The Alpha Coverage Thresholds in texture settings doesn't work as expected

A licensee reported that the Alpha Coverage Comparison doesn't work as expected.

He used this texture [Link Removed]and set the alpha of the Alpha Coverage Thresholds to 0.5.

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But he found that it doesn't work as expected, so he modified the code of GenerateSharpenedMipB8G8R8A8Templ in TextureCompressorModule.cpp, and did a comparison with the original method, as showed below.

On the left is the original method, on the right is the modified method, you could see that the chain fence is still clear in the middle distance and far distance after the modification.

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The difference is that the AlphaScale is calculated based on the source, but it should be calculated from the dest, after reading the code, I believe he is right about it.

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