Pillow/Tests/test_image_transform.py

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from helper import unittest, PillowTestCase, tearDownModule, lena
from PIL import Image
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class TestImageTransform(PillowTestCase):
def test_extent(self):
im = lena('RGB')
(w, h) = im.size
transformed = im.transform(im.size, Image.EXTENT,
(0, 0,
w//2, h//2), # ul -> lr
Image.BILINEAR)
scaled = im.resize((w*2, h*2), Image.BILINEAR).crop((0, 0, w, h))
# undone -- precision?
self.assert_image_similar(transformed, scaled, 10)
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def test_quad(self):
# one simple quad transform, equivalent to scale & crop upper left quad
im = lena('RGB')
(w, h) = im.size
transformed = im.transform(im.size, Image.QUAD,
(0, 0, 0, h//2,
# ul -> ccw around quad:
w//2, h//2, w//2, 0),
Image.BILINEAR)
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scaled = im.resize((w*2, h*2), Image.BILINEAR).crop((0, 0, w, h))
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self.assert_image_equal(transformed, scaled)
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def test_mesh(self):
# this should be a checkerboard of halfsized lenas in ul, lr
im = lena('RGBA')
(w, h) = im.size
transformed = im.transform(im.size, Image.MESH,
[((0, 0, w//2, h//2), # box
(0, 0, 0, h,
w, h, w, 0)), # ul -> ccw around quad
((w//2, h//2, w, h), # box
(0, 0, 0, h,
w, h, w, 0))], # ul -> ccw around quad
Image.BILINEAR)
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# transformed.save('transformed.png')
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scaled = im.resize((w//2, h//2), Image.BILINEAR)
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checker = Image.new('RGBA', im.size)
checker.paste(scaled, (0, 0))
checker.paste(scaled, (w//2, h//2))
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self.assert_image_equal(transformed, checker)
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# now, check to see that the extra area is (0, 0, 0, 0)
blank = Image.new('RGBA', (w//2, h//2), (0, 0, 0, 0))
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self.assert_image_equal(blank, transformed.crop((w//2, 0, w, h//2)))
self.assert_image_equal(blank, transformed.crop((0, h//2, w//2, h)))
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def _test_alpha_premult(self, op):
# create image with half white, half black,
# with the black half transparent.
# do op,
# there should be no darkness in the white section.
im = Image.new('RGBA', (10, 10), (0, 0, 0, 0))
im2 = Image.new('RGBA', (5, 10), (255, 255, 255, 255))
im.paste(im2, (0, 0))
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im = op(im, (40, 10))
im_background = Image.new('RGB', (40, 10), (255, 255, 255))
im_background.paste(im, (0, 0), im)
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hist = im_background.histogram()
self.assertEqual(40*10, hist[-1])
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def test_alpha_premult_resize(self):
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def op(im, sz):
return im.resize(sz, Image.LINEAR)
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self._test_alpha_premult(op)
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def test_alpha_premult_transform(self):
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def op(im, sz):
(w, h) = im.size
return im.transform(sz, Image.EXTENT,
(0, 0,
w, h),
Image.BILINEAR)
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self._test_alpha_premult(op)
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def test_blank_fill(self):
# attempting to hit
# https://github.com/python-pillow/Pillow/issues/254 reported
#
# issue is that transforms with transparent overflow area
# contained junk from previous images, especially on systems with
# constrained memory. So, attempt to fill up memory with a
# pattern, free it, and then run the mesh test again. Using a 1Mp
# image with 4 bands, for 4 megs of data allocated, x 64. OMM (64
# bit 12.04 VM with 512 megs available, this fails with Pillow <
# a0eaf06cc5f62a6fb6de556989ac1014ff3348ea
#
# Running by default, but I'd totally understand not doing it in
# the future
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foo = [Image.new('RGBA', (1024, 1024), (a, a, a, a))
for a in range(1, 65)]
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# Yeah. Watch some JIT optimize this out.
foo = None
self.test_mesh()
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if __name__ == '__main__':
unittest.main()
# End of file