Error using == Matrix dimensions must agree.

2014 10 14
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更新时间：2014 10 14
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I'm using the code below to find values, that is smaller than 500, but I get this error:
"Error using == Matrix dimensions must agree".
any one knows how to fix this problem?
thanks.
my code:
// BW is an image that I'm working on.
L = bwlabeln(BW);
s = regionprops(L);
Areal=[s.Area];
[~,dx] = find(Areal >= 500);
BW(L == dx)=0;
figure (5)
imagesc(BW)

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Adam
Adam 2014-10-14
Does the error message not indicate the line which caused it?

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Guillaume
Guillaume 2014-10-14

0 个投票

The error is because L is the size of the image and dx is any size up to the number of connected components in your image. The two sizes are never going to be the same, hence you can't use == for that.
First, your find should be:
idx = find(Area >= 500);
To then remove all the objects in BW that have an area greater than 500, use ismember:
BW(ismember(L, idx)) = 0;

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mehdi
mehdi 2014-10-14
Thank you Sir, It works! Much appreciated :-)
Guillaume
Guillaume 2014-10-14
编辑：Guillaume 2014-10-14
Good. if you're happy with the answer, then click on the green Accept this answer
mehdi
mehdi 2014-10-14
what if I want to substract Areal from idx.
can I do like this:
osteocytter = minus(ismember(Areal , idx));
Areal and Idx have to different size evry time. I suppose to do the same. (use ismember)???
Guillaume
Guillaume 2014-10-14
I'm afraid I don't understand what you're trying to do here.
Areal is an array of labelised objects area, while idx is the integer label of the objects that have an area greater than 500. Why would you want to subtract one from the other?
mehdi
mehdi 2014-10-14
编辑：Image Analyst 2014-10-14
I will find osteocytes that are less than 500.
Areal contains all ostecytes in image, while idx contains osteocytes greater than 500. If I substract idx from Areal, I will get all the other osteocytes that are smaller than 500.
my whole code:
[Filename, Pathname] = uigetfile(...
{'*.bmp;*.jpg;*.tif;*.png;*.gif','Image files (*.bmp;*.jpg;*.tif;*.png;*.gif)';...
'*.*','All file (*.*)'},...
'Select a file to open');
if ~isequal(Filename,0)
FileName = fullfile(Pathname,Filename);
else
error('User pressed cancel.');
end
im = imread(FileName);
figure (1)
imagesc(im);
I = imcrop;
imagesc(I);
level = graythresh(I);
BW = ~im2bw (I, level);
BW = imclearborder(BW);
BW = bwareaopen(BW,50);
BW = imfill(BW,'holes');
L = bwlabeln(BW);
s = regionprops(L,'Area');
Areal=[s.Area];
idx = find(Areal >= 500);
BW(ismember(L, idx)) = 0;
figure (2)
imagesc(BW);
x = size(Areal) - size(idx);
Antalosteocytter = x(1,2);
Iain
Iain 2014-10-14
This will remove the bits of Areal that correspond to what you've removed from your labelled image:
Areal(Areal >= 500) = [];
Guillaume
Guillaume 2014-10-14
Medhi,
No. Area contains the area of all osteocytes, while idx contains the label number of all osteocytes with an area greater than 500. The two things represent completely different concept.
To get the label number of the osteocytes smaller than 500, you can either
1) reverse the find criteria
idxsmall = find(Areal < 500);
2) compute the set difference (not subtract) between all the labels and idx
idxsmall = setdiff(idx, 1:max(L(:)));

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更多回答（1 个）

Image Analyst
Image Analyst 2014-10-14

0 个投票

You could try this:
% Prior to here, use your same code to get BW. Then...
labeledImage = bwlabeln(BW);
s = regionprops(labeledImage,'Area');
allAreas = [s.Area];
% Do the size filtering.
keeperIndexes = find(allAreas <= 500); % These are the ones that we want!
filteredLabeledImage = ismember(labeledImage, keeperIndexes);
% Apply a variety of pseudo-colors to the remaining regions and display them
coloredLabelsImage = label2rgb (filteredLabeledImage , 'hsv', 'k', 'shuffle');
% Display the pseudo-colored image.
imshow(coloredLabelsImage);
% Now measure again on the new labeled image to get areas
% of only those blobs > 50 and <= 500 pixels in area.
s = regionprops(filteredLabeledImage,'Area');
allAreas = [s.Area];

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