prepro.py 文件源码

def rotation(x, rg=20, is_random=False, row_index=0, col_index=1, channel_index=2,
                    fill_mode='nearest', cval=0.):
    """Rotate an image randomly or non-randomly.

    Parameters
    -----------
    x : numpy array
        An image with dimension of [row, col, channel] (default).
    rg : int or float
        Degree to rotate, usually 0 ~ 180.
    is_random : boolean, default False
        If True, randomly rotate.
    row_index, col_index, channel_index : int
        Index of row, col and channel, default (0, 1, 2), for theano (1, 2, 0).
    fill_mode : string
        Method to fill missing pixel, default ‘nearest’, more options ‘constant’, ‘reflect’ or ‘wrap’

        - `scipy ndimage affine_transform <https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.ndimage.interpolation.affine_transform.html>`_
    cval : scalar, optional
        Value used for points outside the boundaries of the input if mode='constant'. Default is 0.0

        - `scipy ndimage affine_transform <https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.ndimage.interpolation.affine_transform.html>`_

    Examples
    ---------
    >>> x --> [row, col, 1] greyscale
    >>> x = rotation(x, rg=40, is_random=False)
    >>> tl.visualize.frame(x[:,:,0], second=0.01, saveable=True, name='temp',cmap='gray')
    """
    if is_random:
        theta = np.pi / 180 * np.random.uniform(-rg, rg)
    else:
        theta = np.pi /180 * rg
    rotation_matrix = np.array([[np.cos(theta), -np.sin(theta), 0],
                                [np.sin(theta), np.cos(theta), 0],
                                [0, 0, 1]])

    h, w = x.shape[row_index], x.shape[col_index]
    transform_matrix = transform_matrix_offset_center(rotation_matrix, h, w)
    x = apply_transform(x, transform_matrix, channel_index, fill_mode, cval)
    return x