Use more points to find image bounds in moasics #444

Job	Run time
tests / Load tox environments	7s
tests / py38-test-oldestdeps (macos-latest)	15m 2s
tests / py39-test (macos-latest)	18m 17s
tests / py310-test (macos-latest)	15m 40s
tests / py38-test-oldestdeps (ubuntu-latest)	9m 47s
tests / py38-test (ubuntu-latest)	10m 38s
tests / py39-test (ubuntu-latest)	9m 54s
tests / py310-test (ubuntu-latest)	10m 4s
tests / py311-test-devdeps (ubuntu-latest)	12m 22s
tests / py38-test-oldestdeps (windows-latest)	15m 29s
tests / py39-test (windows-latest)	13m 20s
tests / py310-test (windows-latest)	18m 6s
publish	0s
	2h 28m 46s

Provide feedback