<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><div>Hi Bradley,<br><br>Thanks for the information.<br><br>I got the doubt as my results change in the two cases (though by very small amount, initially ), i.e with and without using itkRGBToLuminanceImageFilter.<br>I feed the input images to registration filter, and the output parameters of registration change (in second decimal values) per iteration.<br><br>And over multiple iterations of the optimizer, I get a change of 2-3 pixels in translation parameters, and the angle also changes by 0.5 degrees, for a particular set of input images. All the other parameters involved remain constant in both the cases.<br><br>I want to know the correct method to follow.<br><br>Thanks,<br>Sharath Venkatesha<br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br><div
style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Bradley Lowekamp <blowekamp@mail.nih.gov><br><b><span style="font-weight: bold;">To:</span></b> Sharath Venkatesha <sharath20284@yahoo.com><br><b><span style="font-weight: bold;">Cc:</span></b> Insight users <insight-users@itk.org><br><b><span style="font-weight: bold;">Sent:</span></b> Wednesday, July 8, 2009 12:32:07 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Insight-users] RGB Input to ImageFileReader defined with 'unsigned char' type ?<br></font><br>
Hello Sharath,<div><br></div><div>This conversion is done through with itk::ConvertPixelBuffer:</div><div><span><a target="_blank" href="http://www.itk.org/Doxygen/html/classitk_1_1ConvertPixelBuffer.html">http://www.itk.org/Doxygen/html/classitk_1_1ConvertPixelBuffer.html</a></span></div><div><br></div><div>This class is responsible for doing all the conversions that occur when reading an image from a file into your itk::Image. When the types don't match it auto-magically converts the types. This enable one to read a file of chars into an itk::Image of floats with out any problems.</div><div><br></div><div>For you particular case it computes the luminance based on the RGB values to get "grey" pixels. The RGBToLuminance filter should give simular results as well. </div><div><br></div><div>Brad</div><div><br><div><div>On Jul 8, 2009, at 3:19 PM, Sharath Venkatesha wrote:</div><br class="Apple-interchange-newline"><blockquote
type="cite"><div><br>Hi,<br><br>I observed that it works, if I give RGB input image to a ImageFileReader defined with 'unsigned char' type. <br>Is the behaviour defined?Are there many approximations involved?<br><br>I generally use itkRGBToLuminanceImageFilter to convert RGB input images to grayscale, before performing registration.<br><br><br>Thanks,<br>Sharath<br><br><br><br><br>_____________________________________<br>Powered by <a rel="nofollow" target="_blank" href="http://www.kitware.com">www.kitware.com</a><br><br>Visit other Kitware open-source projects at<br><span><a target="_blank" href="http://www.kitware.com/opensource/opensource.html">http://www.kitware.com/opensource/opensource.html</a></span><br><br><span>Please keep messages on-topic and check the ITK FAQ at: <a target="_blank" href="http://www.itk.org/Wiki/ITK_FAQ">http://www.itk.org/Wiki/ITK_FAQ</a></span><br><br>Follow this link to subscribe/unsubscribe:<br><span><a
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