说明：  图像融合评价指标，包括有：均值，标准差，信息熵，平均梯度，相关系数，扭曲程度，偏差指数。每个指标都分别对RGB三个波段进行评价。
(This file refers to the ution factor of image fusion,which including:mean,standard deviation,information entropy,average gradient,correlation cofficient,distortion and bias index.Each factor is used to ute every band of RGB of fusion results. )