MATLAB: Extraction of rectangular blob from binary image

extractionimage processingImage Processing Toolboximage segmentation

i have a binary image having many blobs of different shapes. the one blob is full rectangle. now i want to extract the rectangular blob.

Best Answer

How about comparing length around the blob and length around the bounding box of the blob, like:

% sample blogs
I = imread('pillsetc.png');
Iblob = rgb2gray(I) > 200;
% measure perimeter and bounding box for each blob
stats = regionprops(Iblob,{'BoundingBox','perimeter'});
stats = struct2table(stats);
% extract the blob whose perimeter is close to round length of its bounding box
stats.Ratio = 2*sum(stats.BoundingBox(:,3:4),2)./stats.Perimeter;
idx = abs(1 - stats.Ratio) < 0.1;
stats(~idx,:) = [];
% show the result
imshow(Iblob);
hold on
for kk = 1:height(stats)
  rectangle('Position', stats.BoundingBox(kk,:),...
      'LineWidth',    3,...
      'EdgeColor',    'g',...
      'LineStyle',    ':');
end

Related Solutions

MATLAB: I am not getting the BoundingBox

See my Image Segmentation Tutorial where I demonstrate that: http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial---blobsdemo--

MATLAB: How to find x-y coordinates of minutia(end points , short ridges) of finger print image , and store it in matrix

Assuming the maximum 'area' (not 'length') of short ridges < 50 pixel, I think the following code can detect them.

% Read the image
I = imread('finger3.bmp');
BW = imbinarize(I);
% Measure region properties
stats = regionprops(~BW,{'Area','BoundingBox','PixelList'});
stats = struct2table(stats);
% Assuming the area of short ridge < 50 pixel
idx = stats.Area < 50;
stats = stats(idx,:);
% Show the detected short ridges
imshow(I)
hold on
for kk = 1:height(stats)
  rectangle('Position',stats.BoundingBox(kk,:),'EdgeColor','b')
  plot(stats.PixelList{kk}(:,1), stats.PixelList{kk}(:,2),'r.')
end

Best Answer

Related Solutions

MATLAB: I am not getting the BoundingBox

MATLAB: How to find x-y coordinates of minutia(end points , short ridges) of finger print image , and store it in matrix

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