image_utils.py 文件源码

def normalise_images(X):
    '''
    Helper for making the images zero mean and unit standard deviation i.e. `white`
    '''

    X_white = np.zeros(X.shape, dtype=np.float32)

    for ii in range(X.shape[0]):

        Xc = X[ii,:,:,:]
        mc = Xc.mean()
        sc = Xc.std()

        Xc_white = np.divide((Xc - mc), sc)

        X_white[ii,:,:,:] = Xc_white

    return X_white.astype(np.float32)