ImageDraw.polygon produces the wrong image

What did you do?

Drew a polygon with PIL's Image and ImageDraw modules

What did you expect to happen?

The Polygon should look consistent without holes in the middle

What actually happened?

There are holes and gaps.

What are your OS, Python and Pillow versions?

OS: Ubuntu 22.04.5 LTS
Python: Python 3.10.12
Pillow: 11.0.0

Pillow 11.0.0
Python 3.10.12 (main, Nov  6 2024, 20:22:13) [GCC 11.4.0]
--------------------------------------------------------------------
Python executable is /home/ghrunner/venv/bin/python3
Environment Python files loaded from /home/ghrunner/venv
System Python files loaded from /usr
--------------------------------------------------------------------
Python Pillow modules loaded from /home/ghrunner/venv/lib/python3.10/site-packages/PIL
Binary Pillow modules loaded from /home/ghrunner/venv/lib/python3.10/site-packages/PIL
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 11.0.0
*** TKINTER support not installed
--- FREETYPE2 support ok, loaded 2.13.2
--- LITTLECMS2 support ok, loaded 2.16
--- WEBP support ok, loaded 1.4.0
--- JPEG support ok, compiled for libjpeg-turbo 3.0.4
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.2
--- ZLIB (PNG/ZIP) support ok, loaded 1.2.11
--- LIBTIFF support ok, loaded 4.6.0
--- RAQM (Bidirectional Text) support ok, loaded 0.10.1, fribidi 1.0.8, harfbuzz 10.0.1
*** LIBIMAGEQUANT (Quantization method) support not installed
--- XCB (X protocol) support ok

Code to reproduce the issue along with the images:

from PIL import Image, ImageDraw
import matplotlib.pyplot as plt

shape = (35, 15)
pts = [(31, 12), (30, 12), (28, 11), (28, 10), (26, 7), (23, 7), (22, 8), (22, 13), (22, 13), (21, 13), (20, 14), (18, 14), (17, 13), (15, 13), (13, 11), (10, 11), (8, 13), (5, 13), (4, 12), (3, 12), (1, 10), (1, 8), (3, 5), (4, 6), (5, 6), (6, 7), (6, 8), (8, 10), (9, 10), (10, 10), (10, 4), (13, 0), (19, 0), (21, 2), (21, 3), (22, 4), (23, 3), (24, 3), (26, 6), (26, 7), (31, 12)]
img = Image.new("L", shape, 0)
draw = ImageDraw.Draw(img)
draw.polygon(pts, fill=255)
img.save('polygon.png')

x, y = zip(*pts)
plt.figure(figsize=shape)
plt.plot(x, y, marker='o', linestyle='-', color='blue', markersize=5, label='Points and Lines')

plt.scatter(x, y, color='red', zorder=5, label='Points')

plt.title("Visualization of Points with Connections")
plt.xlabel("X-axis")
plt.ylabel("Y-axis")
plt.grid(True)
plt.legend()
plt.savefig('points.png')

I've created #8620 to resolve this. With it, Pillow creates this image.

I think the bug fix might have created new issues. Take a look at this example:

