 and 161. The boundary in the direction of positive b* (yellowness) was close to the previous findings. While the positive a* (redness) boundary exceeded previously known limits, the negative a* (greenness) and b* (blueness) boundaries were lower than the previously calculated CIELAB boundaries. The boundaries found here are dependent on the color samples used here and the spectral shape of the test light sources. Irregular spectral shapes and more saturated color samples can result in extended boundaries at the expense of computational time and power.

中文翻译：

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理论光谱和99种测试颜色样本下的CIELAB颜色空间边界

颜色空间是所有可能的颜色感知的三维表示。CIE 1976 L * a * b *是使用最广泛的对象颜色空间之一。在CIELAB中，亮度L *限制在0到100之间，而a *和b*坐标没有固定边界。CIELAB的外边界先前已使用理论目标光谱反射函数以及CIE标准光源D50和D65下的CIE 1931和1964观察者进行了计算。然而，与理论光谱反射函数相反，天然和人造物体能平滑地反射光。在此，将分析通过线性优化方法生成的数据，以重新评估CIELAB的外部边界。已在CIELAB中使用CIE 1931标准观察器计算了在理论测试光谱下的99种测试颜色样品的颜色外观。亮度L *边界范围在6到97之间，红色-绿色a *边界范围在-199和270之间，黄色-蓝色b*边界范围在-74和161之间。正b *（黄色）方向的边界与先前的发现接近。当a *（红色）正边界超出了先前已知的限制时，a *（绿色）和b *（蓝色）负边界小于先前计算的CIELAB边界。在此找到的边界取决于在此使用的颜色样本和测试光源的光谱形状。不规则的光谱形状和更饱和的颜色样本会导致边界扩展，但会浪费计算时间和功能。