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<P><FONT SIZE=2 FACE="Arial">Dear list, </FONT>
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<P><FONT SIZE=2 FACE="Arial">I have a question on the use of masks in registration; I hope someone can help me.</FONT>
<BR><FONT SIZE=2 FACE="Arial">To define a custom region I use Metric->SetFixedImageMask(), as in ImageRegistration12.cxx. </FONT>
<BR><FONT SIZE=2 FACE="Arial">This seems to work fine; the IsInside() in the metric gives points in the masked region.</FONT>
<BR><FONT SIZE=2 FACE="Arial">However, there is one thing I do not understand: I get _very_ different results when setting the</FONT>
<BR><FONT SIZE=2 FACE="Arial">Registration->SetFixedImageRegion() to the entire image or when using, for example, the bounding</FONT>
<BR><FONT SIZE=2 FACE="Arial">box around the mask; even when numberofspatialsamples set to the total number of pixels of the masked</FONT>
<BR><FONT SIZE=2 FACE="Arial">area. I would expect that using a larger region would be (possibly much) slower, but not different, from using</FONT>
<BR><FONT SIZE=2 FACE="Arial">a smaller region, since in both cases numberofspatialsamples points are taken<I> inside</I> the masked region.</FONT>
<BR><FONT SIZE=2 FACE="Arial">So, I was wondering whether my assumptions were wrong (and, in that case, why?)? If not, than at least I know</FONT>
<BR><FONT SIZE=2 FACE="Arial">that there is a coding error somewhere that results in the observed behaviour..</FONT>
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<P><FONT SIZE=2 FACE="Arial">I hope you can help.</FONT>
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<P><FONT SIZE=2 FACE="Arial">Regards,</FONT>
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<P><FONT SIZE=2 FACE="Arial">Ro.</FONT>
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<P><FONT SIZE=2 FACE="Arial"> </FONT>
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