Is there a function that removes objects binary image based only on their pixel area?

I want to maintain lines, so erode or close is out of the question. Planning on using region props and check each area region, but that seems slow and inefficient...

Tks

On Dec 15, 7:17=A0pm, "Ironic Prata" <lixodoiro...@hotmail.com> wrote:
> Is there a function that removes objects binary image based only on their=
 pixel area?
>
> I want to maintain lines, so erode or close is out of the question. Plann=
ing on using region props and check each area region, but that seems slow a=
nd inefficient...
>
> Tks
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You can use bwareaopen().  Despite the name it doesn't use a
morphological opening, but rather uses the regionprops method, that
you want to avoid.  I don't know of any faster methods.  Why do you
say it's slow?  It doesn't seem slow when I use it - just takes a
fraction of a second.  How large are your images, how many blobs are
in them, and how long is it taking on your computer?  Maybe you can
get a faster computer.

ImageAnalyst <imageanalyst@mailinator.com> wrote in message <99896c54-e824-4fc6-9b92-3eb8fa8c7704@x20g2000vbn.googlegroups.com>...
> On Dec 15, 7:17?pm, "Ironic Prata" <lixodoiro...@hotmail.com> wrote:
> > Is there a function that removes objects binary image based only on their pixel area?
> >
> > I want to maintain lines, so erode or close is out of the question. Planning on using region props and check each area region, but that seems slow and inefficient...
> >
> > Tks
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> You can use bwareaopen().  Despite the name it doesn't use a
> morphological opening, but rather uses the regionprops method, that
> you want to avoid.  I don't know of any faster methods.  Why do you
> say it's slow?  It doesn't seem slow when I use it - just takes a
> fraction of a second.  How large are your images, how many blobs are
> in them, and how long is it taking on your computer?  Maybe you can
> get a faster computer.

the problem is that this is to be used in a loop, so i want efficiency.

but at least that function will clear up the code. tks

On Dec 15, 9:28=A0pm, "Ironic Prata" <lixodoiro...@hotmail.com> wrote:
> the problem is that this is to be used in a loop, so i want efficiency.
> but at least that function will clear up the code. tks
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You're implying that the bwareaopen function is inefficient.  What's
the basis for saying that?  Do you have a more efficient method?  Why
is this method too slow for you?  Again, what kind of speed do you
require and what kind of speed are you getting?

Hi

Other possibility, aside the suggestion made by ImageAnalyst, is to use a small median filter. You can "efficiently" apply it multiple times in a loop.

Igor 

"Ironic Prata" <lixodoironic@hotmail.com> wrote in message <hg98tv$2m$1@fred.mathworks.com>...
> 
> Is there a function that removes objects binary image based only on their pixel area?
> 
> I want to maintain lines, so erode or close is out of the question. Planning on using region props and check each area region, but that seems slow and inefficient...
> 
> Tks

"Ironic Prata" <lixodoironic@hotmail.com> wrote in message <hg98tv$2m$1@fred.mathworks.com>...
> 
> Is there a function that removes objects binary image based only on their pixel area?
> 
> I want to maintain lines, so erode or close is out of the question. Planning on using region props and check each area region, but that seems slow and inefficient...
> 
> Tks

Like this:

stats = regionprops(binary, 'Area', 'PixelIdxList');
cleaned = binary;
for region = 1 : length(stats)
    if stats(region).Area < MIN_AREA
        cleaned(stats(region).PixelIdxList) = 0;
    end
end

I can guarantee this is REALLY fast! ;)