removing objects which have area greater and lesser than some threshold areas and extracting only the objects which have the area in between
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Hi, I am doing a project on nighttime vehicle detection. I have extracted bright objects from the input traffic image.I have to remove smaller objects(noise) and larger objects(reflections) when compared to vehicle headlight objects. I have removed small objects using "sterl" function. How can i remove larger objects? Please help me in extracting based on the area of these objects. I have to extract only the in between area objects.
Thank you sir.
댓글 수: 4
Amrutha c
2019년 7월 25일
how to extract the bright objects(segmentation using adaptive thresholding) like head light during night time driving conditions using matlab code
Image Analyst
2019년 7월 25일
Amrutha, start your own question, and attach your own image. You can threshold to find the brightest things. See my Image Segmentation Tutorial in My File Exchange
채택된 답변
Teja Muppirala
2012년 8월 21일
Given some image, for example (just to make a random image):
I = conv2(randn(500),ones(10)) > 10;
imshow(I);
To keep only objects between, say, 30 pixels and 50 pixels in area, you can use the BWAREAOPEN command, like this:
LB = 30;
UB = 50;
Iout = xor(bwareaopen(I,LB), bwareaopen(I,UB));
figure, imshow(Iout);
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Jorge Quid
2020년 8월 29일
Mine too! By the way, thank you for all the image-related content, it helps a lot!
추가 답변 (2개)
Image Analyst
2012년 8월 21일
편집: Image Analyst
2012년 8월 21일
You can use the ismember() function. Look at this snippet adapted from my BlobsDemo image segmentation tutorial http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862. Don't worry - it's only a few lines. It just looks long because of all the comments. Read the comments. They are quite informative and instructive.
% Now I'll demonstrate how to select certain blobs based using the ismember function.
% Let's say that we wanted to find only those blobs
% with an area between 1500 and 20000 pixels.
allBlobAreas = [blobMeasurements.Area];
% Get a list of the blobs that meet our criteria and we need to keep.
allowableAreaIndexes = (allBlobAreas > 1500) & (allBlobAreas < 20000);
% That's a logical map of what indexed acceptable blobs are at.
% Like 0 0 1 0 1 0 0 1 1 0 0 1 0 1 0 0 1
% We need the actual index, like blobs #3, 5, 8, 9, 12, 14, and 17
% (to use the above logical array as an example).
keeperIndexes = find(allowableAreaIndexes);
% Extract only those blobs that meet our criteria, and
% eliminate those blobs that don't meet our criteria.
% Note how we use ismember() to do this.
keeperBlobsImage = ismember(labeledImage, keeperIndexes);
% Re-label with only the keeper blobs kept.
newLabeledImage = bwlabel(keeperBlobsImage, 8); % Label each blob so we can make measurements of it
% Now we're done. We have a labeled image of blobs that meet our specified criteria.
imshow(newLabeledImage , []);
title('"Keeper" blobs');
Jürgen
2012년 8월 21일
Hi,
to get properties from areas of blob in the image You have to do labeling first or transfrom to BW images then you can use STATS = regionprops(BW, properties) which give you all kind of information on the labeled objects. Area is one of them. regards,Jürgen
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Natalia Demidova
2021년 7월 28일
After extracting said largest blob (after initially using regionprops, specifically), how would you then remove it (i.e. correspond with the actual blob location?)
Image Analyst
2021년 7월 28일
@Natalia Demidova, try this:
largestBlob = bwareafilt(binaryImage, 1);
allExceptLargest = binaryImage & (~largestBlob); % Erase largest from the original
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