NASA Langley Res. Center, Hampton, VA.
IEEE Trans Image Process. 1997;6(7):965-76. doi: 10.1109/83.597272.
Direct observation and recorded color images of the same scenes are often strikingly different because human visual perception computes the conscious representation with vivid color and detail in shadows, and with resistance to spectral shifts in the scene illuminant. A computation for color images that approaches fidelity to scene observation must combine dynamic range compression, color consistency-a computational analog for human vision color constancy-and color and lightness tonal rendition. In this paper, we extend a previously designed single-scale center/surround retinex to a multiscale version that achieves simultaneous dynamic range compression/color consistency/lightness rendition. This extension fails to produce good color rendition for a class of images that contain violations of the gray-world assumption implicit to the theoretical foundation of the retinex. Therefore, we define a method of color restoration that corrects for this deficiency at the cost of a modest dilution in color consistency. Extensive testing of the multiscale retinex with color restoration on several test scenes and over a hundred images did not reveal any pathological behaviour.
直接观察和记录的同一场景的彩色图像通常差异很大，因为人类视觉感知以生动的色彩和阴影细节来计算有意识的表现，并且对场景光源的光谱偏移具有抵抗力。要使彩色图像的计算接近对场景观察的保真度，就必须结合动态范围压缩、颜色一致性（一种用于人类视觉颜色恒常性的计算模拟）以及颜色和亮度色调渲染。在本文中，我们将之前设计的单尺度中心/环绕反射率扩展到多尺度版本，从而实现同时进行动态范围压缩/颜色一致性/亮度渲染。这种扩展对于一类图像无法产生良好的颜色渲染效果，因为这些图像违反了反射率理论基础中隐含的灰度世界假设。因此，我们定义了一种颜色恢复方法，可以纠正这种缺陷，但代价是颜色一致性略有降低。在几个测试场景和一百多张图像上对带颜色恢复的多尺度反射率进行了广泛的测试，并未发现任何异常行为。
