Clamping color values to within [0, 1]

[azeey]

🦟 Bug fix

Toward #200

Summary

This removes the clamping of color values, but it doesn't yet enforce the invariant for channels being within [0, 1]. The best way to do that would be to throw an exception, but we don't do that anywhere in the gz-math codebase.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[azeey]

I've added enforcement of the color values range [0, 1] in 5f0ae54. Some of the test values needed to be updated because the clamping is different now: instead of dividing by 255 when a value is greater than 1, it's clamped to 1.

While I was trying to fix tests, I noticed that the functions that convert between RGB and YUV are not well defined. It's not clear what the input range is for YUV values. I also couldn't find a good reference for the equations used for the conversion. In fact, checking wikipedia, it looks like the math might be incorrect. As far as I can tell, these functions are not being used anywhere in Gazebo, so I propse we deprecate them.

[iche033]

the YUV conversion code matches one of the formula in this post: https://www.vbforums.com/showthread.php?728455-What-is-the-CORRECT-conversion-for-YUV-to-RGB.

the HSV conversion code seems to come from: https://stackoverflow.com/a/6930407

I tried a few online color converters using the values from our test and the results don't really match. I agree we should either fix the code or deprecate / remove it.

[azeey]

Yes, there seems to be many conventions around this and I don't think any of us are experts in this area. I'll deprecate it in a follow-up PR.