Do not initialize image with zero dimension or when color is zero

[radarhere]

#9933 mentioned that

Pillow/Tests/test_image.py

Lines 574 to 577 in 7827507

	@timeout_unless_slower_valgrind(0.75)
	@pytest.mark.parametrize("size", ((0, 100000000), (100000000, 0)))
	def test_empty_image(self, size: tuple[int, int]) -> None:
	Image.new("RGB", size)

is intermittently failing on our CI.

I think

Pillow/src/PIL/Image.py

Lines 3234 to 3236 in 7827507

	if color is None:
	# don't initialize
	return Image()._new(core.new(mode, size))

can be adjusted to help.

[codspeed-hq]

Merging this PR will degrade performance by 56.95%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 602 untouched benchmarks
⏩ 335 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_allocate[1237x811-L]	1.1 ms	2.5 ms	-56.95%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing radarhere:new_size (0f4e203) with main (7827507)}

Footnotes

1. 335 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[akx]

I don't think this helps with the timeout on tall zero-width images.

core.fill(mode, size, color), paraphrased:

• im = ImagingNewDirty(mode, xsize, ysize)
• ImagingFill(im, ink_parsed_from_color)
• return PyImagingNew(im)

core.new(mode, size), paraphrased:

• im = ImagingNew(mode, xsize, ysize)
• return PyImagingNew(im)

ImagingNew and ImagingNewDirty are trampolines to ImagingNewInternal, which, paraphrased;

• im = ImagingNewPrologue(mode, xsize, ysize); which calls ImagingNewPrologueSubtype, which allocates the pointer array: im->image = (char **)calloc((ysize > 0) ? ysize : 1, sizeof(void *));

In fact, I think # don't initialize isn't a valid comment at all.

• EDIT: it hasn't been true for 7 to 13 years, depending, I investigated. #9960