The color of ocean and sky, blue is perceived as a constant in our lives.
作为海洋和天空的颜色，蓝色被认为是我们生命中的永恒色彩。
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When the hue difference increased, the magnitude of color shift in test target decreased, but the deflection Angle of color shift vector from constant hue line increased.
In this paper, we analyze the variation of saturation, also we compare the previous methods of color constancy and point out that they can not get the constant saturation information.