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update tests and docs

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This commit is contained in:
drhead 2025-04-04 16:11:20 -04:00
parent 9f805f9e69
commit 81c115825b
6 changed files with 74 additions and 4 deletions
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14
Tests/test_image_resample.py
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@ -309,6 +309,8 @@ class TestCoreResampleAlphaCorrect:
self.run_levels_case(case.resize((512, 32), Image.Resampling.HAMMING))
self.run_levels_case(case.resize((512, 32), Image.Resampling.BICUBIC))
self.run_levels_case(case.resize((512, 32), Image.Resampling.LANCZOS))
self.run_levels_case(case.resize((512, 32), Image.Resampling.MKS2013))
self.run_levels_case(case.resize((512, 32), Image.Resampling.MKS2021))
@pytest.mark.xfail(reason="Current implementation isn't precise enough")
def test_levels_la(self) -> None:
@ -318,6 +320,8 @@ class TestCoreResampleAlphaCorrect:
self.run_levels_case(case.resize((512, 32), Image.Resampling.HAMMING))
self.run_levels_case(case.resize((512, 32), Image.Resampling.BICUBIC))
self.run_levels_case(case.resize((512, 32), Image.Resampling.LANCZOS))
self.run_levels_case(case.resize((512, 32), Image.Resampling.MKS2013))
self.run_levels_case(case.resize((512, 32), Image.Resampling.MKS2021))
def make_dirty_case(
self, mode: str, clean_pixel: tuple[int, ...], dirty_pixel: tuple[int, ...]
@ -360,6 +364,12 @@ class TestCoreResampleAlphaCorrect:
self.run_dirty_case(
case.resize((20, 20), Image.Resampling.LANCZOS), (255, 255, 0)
)
self.run_dirty_case(
case.resize((20, 20), Image.Resampling.MKS2013), (255, 255, 0)
)
self.run_dirty_case(
case.resize((20, 20), Image.Resampling.MKS2021), (255, 255, 0)
)
def test_dirty_pixels_la(self) -> None:
case = self.make_dirty_case("LA", (255, 128), (0, 0))
@ -368,6 +378,8 @@ class TestCoreResampleAlphaCorrect:
self.run_dirty_case(case.resize((20, 20), Image.Resampling.HAMMING), (255,))
self.run_dirty_case(case.resize((20, 20), Image.Resampling.BICUBIC), (255,))
self.run_dirty_case(case.resize((20, 20), Image.Resampling.LANCZOS), (255,))
self.run_dirty_case(case.resize((20, 20), Image.Resampling.MKS2013), (255,))
self.run_dirty_case(case.resize((20, 20), Image.Resampling.MKS2021), (255,))
class TestCoreResamplePasses:
@ -453,6 +465,8 @@ class TestCoreResampleBox:
Image.Resampling.HAMMING,
Image.Resampling.BICUBIC,
Image.Resampling.LANCZOS,
Image.Resampling.MKS2013,
Image.Resampling.MKS2021,
),
)
def test_wrong_arguments(self, resample: Image.Resampling) -> None:

8
Tests/test_image_resize.py
View File

@ -72,6 +72,8 @@ class TestImagingCoreResize:
Image.Resampling.HAMMING,
Image.Resampling.BICUBIC,
Image.Resampling.LANCZOS,
Image.Resampling.MKS2013,
Image.Resampling.MKS2021,
),
)
def test_reduce_filters(self, resample: Image.Resampling) -> None:
@ -88,6 +90,8 @@ class TestImagingCoreResize:
Image.Resampling.HAMMING,
Image.Resampling.BICUBIC,
Image.Resampling.LANCZOS,
Image.Resampling.MKS2013,
Image.Resampling.MKS2021,
),
)
def test_enlarge_filters(self, resample: Image.Resampling) -> None:
@ -104,6 +108,8 @@ class TestImagingCoreResize:
Image.Resampling.HAMMING,
Image.Resampling.BICUBIC,
Image.Resampling.LANCZOS,
Image.Resampling.MKS2013,
Image.Resampling.MKS2021,
),
)
@pytest.mark.parametrize(
@ -154,6 +160,8 @@ class TestImagingCoreResize:
Image.Resampling.HAMMING,
Image.Resampling.BICUBIC,
Image.Resampling.LANCZOS,
Image.Resampling.MKS2013,
Image.Resampling.MKS2021,
),
)
def test_enlarge_zero(self, resample: Image.Resampling) -> None:

