代码：https://github.com/inksci/Record-DNN/blob/master/Image%20invert%20coded%20by%20inksci-v2.ipynb

将 x 乘以 1

将 x 乘以 100

print( np.max(reaults["x_var"]), np.min(reaults["x_var"]) )
# (5.6692595, -2.6532571)

将 x 乘以 255

print( np.max(reaults["x_var"]), np.min(reaults["x_var"]) )
# (4.154356, -2.7749074)