bayer.py 文件源码

def I(n, transposed=False):
    """Get the index matrix with side of length ``n``.

    Will only work if ``n`` is a power of 2.

    Reference: http://caca.zoy.org/study/part2.html

    :param int n: Power of 2 side length of matrix.
    :param bool transposed:
    :return: The index matrix.

    """
    if n == 2:
        if transposed:
            return np.array([[0, 3], [2, 1]], 'int')
        else:
            return np.array([[0, 2], [3, 1]], 'int')
    else:
        smaller_I = I(n >> 1, transposed)
        if transposed:
            return np.bmat([[4 * smaller_I, 4 * smaller_I + 3],
                            [4 * smaller_I + 2, 4 * smaller_I + 1]])
        else:
            return np.bmat([[4 * smaller_I,     4 * smaller_I + 2],
                            [4 * smaller_I + 3, 4 * smaller_I + 1]])