MATLAB: Can I make bwareafilt keep any ties for n-th place

bwareafilt()image processingImage Processing Toolbox

I've been using bwareafilt, but keep getting warnings that there are ties for n-th place, and that the ties were not selected. Is there any way to make it keep any ties for n-th place?

Best Answer

Please post your binary image where this happens. Also state the criteria where you'd delete one. For example, if you take the two largest blobs and they are both exactly 10,000 pixels and it keeps them both, then do you just want to randomly select one for deletion? Or just delete the one on top (or left, right, bottom)?

Related Solutions

MATLAB: Extract the INNER white region of an image with black and white intersection.

First of all you don't need imclearborder because there is no part of your blob that touches the border. And after bwareafilt() you're probably still getting the original blob because some of the outer blobs are touching your inner blob by having the corners of the pixels touch. The default for bwareafilt() is 8-connected, which considers blobs touching on the diagonal to be the same blob. You should specify the "4-connected" option so that a blob is only connected if it's fully touching on the top, bottom, left, or right (not the diagonal/corner).

MATLAB: Remove parts from Image and Fill Parts

Pretty easy. Threshold, fill holes, take the 3 largest.

Solution below. Adapt as needed.

% Initialization steps.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 14;
filename = fullfile(pwd, 'image_1.jpg');
grayImage = imread(filename);
if ndims(grayImage) == 3
	% It's really an RGB image, not a gray scale image.  
	% Convert to gray scale
	grayImage = rgb2gray(grayImage);
end
subplot(2, 3, 1);
imshow(grayImage, []);
title('Original Image', 'FontSize', fontSize);
% Threshold
subplot(2, 3, 2);
imhist(grayImage);
grid on;
title('Histogram', 'FontSize', fontSize);
mask = grayImage < 128; % or whatever value works
subplot(2, 3, 3);
imshow(mask, []);
title('Initial Binary Image', 'FontSize', fontSize);
% Fill Holes
mask = imfill(mask, 'holes');
subplot(2, 3, 4);
imshow(mask, []);
title('After holes filled', 'FontSize', fontSize);
% Take 3 largest blobs then invert intensity.
mask = ~bwareafilt(mask, 3);
subplot(2, 3, 5);
imshow(mask, []);
title('Final Image Showing 3 Largest', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: Extract the INNER white region of an image with black and white intersection.

MATLAB: Remove parts from Image and Fill Parts

Related Question