Pillow

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from __future__ import annotations
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import pytest
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from PIL import Image, ImageEnhance
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from .helper import assert_image_equal, hopper
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def test_sanity() -> None:
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    # FIXME: assert_image
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    # Implicit asserts no exception:
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    ImageEnhance.Color(hopper()).enhance(0.5)
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    ImageEnhance.Contrast(hopper()).enhance(0.5)
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    ImageEnhance.Brightness(hopper()).enhance(0.5)
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    ImageEnhance.Sharpness(hopper()).enhance(0.5)
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def test_crash() -> None:
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    # crashes on small images
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    im = Image.new("RGB", (1, 1))
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    ImageEnhance.Sharpness(im).enhance(0.5)
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def _half_transparent_image() -> Image.Image:
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    # returns an image, half transparent, half solid
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    im = hopper("RGB")
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    transparent = Image.new("L", im.size, 0)
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    solid = Image.new("L", (im.size[0] // 2, im.size[1]), 255)
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    transparent.paste(solid, (0, 0))
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    im.putalpha(transparent)
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    return im
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def _check_alpha(
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    im: Image.Image, original: Image.Image, op: str, amount: float
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) -> None:
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    assert im.getbands() == original.getbands()
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    assert_image_equal(
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        im.getchannel("A"),
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        original.getchannel("A"),
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        f"Diff on {op}: {amount}",
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    )
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@pytest.mark.parametrize("op", ("Color", "Brightness", "Contrast", "Sharpness"))
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def test_alpha(op: str) -> None:
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    # Issue https://github.com/python-pillow/Pillow/issues/899
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    # Is alpha preserved through image enhancement?
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    original = _half_transparent_image()
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    for amount in [0, 0.5, 1.0]:
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        _check_alpha(
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            getattr(ImageEnhance, op)(original).enhance(amount),
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            original,
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            op,
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            amount,
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        )
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