<html><div style='background-color:'><DIV class=RTE>Hello Luis,</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>I have been experimenting with the Affine transform along with viola-wells imagetoimagemutualinformation and mattesmutual information metrics.</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>The affine transform which consists of 9(rotation, scaling, shearing) + 3 translation is a 12 parameter transform. Adopting rigid constraints and 3 parameters 3(rotation) + 3(translation) to define the transformation, </DIV>
<DIV class=RTE>i am not sure of how to reduce the 12 parameters to 6, Ashburner and Friston (SPM people) suggest a method in ther Spatial registration paper. </DIV>
<DIV class=RTE>I am right now, weighting the rotation optimizer scales way higher than the translation optimizer scales. </DIV>
<DIV class=RTE>The alternative would be to first determine the 3 translation paramters and then the rotation parameters.</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>I would be glad if you had any suggestions in defining and optimizing a 6 parameter transform under the rigit constraints</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>Warm regards,</DIV>
<DIV class=RTE>Raghu </DIV></div><br clear=all><hr> <a href="http://g.msn.com/8HMAENUS/2752??PS=47575">Express yourself with the new version of MSN Messenger! Download today - it's FREE!</a> </html>