RFR: 8326027: [TEST_BUG]Comparing buffered images of white background frame fails in Mac

[Tejesh R]

On Mon, 9 Sep 2024 18:45:45 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> > > This is why I asked the question: does the comparison remain accurate without the need for tolerance if you use `Robot.createMultiResolutionScreenCapture` and use the highest resolution from the returned multi-resolution image?
> > 
> > 
> > I couldn't reproduce the issue neither with `Robot.createMultiResolutionScreenCapture` nor with `Robot.createScreenCapture` since the failure occurs intermittently, not able to say anything about using `Robot.createMultiResolutionScreenCapture` instead of `Robot.createScreenCapture` .
> 
> According to your report in JBS, the white color is not exactly white: `0xFFEE'EEEE`. White color has value of `0xFFFF'FFFF`.
> 
> However, it's also common on Macs (because of color profile applied?), I mean that the captured color value is the same as the value used for filling.
> 
> At the same time, I expect the color is the same across the entire frame surface. What we see is that there are variations. I wonder how many pixels on the image have different color, other than the first pixel.

I guess the number pixels that doesn't match might vary, can't be constant. We can get that from the failure image though, but since the issue is intermittent, can't conclude exactly.

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PR Comment: https://git.openjdk.org/jdk/pull/20760#issuecomment-2354441837