Hi Lynx,<br><br>Could you please list the colors of the blobs that surround the "dark red"<br>blob that you are concerned about ?<br><br>Just by looking at the image: blobs_ws03.tif<br><br>it is not obvious which of the blobs is the one that doesn't seem to <br>
produce the correct output.<br><br><br>Pixel coordinates (or an annotated image) will be very helpful too...<br><br><br> Thanks<br><br><br> Luis<br><br><br>--------------------------------------------<br><div class="gmail_quote">
On Sun, Jul 26, 2009 at 4:09 PM, <span dir="ltr"><<a href="mailto:lynx.abraxas@freenet.de">lynx.abraxas@freenet.de</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;">
Dear Dan Mueller,<br>
<br>
<br>
Thank You for Your quick reply with the examples.<br>
What I still wonder is why I don't get 2 when I ask the<br>
SignedDanielssonDistanceMap for squared distance output. Squared distances<br>
should be always integers (if I'm not mistaken) and should go in the tif<br>
unmodified (eg. 2).<br>
Anyway, I changed my intermediat pixel format to float and the output of a<br>
single white pixel is as I'd expect.<br>
However if I run my little watershed test program there is one blob (dark red<br>
blobl in blobs_ws03.tif) that is surrounded by four split blobs but itself is<br>
not split although it has some crease. I even made the effort to count the<br>
pixels by hand. The minima-line is 8 pixels off the rim in horizontal<br>
direction. Now accounting for the additional distance to the left up to the<br>
end of the minima-line I'd say the gray values should decrease further since<br>
the distanc to the left has to be added to the 8 pixels up or down.But still<br>
blobs_rm01.tif has just one minimum. Are my expectations wrong here?<br>
I ran my test prog like this for the pics in the tbz (h-min height= 0, all<br>
fully connectd):<br>
watershed05b blobs.tif blobs_sddm_01.vtk blobs_hm01.tif blobs_rm01.tif blobs_cc01.tif blobs_ws01.tif blobs_ws02.tif blobs_ws03.tif 0 1 1<br>
<br>
<br>
Thanks for hints or help<br>
Lynx<br>
<div><div></div><div class="h5"><br>
<br>
On 26/07/09 15:33:53, Dan Mueller wrote:<br>
> Hi Lynx,<br>
><br>
> The SignedDanielssonDistanceMap will perform the distance computation<br>
> using real (ie. float/double) precision. If the output is integer (ie.<br>
> signed short in your case) it will cast the result. The corner pixels<br>
> (which you expect to be 2) are actual sqrt(2) = 1.414, which when cast<br>
> to signed short come out as 1.<br>
><br>
> Please find attached an input image for which the floating point<br>
> signed distance (InsideIsPositive=False) has been computed -- the<br>
> result is as expected.<br>
><br>
> HTH<br>
><br>
> Cheers, Dan<br>
><br>
> 2009/7/26 <<a href="mailto:lynx.abraxas@freenet.de">lynx.abraxas@freenet.de</a>>:<br>
> > Hello!<br>
> ><br>
> ><br>
> > Using the SignedDanielssonDistanceMap and squared distances (signed short as<br>
> > output) I wonder why a distance of 2 has the same grey value as the distance<br>
> > 1.<br>
> > eg. input image (x white, space black):<br>
> > | |<br>
> > | x |<br>
> > | |<br>
> ><br>
> > The relative distance map I get looks like:<br>
> > |111|<br>
> > |1x1|<br>
> > |111|<br>
> ><br>
> > I'd expect:<br>
> > |212|<br>
> > |1x1|<br>
> > |212|<br>
> ><br>
> > Is my expactation wrong or is the SignedDanielssonDistanceMapImageFilter not<br>
> > that accurate? Would flout as output and not squared distances exchage the 2s<br>
> > by sqrt(2)?<br>
> ><br>
> > Thanks for any hint or help<br>
> > Lynx<br>
<br>
<br>
<br>
<br>
<br>
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