How to use the pyvips.Image.xyz function in pyvips

def test_xyz(self):
        im = pyvips.Image.xyz(128, 128)
        assert im.bands == 2
        assert im.format == pyvips.BandFormat.UINT
        assert im.width == 128
        assert im.height == 128
        p = im(45, 35)
        assert_almost_equal_objects(p, [45, 35])

def to_polar(image):
    """Transform image coordinates to polar.

    The image is transformed so that it is wrapped around a point in the
    centre. Vertical straight lines become circles or segments of circles,
    horizontal straight lines become radial spokes.
    """
    # xy image, zero in the centre, scaled to fit image to a circle
    xy = pyvips.Image.xyz(image.width, image.height)
    xy -= [image.width / 2.0, image.height / 2.0]
    scale = min(image.width, image.height) / float(image.width)
    xy *= 2.0 / scale

    # to polar, scale vertical axis to 360 degrees
    index = run_cmplx(lambda x: x.polar(), xy)
    index *= [1, image.height / 360.0]

    return image.mapim(index)

def to_rectangular(image):
    """Transform image coordinates to rectangular.

    The image is transformed so that it is unwrapped from a point in the
    centre. Circles or segments of circles become vertical straight lines,
    radial lines become horizontal lines.
    """
    # xy image, vertical scaled to 360 degrees
    xy = pyvips.Image.xyz(image.width, image.height)
    xy *= [1, 360.0 / image.height]

    # to rect, scale to image rect
    index = run_cmplx(lambda x: x.rect(), xy)
    scale = min(image.width, image.height) / float(image.width)
    index *= scale / 2.0
    index += [image.width / 2.0, image.height / 2.0]

    return image.mapim(index)

def to_polar(image):
    """Transform image coordinates to polar.

    The image is transformed so that it is wrapped around a point in the
    centre. Vertical straight lines become circles or segments of circles,
    horizontal straight lines become radial spokes.
    """
    # xy image, zero in the centre, scaled to fit image to a circle
    xy = pyvips.Image.xyz(image.width, image.height)
    xy -= [image.width / 2.0, image.height / 2.0]
    scale = min(image.width, image.height) / float(image.width)
    xy *= 2.0 / scale

    # to polar, scale vertical axis to 360 degrees
    index = run_cmplx(lambda x: x.polar(), xy)
    index *= [1, image.height / 360.0]

    return image.mapim(index)

def to_polar(image):
    """Transform image coordinates to polar.

    The image is transformed so that it is wrapped around a point in the
    centre. Vertical straight lines become circles or segments of circles,
    horizontal straight lines become radial spokes.
    """
    # xy image, origin in the centre, scaled to fit image to a circle
    xy = pyvips.Image.xyz(image.width, image.height)
    xy -= [image.width / 2.0, image.height / 2.0]
    scale = min(image.width, image.height) / float(image.width)
    xy *= 2.0 / scale

    index = xy.polar()

    # scale vertical axis to 360 degrees
    index *= [1, image.height / 360.0]

    return image.mapim(index)

def to_rectangular(image):
    """Transform image coordinates to rectangular.

    The image is transformed so that it is unwrapped from a point in the
    centre. Circles or segments of circles become vertical straight lines,
    radial lines become horizontal lines.
    """
    # xy image, vertical scaled to 360 degrees
    xy = pyvips.Image.xyz(image.width, image.height)
    xy *= [1, 360.0 / image.height]

    index = xy.rect()

    # scale to image rect
    scale = min(image.width, image.height) / float(image.width)
    index *= scale / 2.0
    index += [image.width / 2.0, image.height / 2.0]

    return image.mapim(index)

def wobble(image):
    # this makes an image where pixel (0, 0) (at the top-left) has value [0, 0],
    # and pixel (image.width, image.height) at the bottom-right has value
    # [image.width, image.height]
    index = pyvips.Image.xyz(image.width, image.height)

    # make a version with (0, 0) at the centre, negative values up and left,
    # positive down and right
    centre = index - [image.width / 2, image.height / 2]

    # to polar space, so each pixel is now distance and angle in degrees
    polar = centre.polar()

    # scale sin(distance) by 1/distance to make a wavey pattern
    d = 10000 * (polar[0] * 3).sin() / (1 + polar[0])

    # and back to rectangular coordinates again to make a set of vectors we can
    # apply to the original index image
    index += d.bandjoin(polar[1]).rect()

    # finally, use our modified index image to distort the input!