from numpy import uint8
def rgbToGray(img):
# 得到(r,g,b)三通道
b = img[:, :, 0].copy()
g = img[:, :, 1].copy()
r = img[:, :, 2].copy()
# 灰度化
out = 0.2126 * r + 0.7152 * g + 0.0722 * b
out = out.astype(uint8)
return out
