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 > 0I 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.
Prepared with OpenAI Codex assistance.
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 callscontain().I would expect
contain()to return a 10×1 image, andpad()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 fromround()toresize(). 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.pyfrom main at0a61c530aed1a2792c6a47674ac2b70753bfccbbloaded against the same installed Pillow core. No external image or network access is needed for the reproduction.Prepared with OpenAI Codex assistance.