How to remove unconnected pixels or objects from an image

3 次查看（过去 30 天）

显示更早的评论

vidya 2014-1-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113073-how-to-remove-unconnected-pixels-or-objects-from-an-image

编辑： DGM 2023-2-14

采纳的回答： Walter Roberson

good day all.. i have an image with many unconnected vessels..of pixels i want to remove those pixels how an i do it?

采纳的回答

Walter Roberson 2014-1-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113073-how-to-remove-unconnected-pixels-or-objects-from-an-image#answer_121600

bwareaopen()

5 个评论
显示 3更早的评论隐藏 3更早的评论

Shri.s 2022-12-6

use bwareaopen(BW); to remove unexpected things...

Image Analyst 2022-12-6

在 MATLAB Online 中打开

@Shri.s, yes this was mentioned by @Walter Roberson and tried by @vidya. Did you click the link to show the hidden comments? The original poster said "even after using bwareaopen there are still some unconnected pixels in my image".

Now, since then, we don't need the code I attached above, we can use bwareafilt. For example to extract the 3 largest blobs we can do

bw = bwareafilt(bw, 3);

请先登录，再进行评论。

更多回答（1 个）

Image Analyst 2014-2-5

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113073-how-to-remove-unconnected-pixels-or-objects-from-an-image#answer_123317

test.m

OK, attached (below in blue text) is code that will get the largest network of vessels.

19 个评论
显示 17更早的评论隐藏 17更早的评论

Image Analyst 2014-2-6

编辑：Image Analyst 2014-2-6

在 MATLAB Online 中打开

You already set grayImage to BW2 which is already binary. So grayImage is actually a logical image with values of 0 and 1, not 0-255. So when you then threshold it:

binaryImage = grayImage > 100;

you get a totally black image - not what you want. Just skip the grayImage and binaryImage = grayImage>100 part and most of the other code in that test function - just get rid of those lines. Then put binaryImage in the argument list instead of bw2:

function test(binaryImage)
% Specify how many blobs to extract.
numberToExtract = 1;
%---------------------------------------------------------------------------
% Extract the largest area using our custom function ExtractNLargestBlobs().
% This is the meat of the demo!
biggestBlob = ExtractNLargestBlobs(binaryImage, numberToExtract);
%---------------------------------------------------------------------------
% Display the image.
subplot(2, 2, 4);
imshow(biggestBlob, []);
% Make the number positive again.  We don't need it negative for smallest extraction anymore.
numberToExtract = abs(numberToExtract);
caption = sprintf('Extracted Largest Blob');
title(caption, 'FontSize', fontSize);
msgbox('Done with demo!');

Quoc Anh Vu 2022-11-29

编辑：DGM 2023-2-14

Dear sir Image Analyst,

im working on extracting blood vessels on colposcopic image, but after segmentation, the result still has many unexpected objects, i want to keep structures i circled in below image, could you please help me to remove others , i've tried bwareafilt(), bwareaopen, but it didn't work. Thank you so much!

Image Analyst 2022-11-29

移动：DGM 2023-2-14

在 MATLAB Online 中打开

I'm not sure what about the 30 or so blobs you want to keep is unique about them. Evidently you say it's not their size, or at least not their size alone.

If you want all blobs within a certain distance of the large blobs, perhaps you can use bwareafilt to extract the largest blobs and then dilate the large blobs to get a larger region around them, then erase use imreconstruct to extract those blobs inside or connected to the large blob. Something like

se = strel('disk', 200, 8);
bigMask = imdilate(mask, se);
newMask = imreconstruct(bigMask, mask);

请先登录，再进行评论。

请先登录，再回答此问题。

类别

Sciences Biological and Health Sciences Biomedical Imaging Retinal Imaging

在 Help Center 和 File Exchange 中查找有关 Retinal Imaging 的更多信息

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by