Anja:<br><br>Thanks for pointing this out, I just fixed the documentation.<br><br> itkHessian3DToVesselnessMeasureImageFilter.h -> new revision: 1.10<br><br>To clarify, bright tubular structures in a dark background will have two eigen values that are very negative and one that is close to zero. Regarding parameter settings, the alpha_1 and 2 values are explained in the reference that's listed on the doxygen doc.<br>
<br><br>Thanks<br>--<br>karthik<br><br><br><br><div class="gmail_quote">On Mon, Jul 12, 2010 at 9:07 PM, Anja Ende <span dir="ltr"><<a href="mailto:anja.ende@googlemail.com">anja.ende@googlemail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hello everyone,<br>
<br>
I am trying to use the Hessian3DToVesselnessMeasureImageFilter to<br>
extract possible vessels from an MRA image. However, I am a bit<br>
confused as to the parameters to use for the filter. So, the<br>
documentation says:<br>
<br>
"The filter takes as input an image of hessian pixels and preserves<br>
pixels that have eigen values lambda_3 close to 0 and lambda_2 and<br>
lambda_1 as large negative values. (for bright tubular structures).<br>
<br>
However, later it goes on to say that:<br>
<br>
"Bright tubular structures will have low lambda_1 and large negative<br>
values of lambda_2 and lambda_3."<br>
<br>
I am not sure which one is correct.<br>
<br>
Does someone know which range of alpha_1 and alpha_2 should I try<br>
playing with when looking at MRA images where the vessels appear as<br>
bright structures?<br>
<br>
Cheers,<br>
<br>
Anja<br>
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