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Merge pull request #4320 from uploadcare/rgb2l-rounding-error

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Fix rounding error on RGB to L conversion
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Andrew Murray 2020-01-01 20:09:34 +11:00 committed by GitHub
commit 4203845a24
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9 changed files with 21 additions and 18 deletions
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Tests/images/imagedraw_floodfill_L.png
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6
Tests/test_image_entropy.py
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@ -7,9 +7,9 @@ class TestImageEntropy(PillowTestCase):
return hopper(mode).entropy()
self.assertAlmostEqual(entropy("1"), 0.9138803254693582)
self.assertAlmostEqual(entropy("L"), 7.06650513081286)
self.assertAlmostEqual(entropy("I"), 7.06650513081286)
self.assertAlmostEqual(entropy("F"), 7.06650513081286)
self.assertAlmostEqual(entropy("L"), 7.063008716585465)
self.assertAlmostEqual(entropy("I"), 7.063008716585465)
self.assertAlmostEqual(entropy("F"), 7.063008716585465)
self.assertAlmostEqual(entropy("P"), 5.0530452472519745)
self.assertAlmostEqual(entropy("RGB"), 8.821286587714319)
self.assertAlmostEqual(entropy("RGBA"), 7.42724306524488)

6
Tests/test_image_getdata.py
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@ -20,9 +20,9 @@ class TestImageGetData(PillowTestCase):
return data[0], len(data), len(list(data))
self.assertEqual(getdata("1"), (0, 960, 960))
self.assertEqual(getdata("L"), (16, 960, 960))
self.assertEqual(getdata("I"), (16, 960, 960))
self.assertEqual(getdata("F"), (16.0, 960, 960))
self.assertEqual(getdata("L"), (17, 960, 960))
self.assertEqual(getdata("I"), (17, 960, 960))
self.assertEqual(getdata("F"), (17.0, 960, 960))
self.assertEqual(getdata("RGB"), ((11, 13, 52), 960, 960))
self.assertEqual(getdata("RGBA"), ((11, 13, 52, 255), 960, 960))
self.assertEqual(getdata("CMYK"), ((244, 242, 203, 0), 960, 960))

8
Tests/test_image_getextrema.py
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@ -9,14 +9,14 @@ class TestImageGetExtrema(PillowTestCase):
return hopper(mode).getextrema()
self.assertEqual(extrema("1"), (0, 255))
self.assertEqual(extrema("L"), (0, 255))
self.assertEqual(extrema("I"), (0, 255))
self.assertEqual(extrema("F"), (0, 255))
self.assertEqual(extrema("L"), (1, 255))
self.assertEqual(extrema("I"), (1, 255))
self.assertEqual(extrema("F"), (1, 255))
self.assertEqual(extrema("P"), (0, 225)) # fixed palette
self.assertEqual(extrema("RGB"), ((0, 255), (0, 255), (0, 255)))
self.assertEqual(extrema("RGBA"), ((0, 255), (0, 255), (0, 255), (255, 255)))
self.assertEqual(extrema("CMYK"), ((0, 255), (0, 255), (0, 255), (0, 0)))
self.assertEqual(extrema("I;16"), (0, 255))
self.assertEqual(extrema("I;16"), (1, 255))
def test_true_16(self):
with Image.open("Tests/images/16_bit_noise.tif") as im:

6
Tests/test_image_histogram.py
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@ -8,9 +8,9 @@ class TestImageHistogram(PillowTestCase):
return len(h), min(h), max(h)
self.assertEqual(histogram("1"), (256, 0, 10994))
self.assertEqual(histogram("L"), (256, 0, 638))
self.assertEqual(histogram("I"), (256, 0, 638))
self.assertEqual(histogram("F"), (256, 0, 638))
self.assertEqual(histogram("L"), (256, 0, 662))
self.assertEqual(histogram("I"), (256, 0, 662))
self.assertEqual(histogram("F"), (256, 0, 662))
self.assertEqual(histogram("P"), (256, 0, 1871))
self.assertEqual(histogram("RGB"), (768, 4, 675))
self.assertEqual(histogram("RGBA"), (1024, 0, 16384))

6
Tests/test_imagecolor.py
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@ -165,14 +165,14 @@ class TestImageColor(PillowTestCase):
self.assertEqual(0, ImageColor.getcolor("black", "L"))
self.assertEqual(255, ImageColor.getcolor("white", "L"))
self.assertEqual(162, ImageColor.getcolor("rgba(0, 255, 115, 33)", "L"))
self.assertEqual(163, ImageColor.getcolor("rgba(0, 255, 115, 33)", "L"))
Image.new("L", (1, 1), "white")
self.assertEqual(0, ImageColor.getcolor("black", "1"))
self.assertEqual(255, ImageColor.getcolor("white", "1"))
# The following test is wrong, but is current behavior
# The correct result should be 255 due to the mode 1
self.assertEqual(162, ImageColor.getcolor("rgba(0, 255, 115, 33)", "1"))
self.assertEqual(163, ImageColor.getcolor("rgba(0, 255, 115, 33)", "1"))
# Correct behavior
# self.assertEqual(
# 255, ImageColor.getcolor("rgba(0, 255, 115, 33)", "1"))
@ -180,5 +180,5 @@ class TestImageColor(PillowTestCase):
self.assertEqual((0, 255), ImageColor.getcolor("black", "LA"))
self.assertEqual((255, 255), ImageColor.getcolor("white", "LA"))
self.assertEqual((162, 33), ImageColor.getcolor("rgba(0, 255, 115, 33)", "LA"))
self.assertEqual((163, 33), ImageColor.getcolor("rgba(0, 255, 115, 33)", "LA"))
Image.new("LA", (1, 1), "white")

4
src/PIL/ImageColor.py
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@ -134,7 +134,9 @@ def getcolor(color, mode):
if Image.getmodebase(mode) == "L":
r, g, b = color
color = (r * 299 + g * 587 + b * 114) // 1000
# ITU-R Recommendation 601-2 for nonlinear RGB
# scaled to 24 bits to match the convert's implementation.
color = (r * 19595 + g * 38470 + b * 7471 + 0x8000) >> 16
if mode[-1] == "A":
return (color, alpha)
else:

3
src/libImaging/Convert.c
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@ -44,7 +44,8 @@
#define L(rgb)\
((INT32) (rgb)[0]*299 + (INT32) (rgb)[1]*587 + (INT32) (rgb)[2]*114)
#define L24(rgb)\
((rgb)[0]*19595 + (rgb)[1]*38470 + (rgb)[2]*7471)
((rgb)[0]*19595 + (rgb)[1]*38470 + (rgb)[2]*7471 + 0x8000)
#ifndef round
double round(double x) {