Filling objects that share a border
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Hi,
I have a question about filling in objects that share a border with the perimeter of an image.
Consider a case such as the one shown at: http://i43.tinypic.com/2nq9ua.jpg. If I run the imfill function to fill in the holes, I don’t get the five objects that touch the border of the image filled (I have pointed out the specific areas I am talking about, in this image: http://i41.tinypic.com/5afeo4.jpg).
Is there any strategy I could follow to fill holes in those areas that are outlined using the arrows?
Thanks in advance!
1 个评论
Ashish Uthama
2013-9-6
Good question (nice image!)
采纳的回答
Image Analyst
2013-9-4
编辑：Image Analyst
2013-9-5
0 个投票
- Binarize and Invert the image: binaryImage = grayImage <128
- Call imfill(binaryImage, 'holes')
- call regionprops(binaryImage, 'BoundingBox') asking for bounding box
- Look at the 4 sides of all the bounding boxes looking for any objects that share any bounding box side coordinate.
Give it a shot.
3 个评论
Image Analyst
2013-9-5
OK, no response so I'm guessing that you couldn't do it, so I did it for you. Try this code (be sure to change the folder and filename):
clc; % Clear the command window.
clearvars
close all;
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Read in a standard MATLAB gray scale demo image.
folder = 'C:\Users\Alexius\Documents';
baseFileName = '2nq9ua.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
% File doesn't exist -- didn't find it there. Check the search path for it.
fullFileName = baseFileName; % No path this time.
if ~exist(fullFileName, 'file')
% Still didn't find it. Alert user.
errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
uiwait(warndlg(errorMessage));
return;
end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[rows, columns, numberOfColorBands] = size(grayImage);
if numberOfColorBands > 1
% It's not really gray scale like we expected - it's color.
% Convert it to gray scale by taking only the green channel.
grayImage = grayImage(:, :, 2); % Take green channel.
end
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off')
% Binarize and Invert the image:
binaryImage = grayImage < 128;
% Display the image.
subplot(2, 2, 2);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);
% Call imfill(binaryImage, 'holes')
binaryImage = imfill(binaryImage, 'holes');
% Display the image.
subplot(2, 2, 3);
imshow(binaryImage, []);
title('Filled Binary Image', 'FontSize', fontSize);
% Get areas
labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Area')
% Sort based on areas
[sortedAreas, sortIndexes] = sort([measurements.Area], 'Descend')
% Get rid of largest one, which is the background.
% 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, sortIndexes(2:end));
% Display what we retained.
% Display the image.
subplot(2, 2, 4);
imshow(keeperBlobsImage, []);
title('Border blobs', 'FontSize', fontSize);
% Get bounding boxes of the border blobs. Need to relabel again.
[labeledImage, numberOfBlobs] = bwlabel(keeperBlobsImage);
measurements = regionprops(labeledImage, 'BoundingBox', 'Centroid')
% Loop over blobs, labeling them with text.
hold on;
for b1 = 1 : numberOfBlobs
x = measurements(b1).Centroid(1);
y = measurements(b1).Centroid(2);
text(x, y, num2str(b1));
end
% Loop over blobs, comparing each blob to the other blobs
for b1 = 1 : numberOfBlobs
boundingBox1 = measurements(b1).BoundingBox;
x1 = [boundingBox1(1), boundingBox1(1) + boundingBox1(3)]
y1 = [boundingBox1(2), boundingBox1(2) + boundingBox1(4)]
for b2 = 1 : numberOfBlobs
if b2 == b1
continue;
end
boundingBox2 = measurements(b2).BoundingBox;
x2 = [boundingBox2(1), boundingBox2(1) + boundingBox2(3)]
y2 = [boundingBox2(2), boundingBox2(2) + boundingBox2(4)]
% See if they share the top border
if y1(1) == y2(1)
message = sprintf('Blob %d shares the top border with blob #%d', b1, b2);
uiwait(msgbox(message));
end
% See if they share the bottom border
if y1(2) == y2(2)
message = sprintf('Blob %d shares the bottom border with blob #%d', b1, b2);
uiwait(msgbox(message));
end
% See if they share the left border
if x1(1) == x2(1)
message = sprintf('Blob %d shares the left border with blob #%d', b1, b2);
uiwait(msgbox(message));
end
% See if they share the right border
if x1(2) == x2(2)
message = sprintf('Blob %d shares the right border with blob #%d', b1, b2);
uiwait(msgbox(message));
end
end
end
msgbox('Done with demo. Thanks ImageAnalyst!');
alexius
2013-9-5
alexius
2013-9-5
更多回答（1 个）
Anand
2013-9-6
0 个投票
Steve Eddins just posted about this. Here's an alternative approach:
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