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<div style="font-family: Consolas; font-size: medium; ">I noticed that the Modules directory for ITK 4.2 contains a Metricsv4</div>
<div style="font-family: Consolas; font-size: medium; ">subdirectory under the Registration module. From a bit of poking around, it</div>
<div style="font-family: Consolas; font-size: medium; ">looks like the intention of these metrics is threaded, faster versions of</div>
<div style="font-family: Consolas; font-size: medium; ">the original metrics by the same name. Since you've added a "v4" suffix to</div>
<div style="font-family: Consolas; font-size: medium; ">the original object names as an opt-in interface, I was curious what the</div>
<div style="font-family: Consolas; font-size: medium; ">expectation is in terms of compatibility with the original metrics. I'm</div>
<div style="font-family: Consolas; font-size: medium; ">particularly interested in how the behavior/numerics of:</div>
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<div style="font-family: Consolas; font-size: medium; ">itkMattesMutualInformationImageToImageMetricv4</div>
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<div style="font-family: Consolas; font-size: medium; ">And</div>
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<div style="font-family: Consolas; font-size: medium; ">itkMeanSquaresImageToImageMetricv4</div>
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<div style="font-family: Consolas; font-size: medium; ">Compare to the v3 versions of the same objects? Are these just threaded functions with the exact same behavior as far as numerics, or are there other functional differences in the metrics to be aware of?</div>
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<div style="font-family: Consolas; font-size: medium; ">- Alex.</div>
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