New submission from Zac Hatfield-Dodds <zac.hatfield.do...@gmail.com>:
As part of the Mentored Sprints at PyCon US, Marielle wrote some property-based tests [1] for the colorsys module [2], which found two bugs. Taking a YIQ color, converting to RGB, and back to YIQ can result in the Y coordinate varying by more 0.1 (where [0, 1] is the range of possible values). For example: (0.0 1.0 2.2204460492503136e-16) -> RGB -> (0.0 1.1102230246251568e-16 1.0) Taking an RGB color and converting though HSV-RBG-HSV can result in very different saturation values - up to having S1==0 and S2==1. For example: (0.0 1.0 2.2204460492503136e-16) -> RGB -> (0.0 1.1102230246251568e-16 1.0) You can reproduce additional examples and get error bounds from [3]. [1] https://pyfound.blogspot.com/2020/05/property-based-testing-for-python.html [2] https://docs.python.org/3/library/colorsys.html [3] https://github.com/Zac-HD/stdlib-property-tests/pull/13 ---------- components: Library (Lib) messages: 369197 nosy: Zac Hatfield-Dodds priority: normal severity: normal status: open title: Catastrophic loss of precision in colorsys module type: behavior versions: Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue40668> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
