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Re: Label Region trouble [message #38006 is a reply to message #38000]

Tue, 10 February 2004 11:02

btt
Messages: 345
Registered: December 2000

Senior Member

Nuno Oliveira wrote:
> I'm almost shooting myself! Every time I think I'm reaching a solution I
> have a new problem! And this one is really something.
>
>
>
> The issue is that if find a boundary of ROI using Label Region before I don'
> t get the pixels that are on the borders of the image. This is really
> strange, I don't what Label Region does and even I can't find the code (is
> it in the IDL library? I don't find it!)
>

Hello,

Yes, it is a bit aggravating. The Label_Region function treats the
boundary of the image as background. Here's the blurb on the input
argument from the documentation....

" A n-dimensional image to be labeled. Data is converted to integer type
if necessary. Pixels at the edges of Data are considered to be zero."

The function below will work for 2d images.

FUNCTION MY_LABEL_REGION, data, _Extra = extra

Sz = Size(data)
dim = Sz[1:Sz[0]]
d = Make_Array(dim+2, value = 0, type = Sz[Sz[0]+1])

d[1,1] = data
mask = LABEL_REGION(d, _Extra = extra)

Return, mask[1:dim[0], 1:dim[1]]
END

If you have a lot of blobs within an image, you might prefer to use the
HISTOGRAM function with REVERSE_INDICES to navigate around the blobs.
It will save repeated calls to WHERE which has to search the entire array.

Ben

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[Message index]

		Re: Label Region trouble By: btt on Wed, 11 February 2004 07:26
		Re: Label Region trouble By: Nuno Oliveira on Wed, 11 February 2004 07:09
		Re: Label Region trouble By: Nuno Oliveira on Wed, 11 February 2004 06:28
		Re: Label Region trouble By: btt on Tue, 10 February 2004 11:02

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