How regionprops orders the regions ?
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Hello all,
I am confused how regionprops organizes the results? I have a picture that has 7 dark spots on it and need to calculate the area of each.Using regionprops, it shows the areas in pixels but in a confusing order! Is there anyway that I can get the results in an understandable order? like vertically or horizontally with the corresponding area?
Thank you Faraz
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Accepted Answer
Image Analyst
on 1 Jun 2017
The blobs are labeled/ordered/identified/numbered by bwconncomp() or bwlabel(). The order is column major order like most things in MATLAB.
So it goes down the image starting in the upper left pixel and goes down the first column. If it "sees" a pixel that's part of a blob that is not yet labeled, then it does a region growing to label that whole blob, even if it goes off into other rows and columns to the right or above. Then, once that blob is labeled, it continues on to find any other blobs. It proceeds like this top-to-bottom, left-to-right (i.e. column-by-column) until it has found and labeled every blob.
Does that explain it well enough?
More Answers (1)
Sippapas Mongkoldao
on 29 Aug 2020
Hi , Sorry for digging again .
I just wonder if I can order it by left-to-right , top-to-bottom and row-by-row instead of column-by-column ? So it can detect the top piece first , roll to the right and detect the next piece under it. Is it possible to use the regionprops on this condition or someone has an code to share with me ?
Thanks a lot
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Sippapas Mongkoldao
on 24 Oct 2020
Edited: Sippapas Mongkoldao
on 24 Oct 2020
This seem logically works. I'm trying now and facing some problems.
- This line is shown as error ''too few argument". What is happening?
thisBlob = ismember(labeledImage)
2. Do you have some ideas how to get rid of undesired blobs (the top-left one and the 2 in below-right)?
Appreciate!
Image Analyst
on 24 Oct 2020
- You need to pass k into ismember(): thisBlob = ismember(labeledImage, k)
- If the bad blobs are in known rows, then you can erase them
% Erase top part
mask(1:topRow, :) = false;
% Erase bottom part.
mask(bottomRow : end, :) = false;
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