函数：
bitwiseAnd(image2)
Calculates the bitwise AND of the input values for each matched pair of bands in image1 and image2. If either image1 or image2 has only 1 band, then it is used against all the bands in the other image. If the images have the same number of bands, but not the same names, they e used pairwise in the natural order. The output bands are named for the longer of the two inputs,
