Pillow/Tests/test_imageops_usm.py

from __future__ import annotations

from typing import Generator

import pytest

from PIL import Image, ImageFile, ImageFilter


@pytest.fixture
def test_images() -> Generator[dict[str, ImageFile.ImageFile], None, None]:
    ims = {
        "im": Image.open("Tests/images/hopper.ppm"),
        "snakes": Image.open("Tests/images/color_snakes.png"),
    }
    try:
        yield ims
    finally:
        for im in ims.values():
            im.close()


def test_filter_api(test_images: dict[str, ImageFile.ImageFile]) -> None:
    im = test_images["im"]

    test_filter = ImageFilter.GaussianBlur(2.0)
    i = im.filter(test_filter)
    assert i.mode == "RGB"
    assert i.size == (128, 128)

    test_filter2 = ImageFilter.UnsharpMask(2.0, 125, 8)
    i = im.filter(test_filter2)
    assert i.mode == "RGB"
    assert i.size == (128, 128)


def test_usm_formats(test_images: dict[str, ImageFile.ImageFile]) -> None:
    im = test_images["im"]

    usm = ImageFilter.UnsharpMask
    with pytest.raises(ValueError):
        im.convert("1").filter(usm)
    im.convert("L").filter(usm)
    with pytest.raises(ValueError):
        im.convert("I").filter(usm)
    with pytest.raises(ValueError):
        im.convert("F").filter(usm)
    im.convert("RGB").filter(usm)
    im.convert("RGBA").filter(usm)
    im.convert("CMYK").filter(usm)
    with pytest.raises(ValueError):
        im.convert("YCbCr").filter(usm)


def test_blur_formats(test_images: dict[str, ImageFile.ImageFile]) -> None:
    im = test_images["im"]

    blur = ImageFilter.GaussianBlur
    with pytest.raises(ValueError):
        im.convert("1").filter(blur)
    with pytest.raises(ValueError):
        im.convert("I").filter(blur)
    with pytest.raises(ValueError):
        im.convert("F").filter(blur)
    im.convert("RGB").filter(blur)
    im.convert("RGBA").filter(blur)
    im.convert("CMYK").filter(blur)
    with pytest.raises(ValueError):
        im.convert("YCbCr").filter(blur)


def test_usm_accuracy(test_images: dict[str, ImageFile.ImageFile]) -> None:
    snakes = test_images["snakes"]

    src = snakes.convert("RGB")
    i = src.filter(ImageFilter.UnsharpMask(5, 1024, 0))
    # Image should not be changed because it have only 0 and 255 levels.
    assert i.tobytes() == src.tobytes()


def test_blur_accuracy(test_images: dict[str, ImageFile.ImageFile]) -> None:
    snakes = test_images["snakes"]

    i = snakes.filter(ImageFilter.GaussianBlur(0.4))
    # These pixels surrounded with pixels with 255 intensity.
    # They must be very close to 255.
    for x, y, c in [
        (1, 0, 1),
        (2, 0, 1),
        (7, 8, 1),
        (8, 8, 1),
        (2, 9, 1),
        (7, 3, 0),
        (8, 3, 0),
        (5, 8, 0),
        (5, 9, 0),
        (1, 3, 0),
        (4, 3, 2),
        (4, 2, 2),
    ]:
        assert i.im.getpixel((x, y))[c] >= 250
    # Fuzzy match.

    def gp(x: int, y: int) -> tuple[int, ...]:
        return i.im.getpixel((x, y))

    assert 236 <= gp(7, 4)[0] <= 239
    assert 236 <= gp(7, 5)[2] <= 239
    assert 236 <= gp(7, 6)[2] <= 239
    assert 236 <= gp(7, 7)[1] <= 239
    assert 236 <= gp(8, 4)[0] <= 239
    assert 236 <= gp(8, 5)[2] <= 239
    assert 236 <= gp(8, 6)[2] <= 239
    assert 236 <= gp(8, 7)[1] <= 239