ImageOps.contain and pad fail when a narrow image rounds to zero pixels
Nobody has claimed this yet.
Assessment
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Newbie friendliness
- 76/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Active
- Tech stack
- python
- Domain
- computer-vision
Research direction
Start in ImageOps.py at ImageOps.contain(), where the rounded calculated dimension is passed to resize(); inspect how ImageOps.pad() delegates to contain(). Reproduce the narrow and transposed cases from the issue, then verify that contain() preserves a one-pixel dimension and pad() places the result in the requested canvas without the zero-size error.
Written by the indexing model from the issue text.
Description
Resizing a narrow image with ImageOps.contain() can round the shorter dimension to zero, even when both requested dimensions are positive. ImageOps.pad() hits the same error because it calls contain().
from PIL import Image, ImageOps
image = Image.new("RGB", (100, 1), "red")
ImageOps.contain(image, (10, 10))
# ValueError: height and width must be > 0
ImageOps.pad(image, (10, 10))
# ValueError: height and width must be > 0
I would expect contain() to return a 10×1 image, and pad() to return that image within a 10×10 canvas. The transposed input, 1×100, fails too. A 20×1 input also fails at the half-pixel rounding boundary.
In contain(), the calculated dimension is passed directly from round() to resize(). Keeping that calculated dimension at least one pixel avoids the error.
Reproduced on Windows with Python 3.13.15 and Pillow 12.3.0, and with ImageOps.py from main at 0a61c530aed1a2792c6a47674ac2b70753bfccbb loaded against the same installed Pillow core. No external image or network access is needed for the reproduction.
- Dominant language
- Python
- Stars
- 13.8k
- Forks
- 2.5k
- Avg merge
- 2d 7h
- Merged PRs (30d)
- 91
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
More from python-pillow/Pillow
-
Documentation Font Rendering Third Party Framework
Difficulty 2/5 1-3 hours Newbie friendliness 78/100
python-pillow/Pillow#9907 · 2 comments ·
-
Documentation
Difficulty 2/5 1-3 hours Newbie friendliness 78/100
python-pillow/Pillow#9810 · 2 comments ·
-
License
Difficulty 2/5 1-3 hours Newbie friendliness 64/100
python-pillow/Pillow#9657 · 2 comments ·
-
Difficulty 2/5 1-3 hours Newbie friendliness 70/100
python-pillow/Pillow#9584 · 1 comment ·
-
Difficulty 3/5 1-2 days Newbie friendliness 68/100
python-pillow/Pillow#10028 · 3 comments · 1 reaction ·
All issues in python-pillow/Pillow
Similar issues
-
documentation help wanted
Difficulty 2/5 1-3 hours Newbie friendliness 90/100
-
Difficulty 2/5 1-3 hours Newbie friendliness 90/100
simonw/sqlite-utils#872 ·
-
Difficulty 2/5 1-3 hours Newbie friendliness 88/100
-
Difficulty 2/5 1-3 hours Newbie friendliness 82/100
-
Difficulty 2/5 1-3 hours Newbie friendliness 78/100