I believe it is globally understood (to those skilled in the art ;) that
such routines label the connected foreground regions (nonzero). If you
want to label the connected background regions just invert the image.
There might be some additional issues with the way connectedness is
usually used for foreground vs background (8-connectedness vs
4-connectedness etc).
Christian
Vladimir Radulovski wrote:
Hey guys - we solved the issue - the problem was that my test image
had only two connected components - one of 0s and one of 1s - in the
help there was not mentioned that cc8compt numbers only the regions
with the 1s - leaving the 0s unchanched - i.e
from this ->
[
[10000]
[00011]
[11000]
[00001]
]
with cc8compt you get this ->
[
[10000]
[00022]
[33000]
[00004]
]
So additional simple tricks are needed to get the 0s numbered too
(differently from the 1s)
I suggest showing this example in the manual of the cc8compt function
- the way it is now is quite unclear...
2007/5/7, [EMAIL PROTECTED] <[EMAIL PROTECTED]>:
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Today's Topics:
1. problem with the cc8compt routine from PDL::Image2D - need
help (Vladimir Radulovski)
2. Re: problem with the cc8compt routine from PDL::Image2D -
need help (Jarle Brinchmann)
----------------------------------------------------------------------
Message: 1
Date: Sun, 6 May 2007 11:56:21 +0300
From: "Vladimir Radulovski" <[EMAIL PROTECTED]>
Subject: [Perldl] problem with the cc8compt routine from PDL::Image2D
- need help
To: [email protected]
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi al - here is Vladimir from Bulgaria.
Tell me has any of the pdl users done things with cc8compt - I do this:
perldl>$im = rpic "b.gif" # the gif is a 2-colour
# after the rpic - I have a nice 20x20 piddle $im, but when i try
perldl> use PDL::Image2D # it loads the module
perldl> $segmented = cc8compt ($im)
I get in $segmented THE SAME VALUES as in $im - it does copying - not
- numbering the different connected components - HELP!
------------------------------
Message: 2
Date: Sun, 06 May 2007 11:03:06 +0100
From: Jarle Brinchmann <[EMAIL PROTECTED]>
Subject: Re: [Perldl] problem with the cc8compt routine from
PDL::Image2D - need help
To: Vladimir Radulovski <[EMAIL PROTECTED]>
Cc: [email protected]
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi Vladimir,
cc8compt works on a thresholded image, ie. one that has only values 0 or
1 (see also the documentation).
This means that you, depending on your needs, might have to do some
careful pre-processing. For gray-scale images with noise I would
normally first find the noise level, $sig, then create a thresholded
image as:
$tim = $im > 3.0*$sig;
(say, this is not always a good way to do it of course! :), then you
threshold using:
$label_im = cc8compt($tim);
That works fine. If you need to do thresholding based on colour values,
then you need to replace the simple > operation above with somewhat more
complex logic I'd assume.
Cheers,
J.
Vladimir Radulovski wrote:
> Hi al - here is Vladimir from Bulgaria.
>
> Tell me has any of the pdl users done things with cc8compt - I do this:
>
> perldl>$im = rpic "b.gif" # the gif is a 2-colour
>
> # after the rpic - I have a nice 20x20 piddle $im, but when i try
>
> perldl> use PDL::Image2D # it loads the module
> perldl> $segmented = cc8compt ($im)
>
> I get in $segmented THE SAME VALUES as in $im - it does copying - not
> - numbering the different connected components - HELP!
>
> _______________________________________________
> Perldl mailing list
> [email protected]
> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
------------------------------
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