Both @cyanglaz and I have tried to generate the golden images for flutter/engine#17915. Although our locally generated images can pass the test locally, they fail in LUCI bots. It turns out that only images generated from @blasten 's Mac can let LUCI bots pass the test. According to Emmanuel, the golden images generated by me has no pixel difference with his images. But the test with my images somehow failed in his Mac and LUCI. This suggest that the pixel comparison in the test might be problematic.