![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/189772/image.png)
how can i remove the white object from binary image
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R G
am 13 Apr. 2018
Bearbeitet: Image Analyst
am 18 Apr. 2018
I have a image with my needed object (green) and the noise (white). I want to delete the noise but have no idea for that. anyone can help
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/189398/image.png)
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Gopichandh Danala
am 13 Apr. 2018
You can use regionprops to compute circularity, eccentricity, or use major axis and minor axis lengths to find required shape of blob.
I used major and minor axis:
img = logical(rgb2gray(imread('green.png')));
dilate_img = imdilate(img,strel('disk',2));
BW = bwlabel(dilate_img);
blobprops = regionprops(BW, 'MajorAxisLength','MinorAxisLength', 'Eccentricity');
allMajorAxisLength = [blobprops.MajorAxisLength];
allMinorAxisLength = [blobprops.MinorAxisLength];
allEccentricity = [blobprops.Eccentricity];
MajorbyMinor = allMajorAxisLength./allMinorAxisLength;
[B,I] = sort(MajorbyMinor);
BW2 = ismember(BW,I(1));
% Using eccentricity
% [B,I] = sort(allEccentricity); % eccentricity = 0: circle, = 1: line
% BW2 = ismember(BW,I(1));
figure,
subplot(131), imshow(img), title('Original');
subplot(132), imshow(BW), title('Label');
subplot(133), imshow(BW2), title('desired');
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/189772/image.png)
2 Kommentare
Gopichandh Danala
am 17 Apr. 2018
The answer is always based on your question. You specifically asked for the green object in your image, so I answered accordingly. For imdilate, ismember, check the documentation. The reason to use dilate in this case is to connect the objects on the right to make it as one. so, it's easy to identify it as not being a round object. To make this more generic to identify multiple regions which satisfy a certain threshold condition.
MajorbyMinor = allMajorAxisLength./allMinorAxisLength;
thresh_value = 4; % set a threshold value
indxs = MajorbyMinor < thresh_value;
% [B,I] = sort(MajorbyMinor);
BW2 = ismember(BW,find(indxs));
It all depends on your requirement. i.e. the shape, size of the object. Adjust the threshold value to meet your requirement.
Weitere Antworten (1)
Image Analyst
am 15 Apr. 2018
You didn’t say what was unique about the object but it looks like it might be the size of the bounding box. So why don’t you compute that with regionprops()?
2 Kommentare
Image Analyst
am 18 Apr. 2018
Bearbeitet: Image Analyst
am 18 Apr. 2018
Compute the bounding box.
labeledImage = bwlabel(binaryImage);
props = regionprops(labeledImage, 'BoundingBox');
Then decide which ones to keep, like if the width to height ratio is between 0.5 and 3, or whatever.
indexesToKeep = false(1, length(props));
for k = 1 : length(props)
width = props(k).BoundingBox(3);
height = props(k).BoundingBox(4);
if width/height > 0.5 || width/height < 3
% It's a fairly square box, so keep it.
indexesToKeep(k) = true;
end
end
% Extract just acceptable blobs
indexesToKeep = find(indexesToKeep);
binaryImage2 = ismember(labeledImage, indexesToKeep);
imshow(binaryImage2);
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