from PIL import Image, ImageDraw
import matplotlib.pyplot as plt

pts = [(183.5, 158.0), (184.0, 157.5), (185.0, 157.5), (186.0, 156.5), (189.0, 156.5), (190.00000390625002, 155.5), (192.0, 155.5), (192.99999609374998, 154.5), (195.0, 154.5), (196.0, 153.5), (196.99999609374998, 153.5), (198.00000390625002, 152.5), (199.0, 152.5), (200.0, 151.5), (200.99999609374998, 151.5), (202.00000390625002, 150.5), (203.0, 150.5), (204.99999609374998, 148.5), (206.00000390625002, 148.5), (207.5, 147.0), (207.5, 146.0), (208.49999609374998, 145.0), (208.49999609374998, 144.0), (209.49999609374998, 143.0), (209.49999609374998, 142.0), (210.50000390625002, 141.0), (210.50000390625002, 140.0), (211.5, 139.0), (211.5, 138.0), (211.0, 137.5), (207.0, 141.5), (206.00000390625002, 141.5), (205.50000390625002, 142.0), (205.50000390625002, 143.0), (204.49999609374998, 144.0), (204.49999609374998, 145.0), (202.00000390625002, 147.5), (201.49999609374998, 147.0), (201.49999609374998, 146.0), (202.50000390625002, 145.0), (202.00000390625002, 144.5), (200.99999609374998, 144.5), (200.49999609374998, 144.0), (200.49999609374998, 143.0), (200.0, 142.5), (199.0, 142.5), (198.50000390625002, 142.0), (198.50000390625002, 141.0), (202.50000390625002, 137.0), (202.50000390625002, 136.0), (203.5, 135.0), (203.5, 133.0), (204.99999609374998, 131.5), (206.00000390625002, 131.5), (207.0, 130.5), (208.0, 130.5), (208.99999609374998, 129.5), (211.0, 129.5), (212.0, 128.5), (218.00000390625002, 128.5), (218.50000390625002, 129.0), (218.50000390625002, 130.0), (213.50000390625002, 135.0), (214.00000390625002, 135.5), (215.0, 134.5), (216.0, 134.5), (216.99999609374998, 133.5), (218.00000390625002, 133.5), (219.0, 132.5), (220.0, 132.5), (220.99999609374998, 131.5), (222.00000390625002, 131.5), (223.000001953125, 130.5), (223.999998046875, 130.5), (226.00000390625002, 128.5), (227.000001953125, 128.5), (227.999998046875, 127.5), (232.99999609374998, 127.5), (234.00000390625002, 126.5), (235.000001953125, 126.5), (237.500005859375, 124.0), (235.999998046875, 122.5), (235.000001953125, 122.5), (234.500001953125, 123.0), (234.500001953125, 124.0), (232.99999609374998, 125.5), (230.00000390625002, 125.5), (229.500005859375, 125.0), (232.499998046875, 122.0), (231.999998046875, 121.5), (230.00000390625002, 121.5), (228.99999609374998, 122.5), (224.99999609374998, 122.5), (223.999998046875, 123.5), (220.99999609374998, 123.5), (220.0, 124.5), (216.99999609374998, 124.5), (216.0, 125.5), (212.99999609374998, 125.5), (212.0, 126.5), (208.99999609374998, 126.5), (208.0, 127.5), (206.00000390625002, 127.5), (204.99999609374998, 128.5), (203.0, 128.5), (202.00000390625002, 129.5), (200.99999609374998, 129.5), (190.00000390625002, 140.5), (189.0, 140.5), (187.0, 142.5), (186.0, 142.5), (185.0, 143.5), (184.0, 143.5), (182.0, 145.5), (181.0, 145.5), (178.0, 148.5), (177.0, 148.5), (172.5, 153.0), (173.0, 153.5), (174.0, 152.5), (175.0, 152.5), (176.0, 151.5), (177.0, 151.5), (177.4999921875, 152.0), (177.4999921875, 154.0), (179.0, 155.5), (181.0, 155.5), (182.5, 154.0), (182.5, 151.0), (181.5000078125, 150.0), (181.5000078125, 149.0), (182.0, 148.5), (183.0, 149.5), (184.0, 149.5), (186.0, 151.5), (188.0, 151.5), (188.5, 151.0), (188.5, 150.0), (187.5, 149.0), (187.5, 147.0), (185.4999921875, 145.0), (186.0, 144.5), (188.0, 144.5), (188.5, 145.0), (188.5, 146.0), (189.0, 146.5), (192.0, 146.5), (194.00000390625002, 144.5), (195.0, 144.5), (197.50000390625002, 147.0), (194.00000390625002, 150.5), (192.99999609374998, 150.5), (191.5, 152.0), (191.5, 153.0), (191.0, 153.5), (189.0, 153.5), (188.0, 154.5), (187.0, 154.5), (185.0, 156.5), (181.0, 156.5), (180.0, 157.5), (179.0, 157.5), (178.5, 158.0), (179.0, 158.5), (183.0, 158.5)]
pts = [(round(x), round(y)) for x, y in pts]
shape = (max([x for x, y in pts]) + 1, max([y for x, y in pts]) + 1)
img = Image.new("L", shape, 0)
draw = ImageDraw.Draw(img)
draw.polygon(pts, fill=255)
img.save('polygon.png')

x, y = zip(*pts)
plt.figure(figsize=shape)
plt.plot(x, y, marker='o', linestyle='-', color='blue', markersize=5, label='Points and Lines')

plt.scatter(x, y, color='red', zorder=5, label='Points')

plt.title("Visualization of Points with Connections")
plt.xlabel("X-axis")
plt.ylabel("Y-axis")
plt.grid(True)
plt.legend()
plt.savefig('points.png')`

There is a strip of pixels added to the mask which should not be there

Yet another example for debugging:

