def steps(image_shape, filter_shape, step_shape):
    """
    Generates feature map coordinates that filters visit

    Parameters
    ----------
    image_shape: tuple of ints
        Image height / width
    filter_shape: tuple of ints
        Filter height / width
    step_shape: tuple of ints
        Step height / width

    Returns
    -------
    ys: Map coordinates along y axis
    xs: Map coordinates along x axis
    """
    h, w = image_shape
    fh, fw = filter_shape
    sh, sw = step_shape

    ys = range(0, h-fh+1, sh)
    xs = range(0, w-fw+1, sw)
    return ys, xs