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本文介绍一种不经坐标转换而达到色度（去相关）拉伸的简单技术，即直接去相关拉伸技术（ＤＤＳ）。在红绿蓝彩色坐标空间，一个颜色矢量可表示为一个彩色分量和一个无色分量。通过减少像元的无色分量，即可对红绿蓝彩色图像进行直接去相关拉伸。首先，检查一下每个彩色像元的红、绿、蓝数码（ＤＮｓ），选定最小值（可是红、绿、蓝三种颜色中的任一个）。在每一个像元的红绿蓝ＤＮ值中减去所选定的最小值，减法运算的结果是一幅减少了无色分量的图像，这也就意味着增加了饱和度。ＤＤＳ方法不使用坐标变换，而由各个波段内的简单计算组成。数学分析和图像实验显示：ＤＤＳ的去相关拉伸在原理上ＩＨＳ转换是相似的，ＤＤＳ在去相关拉伸时更简单、更有效。
This article presents a simple technique to achieve chromatic (decorrelation) stretching without coordinate transformation, ie direct de-correlated stretching (DDS). In the red, green and blue color coordinate space, a color vector can be expressed as a color component and a colorless component. Reduce the color components of the pixel, you can red, green and blue color image directly related to the relevant stretch. First, check the red, green, and blue numbers (DNs) of each color cell for the selected minimum (any of the three colors red, green and blue). Subtracting the selected minimum value from the red, green and blue DN values of each pixel yields a subtraction of the colorless component, which means increased saturation. The DDS method does not use coordinate transformation but consists of simple calculations in each band. Mathematical analysis and image experiments show that the de-correlated stretching of DDS is similar in principle to IHS conversion, and DDS is simpler and more efficient in de-correlated stretching.