White-point preserving color correction
White-point preserving color correction
复制标题
白点保留色彩校正
DOI：
10.2352/cic.1997.5.1.art00051
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发表时间：
1997
影响因子：
1.4
通讯作者：
M. S. Drew
中科院分区：
文献类型：
--
作者：
G. Finlayson;M. S. Drew
为了以设备无关的方式表征由彩色设备（例如扫描仪、彩色复印机和彩色相机）测量的颜色值，必须将这些值转换为色度三刺激值。通常假设RGB与XYZ近似线性相关，因此该转换由最小二乘（LS）线性回归确定。虽然LS方法保证最小化残差平方误差，但它没有关于哪些颜色将被良好映射以及哪些颜色将被不良映射的先验声明。然而，我们认为必须作出这样的声明。特别是因为它是重要的，以保持白色和灰度的颜色复制，我们认为，无色的颜色应保留在颜色校正。这个论点使我们开发了一个新的回归过程：白点保持最小二乘拟合（WPPLS）。顾名思义，该方法找到将RGB映射到XYZ的线性变换，使得在保留白色和格雷的约束下，残差平方误差被最小化。当然，根据定义，WPPLS回归必须在平方误差方面提供比LS过程更差的颜色校正;但是，平方误差不一定与感知的视觉误差相关。事实上，我们提出了一些模拟实验表明，WPPLS程序执行以及或优于LS回归。这些结果为白色在视觉感知和颜色再现中的特权地位提供了实验证实。
To characterize color values measured by color devices (e.g. scanners, color copiers and color cameras) in a device‐ independent fashion these values must be transformed to colorimetric tristimulus values. Often it is assumed that RGBs are approximately linearly related to XYZs and so this transformation is determined by least‐squares (LS) linear regression. While the LS method is guaranteed to minimize the residual squared error it makes no ap riori statement about which colors will be mapped well and which will be mapped poorly. However, we argue that such a statement must be made. In particular because it is important to preserve the white and the gray-scale in color reproduction, we argue that achromatic colors should be preserved in color correction. This argument led us to develop a new regression procedure: the white-point preserving least-squares fit (WPPLS). As the name might suggest, this method finds the linear transform which maps RGBs to XYZs such that the residual squared error is minimized subject to the constraint that white and grays are preserved. Of course, by definition, the WPPLS regression must, in terms of squared error, deliver poorer color correction compared with the LS procedure; but, squared error need not necessarily correlate with perceived visual error. Indeed, we present a number of simulation experiments which show that the WPPLS procedure performs as well or better than the LS regression. These results provide experimental confirmation of the privileged status of white in visual perception and color reproduction.