from PIL import Image, ImageDraw
import matplotlib.pyplot as plt

pts =  [(154.5, 189.0), (155.0, 188.5), (157.0, 188.5), (158.0, 187.5), (159.0, 187.5), (159.5, 187.0), (159.5, 186.0), (160.5, 185.0), (160.5, 182.0), (161.0, 181.5), (169.0, 181.5), (170.0, 182.5), (172.0, 180.5), (184.0, 180.5), (185.0, 179.5), (187.0, 179.5), (188.0, 178.5), (192.0, 178.5), (192.99999609374998, 177.5), (203.0, 177.5), (204.0, 176.5), (212.0, 176.5), (212.99999609374998, 177.5), (214.00000390625002, 177.5), (218.50000390625002, 182.0), (218.50000390625002, 183.0), (219.5, 184.0), (219.5, 185.0), (220.0, 185.5), (220.99999609374998, 185.5), (222.00000390625002, 184.5), (223.000001953125, 184.5), (223.999998046875, 183.5), (224.99999609374998, 183.5), (226.00000390625002, 182.5), (227.999998046875, 182.5), (228.99999609374998, 183.5), (231.000001953125, 183.5), (232.99999609374998, 181.5), (234.00000390625002, 181.5), (235.5, 180.0), (235.5, 178.0), (236.499998046875, 177.0), (236.499998046875, 176.0), (238.500001953125, 174.0), (238.500001953125, 173.0), (239.5, 172.0), (239.5, 168.0), (238.500001953125, 167.0), (238.500001953125, 165.0), (237.500005859375, 164.0), (237.500005859375, 163.0), (236.99999609374998, 162.5), (235.999998046875, 162.5), (235.000001953125, 161.5), (234.00000390625002, 161.5), (233.499994140625, 161.0), (233.499994140625, 160.0), (232.99999609374998, 159.5), (222.00000390625002, 159.5), (220.99999609374998, 158.5), (220.0, 158.5), (219.0, 157.5), (216.99999609374998, 157.5), (216.0, 156.5), (211.0, 156.5), (210.00000390625002, 155.5), (208.0, 155.5), (207.0, 154.5), (190.00000390625002, 154.5), (189.0, 155.5), (184.0, 155.5), (183.0, 156.5), (181.0, 156.5), (180.0, 157.5), (178.0, 157.5), (176.0, 159.5), (175.0, 159.5), (173.0, 161.5), (172.0, 161.5), (171.0, 162.5), (170.0, 162.5), (168.0, 164.5), (166.0, 164.5), (165.0, 165.5), (162.0, 165.5), (161.0, 166.5), (159.5, 165.0), (159.5, 164.0), (157.0, 161.5), (155.0, 161.5), (154.0, 160.5), (152.0, 160.5), (151.0, 161.5), (149.0, 161.5), (147.5, 163.0), (147.5, 166.0), (140.5, 173.0), (140.5, 175.0), (141.0, 175.5), (143.0, 175.5), (144.0, 174.5), (145.0, 174.5), (149.0, 170.5), (155.0, 170.5), (156.0, 169.5), (160.0, 169.5), (161.0, 170.5), (162.0, 169.5), (167.0, 169.5), (168.0, 168.5), (175.0, 168.5), (176.0, 167.5), (180.0, 167.5), (181.0, 166.5), (182.0, 166.5), (183.0, 167.5), (188.0, 167.5), (190.00000390625002, 169.5), (191.0, 169.5), (192.99999609374998, 167.5), (196.0, 167.5), (196.99999609374998, 168.5), (200.99999609374998, 168.5), (202.00000390625002, 169.5), (204.0, 169.5), (204.99999609374998, 170.5), (207.0, 170.5), (208.0, 171.5), (211.0, 171.5), (212.49999609374998, 173.0), (212.0, 173.5), (207.0, 173.5), (206.00000390625002, 174.5), (203.0, 174.5), (202.00000390625002, 175.5), (195.0, 175.5), (194.00000390625002, 176.5), (188.0, 176.5), (187.0, 175.5), (186.0, 175.5), (185.0, 174.5), (184.0, 174.5), (183.0, 175.5), (182.0, 175.5), (181.0, 176.5), (177.0, 176.5), (176.0, 175.5), (175.0, 175.5), (174.0, 174.5), (171.0, 174.5), (170.0, 175.5), (169.0, 174.5), (166.0, 174.5), (165.0, 173.5), (160.0, 173.5), (159.0, 174.5), (158.0, 174.5), (157.0, 175.5), (155.0, 175.5), (152.0, 178.5), (150.0, 178.5), (149.0, 177.5), (142.0, 177.5), (140.5, 179.0), (140.5, 180.0), (146.5, 186.0), (146.5, 187.0), (149.0, 189.5), (154.0, 189.5)]
pts = [(round(x), round(y)) for x, y in pts]
shape = (max([x for x, y in pts]) + 1, max([y for x, y in pts]) + 1)
img = Image.new("L", shape, 0)
draw = ImageDraw.Draw(img)
draw.polygon(pts, fill=255)
img.save('polygon.png')

x, y = zip(*pts)
plt.figure(figsize=shape)
plt.plot(x, y, marker='o', linestyle='-', color='blue', markersize=5, label='Points and Lines')

plt.scatter(x, y, color='red', zorder=5, label='Points')

plt.title("Visualization of Points with Connections")
plt.xlabel("X-axis")
plt.ylabel("Y-axis")
plt.grid(True)
plt.legend()
plt.savefig('points.png')

I was able to produce these issues by running
pip install git+https://github.com/python-pillow/Pillow
in my virtual environment after the recent merge to master.

I've created #8659.

As far as I can see, it resolves your issues. However, I imagine you have more examples apart from the three you've shared here, so I'm thinking of leaving it as draft until you give it your sign off. Would you be able to test the PR and let us know if it works?

With the recent changes in #8659, all my tests are passing. Thank you!

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ImageDraw.polygon produces the wrong image #8616

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ImageDraw.polygon produces the wrong image #8616

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What did you do?

What did you expect to happen?

What actually happened?

What are your OS, Python and Pillow versions?

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radarhere commented on Dec 23, 2024

SakuMyl commented on Jan 2, 2025

SakuMyl commented on Jan 2, 2025

SakuMyl commented on Jan 2, 2025

radarhere commented on Jan 4, 2025

SakuMyl commented on Jan 6, 2025

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