针对彩色编码投影光栅三维轮廓术所需的分色技术要求,根据光度学的原理,提出了一种由RGB格式到HIS格式的变换关系,同时给出了逆变换关系式。亮度I定义为R、G、B三个分量的平均值。白度S定义为R,G,B三个分量中最小的分量除以亮度值。用R,G,B三个分量中的最小值去减另外两个分量,得到该像素所对应的光谱色,然后由这两个分量的比值来确定色度H。在HIS格式中将亮度与颜色信息分离开,在进行分色处理时可以不受亮度变化的影响。通过设定固定的阈值,可以将红、绿、蓝、青、品、黄几种颜色有效地区分开来。

A transformation from RGB model to HIS model is prosented based on the luminosity of the object and its reverse transformation. I is used to represent the brightness of the color defined as the average value of RGB, and S is used to represent the whiteness of the color defined as the minimum value of RGB divided by brightness. H is used to represent the hue of the color. Two larger values of RGB are subtracted by the minimum value of RGB. The H is defined as the ratio of the differences. In HIS model, the brightness is separated from color. Thus, the brightness has no influence on the distinction of colors. By setting certain thresholds, it is easy to distinguish red, green, cyan, magenta and yellow strips in HIS model.