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Thread Subject:
Is IMERODE susceptible to signal pixel noise?

Subject: Is IMERODE susceptible to signal pixel noise?

From: JohnMC

Date: 9 Sep, 2010 19:48:05

Message: 1 of 4

My purpose is two-fold:
1. find local minimum area with range of 10-20 pixels,
2. find minimum pixel within this area

if I use imerode, would it be influenced by a single pixel noise with very low value but at wrong position?

Subject: Is IMERODE susceptible to signal pixel noise?

From: Sean

Date: 9 Sep, 2010 20:00:28

Message: 2 of 4

"JohnMC " <nirmathink@gmail.com> wrote in message <i6bdll$k5o$1@fred.mathworks.com>...
> My purpose is two-fold:
> 1. find local minimum area with range of 10-20 pixels,
> 2. find minimum pixel within this area
>
> if I use imerode, would it be influenced by a single pixel noise with very low value but at wrong position?

I really don't understand what you're trying to do. What is single pixel at wrong position? Do you want a minimum that is forced to be in a trough of a certain size?
If you want to find the minimum in every 10 to 20 pixels take a peak at BLKPROC().

IMERODE is used to morphologically erode binary images (i.e. make true blobs smaller); this doesn't sound like a proper application.

Subject: Is IMERODE susceptible to signal pixel noise?

From: Sean

Date: 9 Sep, 2010 20:02:21

Message: 3 of 4

"JohnMC " <nirmathink@gmail.com> wrote in message <i6bdll$k5o$1@fred.mathworks.com>...
> My purpose is two-fold:
> 1. find local minimum area with range of 10-20 pixels,
> 2. find minimum pixel within this area
>
> if I use imerode, would it be influenced by a single pixel noise with very low value but at wrong position?

I really don't understand what you're trying to do. What is single pixel at wrong position? Do you want a minimum that is forced to be in a trough of a certain size?
If you want to find the minimum in every 10 to 20 pixels take a peak at BLKPROC().

IMERODE is used to morphologically erode binary images (i.e. make true blobs smaller); this doesn't sound like a proper application.

Subject: Is IMERODE susceptible to signal pixel noise?

From: ImageAnalyst

Date: 9 Sep, 2010 20:46:39

Message: 4 of 4

Maybe you might want to run your image through a 3x3 median filter to
get rid of single pixel noise. Of course that will also get rid of
local minima that are valid. In that case, maybe you can try a sigma
filter or a k-nearest neighbor filter, or even a bilateral filter
(Google them), to make sure you're removing only real outlier noise.
Just do whatever works for you. What is your final, ultimate goal,
after you've done the erosion successfully?

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