MATLAB: Creating approximation line between objects.

creating lineimage processingImage Processing Toolbox

Hello, I have image with a few objects I measured centroids of each one, now I want to create approximation line using centroids. Do you have any ideas how could I do that? Thank you in advance.

Best Answer

Compute the centroids with regionprops(). Then pass those into polyfit(). Then use polyval() to get coordinates along the line.

Related Solutions

MATLAB: Regionprops didn’t work

Try this

grayImage = imread('nameimg.png');
% Get the dimensions of the image.  
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
  % It's not really gray scale like we expected - it's color.
  % Use weighted sum of ALL channels to create a gray scale image.
  grayImage = rgb2gray(grayImage); 
  % ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
  % which in a typical snapshot will be the least noisy channel.
  % grayImage = grayImage(:, :, 2); % Take green channel.
end
% Display the image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');
binaryImage = im2bw(grayImage);
[labeledImage, numBlobs] = bwlabel(grayImage);
props = regionprops(labeledImage,'Centroid')
allCentroids = [props.Centroid];
xCentroids = allCentroids(1:2:end);
yCentroids = allCentroids(2:2:end);

See my tutorial for a full demo: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

MATLAB: How to code image types

Try this:

grayImage = imread(fullFileName);
% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
	% It's not really gray scale like we expected - it's color.
	% Use weighted sum of ALL channels to create a gray scale image.
% 	grayImage = rgb2gray(grayImage);
	% ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
	% which in a typical snapshot will be the least noisy channel.
	grayImage = grayImage(:, :, 1); % Take red channel.
end
if max(grayImage(:)) == 1 && length(unique(grayImage(:))) == 2
    % It's binary because it has only two values: 0 and 1
else
    % It's grayscale
end

You can also use isa(grayImage, 'logical') or similar to identify what class it is.

Best Answer

Related Solutions

MATLAB: Regionprops didn’t work

MATLAB: How to code image types

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