21
docs/handbook/concepts.rst
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@ -195,6 +195,23 @@ pixel, the Python Imaging Library provides different resampling *filters*.
.. versionadded:: 1.1.3
.. data:: Resampling.MKS2013
:noindex:
Calculate the output pixel value using the Magic Kernel Sharp 2013 filter
(a quadratic B-spline composed with a sharpening kernel) on all pixels that
may contribute to the output value. This filter can only be used with the
:py:meth:`~PIL.Image.Image.resize` and :py:meth:`~PIL.Image.Image.thumbnail`
methods.
.. data:: Resampling.MKS2021
:noindex:
Calculate the output pixel value using the Magic Kernel Sharp 2021 filter
(a quadratic B-spline composed with a sharpening kernel) on all pixels that
may contribute to the output value. This filter can only be used with the
:py:meth:`~PIL.Image.Image.resize` and :py:meth:`~PIL.Image.Image.thumbnail`
methods.
Filters comparison table
~~~~~~~~~~~~~~~~~~~~~~~~
@ -215,3 +232,7 @@ Filters comparison table
+---------------------------+-------------+-----------+-------------+
|:data:`Resampling.LANCZOS` | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐ |
+---------------------------+-------------+-----------+-------------+
|:data:`Resampling.MKS2013` | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐ |
+---------------------------+-------------+-----------+-------------+
|:data:`Resampling.MKS2021` | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐ |
+---------------------------+-------------+-----------+-------------+

14
src/PIL/Image.py
View File

@ -169,7 +169,8 @@ class Resampling(IntEnum):
HAMMING = 5
BICUBIC = 3
LANCZOS = 1
MKS2021 = 6
MKS2013 = 6
MKS2021 = 7
_filters_support = {
@ -178,6 +179,7 @@ _filters_support = {
Resampling.HAMMING: 1.0,
Resampling.BICUBIC: 2.0,
Resampling.LANCZOS: 3.0,
Resampling.MKS2013: 2.5,
Resampling.MKS2021: 4.5,
}
@ -2209,7 +2211,8 @@ class Image:
:param resample: An optional resampling filter. This can be
one of :py:data:`Resampling.NEAREST`, :py:data:`Resampling.BOX`,
:py:data:`Resampling.BILINEAR`, :py:data:`Resampling.HAMMING`,
:py:data:`Resampling.BICUBIC` or :py:data:`Resampling.LANCZOS`.
:py:data:`Resampling.BICUBIC`, :py:data:`Resampling.LANCZOS`,
:py:data:`Resampling.MKS2013`, or :py:data:`Resampling.MKS2021`.
If the image has mode "1" or "P", it is always set to
:py:data:`Resampling.NEAREST`. If the image mode is "BGR;15",
"BGR;16" or "BGR;24", then the default filter is
@ -2244,6 +2247,7 @@ class Image:
Resampling.LANCZOS,
Resampling.BOX,
Resampling.HAMMING,
Resampling.MKS2013,
Resampling.MKS2021,
):
msg = f"Unknown resampling filter ({resample})."
@ -2257,6 +2261,7 @@ class Image:
(Resampling.BICUBIC, "Image.Resampling.BICUBIC"),
(Resampling.BOX, "Image.Resampling.BOX"),
(Resampling.HAMMING, "Image.Resampling.HAMMING"),
(Resampling.MKS2013, "Image.Resampling.MKS2013"),
(Resampling.MKS2021, "Image.Resampling.MKS2021"),
)
]
@ -2694,7 +2699,8 @@ class Image:
:param resample: Optional resampling filter. This can be one
of :py:data:`Resampling.NEAREST`, :py:data:`Resampling.BOX`,
:py:data:`Resampling.BILINEAR`, :py:data:`Resampling.HAMMING`,
:py:data:`Resampling.BICUBIC` or :py:data:`Resampling.LANCZOS`.
:py:data:`Resampling.BICUBIC`, :py:data:`Resampling.LANCZOS`,
:py:data:`Resampling.MKS2013`, or :py:data:`Resampling.MKS2021`.
If omitted, it defaults to :py:data:`Resampling.BICUBIC`.
(was :py:data:`Resampling.NEAREST` prior to version 2.5.0).
See: :ref:`concept-filters`.
@ -2912,12 +2918,14 @@ class Image:
Resampling.BOX,
Resampling.HAMMING,
Resampling.LANCZOS,
Resampling.MKS2013,
Resampling.MKS2021,
):
unusable: dict[int, str] = {
Resampling.BOX: "Image.Resampling.BOX",
Resampling.HAMMING: "Image.Resampling.HAMMING",
Resampling.LANCZOS: "Image.Resampling.LANCZOS",
Resampling.MKS2013: "Image.Resampling.MKS2013",
Resampling.MKS2021: "Image.Resampling.MKS2021",
}
msg = unusable[resample] + f" ({resample}) cannot be used."

3
src/libImaging/Imaging.h
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@ -269,7 +269,8 @@ ImagingError_Clear(void);
#define IMAGING_TRANSFORM_HAMMING 5
#define IMAGING_TRANSFORM_BICUBIC 3
#define IMAGING_TRANSFORM_LANCZOS 1
#define IMAGING_TRANSFORM_MKS2021 6
#define IMAGING_TRANSFORM_MKS2013 6
#define IMAGING_TRANSFORM_MKS2021 7
typedef int (*ImagingTransformMap)(double *X, double *Y, int x, int y, void *data);
typedef int (*ImagingTransformFilter)(void *out, Imaging im, double x, double y);

18
src/libImaging/Resample.c
View File

@ -79,6 +79,20 @@ lanczos_filter(double x) {
return 0.0;
}
static inline double
mks_2013_filter(double x) {
/* https://johncostella.com/magic/ */
if (x < 0.0)
x = -x;
if (x < 0.5)
return 17.0 / 16.0 - 7.0 / 4.0 * pow(x, 2.0);
if (x < 1.5)
return (1.0 - x) * (7.0/4.0 - x);
if (x < 2.5)
return -1.0 / 8.0 * pow(x - 5.0 / 2.0, 2.0);
return (0.0);
}
static inline double
mks_2021_filter(double x) {
/* https://johncostella.com/magic/ */
@ -102,6 +116,7 @@ static struct filter BILINEAR = {bilinear_filter, 1.0};
static struct filter HAMMING = {hamming_filter, 1.0};
static struct filter BICUBIC = {bicubic_filter, 2.0};
static struct filter LANCZOS = {lanczos_filter, 3.0};
static struct filter MKS2013 = {mks_2013_filter, 2.5};
static struct filter MKS2021 = {mks_2021_filter, 4.5};
/* 8 bits for result. Filter can have negative areas.
@ -712,6 +727,9 @@ ImagingResample(Imaging imIn, int xsize, int ysize, int filter, float box[4]) {
case IMAGING_TRANSFORM_LANCZOS:
filterp = &LANCZOS;
break;
case IMAGING_TRANSFORM_MKS2013:
filterp = &MKS2013;
break;
case IMAGING_TRANSFORM_MKS2021:
filterp = &MKS2021;
break;