<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hi Amitesh,<br>
<br>
I agree with Jens: opening is erode followed by dilate. Maybe I am
mistaken.<br>
<br>
As far as noise removal and minimum erosion followed by maximum
dilation.<br>
<br>
While erosion can be used to eliminate small clumps and salt noise, it
has the big
disadvantage that it will affect<em></em> all foreground pixels
indiscriminately. Opening gets around this by performing both an
erosion and a dilation on the image. <br>
<br>
If you use Binary dilate with minimum erosion and maximum dilation, ie
different sized structuring elements, idempotency is lost (ie further
opertations of opening on the same
image will start having an effect closer to dilation rather than have
no effect). Some regions will start merging with each other.<br>
<br>
Maybe I am missing the point.<br>
<br>
thanks<br>
karthik<br>
<br>
Amitesh Agarwal wrote:
<blockquote cite="middd63bb7905010508302eb0eaac@mail.gmail.com"
type="cite">
<pre wrap="">Hi Jens,
Well if you refer to the book "Digital Image Processing" by Rafeal C.
Gonzalez & Richard E. Woods Section 9.2 & 9.3 specifically 9.3 It says
"Dilation expands an image and erosion shrinks it ........ Opening
Generally Smoothes the contour of an object, breaks narrow isthumuses
and eliminates thin protrusion. Closing also tends to smooth sections
of countour, as opposed to opening, it generally fuses narrow breaks
and long thin gulfs, eliminates small holes, and fills gaps in the
countour"
Moreover in certain situtations, as I have experienced while working
with binary image of skull and brain, a combination of BinaryErode
and BinaryDilate doesn't completly solve the problem of opening and
closing in some regions. Some regions actually start merging with each
other if I use a bigger BinaryStructuralBallBearingElement (5x5x5) for
better removal of undesirable noise in the data in the order first
BinaryErode and then BinaryDilate with minimum erosion and maximum
dilation for best results.
I hope this clarifies my point.
Amitesh
On Wed, 5 Jan 2005 08:47:04 +0100, Jens Eickmeyer <a class="moz-txt-link-rfc2396E" href="mailto:eickmeyer@gmail.com"><eickmeyer@gmail.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi!
On Tue, 4 Jan 2005 15:40:43 -0600, Amitesh Agarwal
<a class="moz-txt-link-rfc2396E" href="mailto:amiteshagarwal@gmail.com"><amiteshagarwal@gmail.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">4) Opening and closing operation in a binary image
I just wanted to know if there is any filter present in ITK for
performing opening and closing operation in a given Binary Image. It
is my understanding that BinaryErode and BinaryDilate do similar
operation in effect but not exactly the same.
</pre>
</blockquote>
<pre wrap="">I haven't found such a filter, too. I use BinaryDilate and BinaryErode
to apply closing to a binary image. But why are you thinking that this
hasn't the same effect? Closing is just a dilation followed by am
erosion and opening is just an erosion followed by a dilation. If
BinaryErode and BinaryDilate work correctly - and I think we can
assume this - the combined execution should lead to the right results.
Jens
</pre>
</blockquote>
<pre wrap=""><!---->_______________________________________________
Insight-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Insight-users@itk.org">Insight-users@itk.org</a>
<a class="moz-txt-link-freetext" href="http://www.itk.org/mailman/listinfo/insight-users">http://www.itk.org/mailman/listinfo/insight-users</a>
</pre>
</blockquote>
<br>
</body>
</html>