how measure major and minor axis of ellipse from image used matlab

see a picture

[darova]

What have you tried? Do you have any ideas?

[Image Analyst]

[darova]

It's not enough for helping you

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 22;
% Check that user has the Image Processing Toolbox installed.
hasIPT = license('test', 'image_toolbox');
if ~hasIPT
  % User does not have the toolbox installed.
  message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');
  reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
  if strcmpi(reply, 'No')
    % User said No, so exit.
    return;
  end
end
%===============================================================================
% Read in a color demo image.
folder = pwd;
baseFileName = '6.bmp';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % 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.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(grayImage);
if numberOfColorBands > 1
	fprintf('This image is RGB.  I will change it to gray scale.\n');
	grayImage = grayImage(:, :, 2);
end
% Display the original image.
subplot(2, 2, 1);
imshow(grayImage);
axis('on', 'image');
title('Green Channel Image', 'FontSize', fontSize);
impixelinfo;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0.1, 1, 0.9]);

subplot(2, 2, 2);
imhist(grayImage);
grid on;
title('Intensity Histogram', 'FontSize', fontSize);

% It's gray scale.  Threshold to create a binary image.
binaryImage = grayImage < 90; % or whatever value works.

subplot(2, 2, 3);
imshow(binaryImage, []);
axis('on', 'image');
title('Binary Image', 'FontSize', fontSize);

% Get rid of partial blobs leaving the field of view.
binaryImage = imclearborder(binaryImage);

% Get rid of blobs less than 500 in area.
binaryImage = bwareaopen(binaryImage, 500);

binaryImage = imfill(binaryImage, 'holes');
[labeledImage, numberOfblobs] = bwlabel(binaryImage);
% Apply a variety of pseudo-colors to the regions.
coloredLabelsImage = label2rgb (labeledImage, 'hsv', 'k', 'shuffle');
% Display the pseudo-colored image.
subplot(2, 2, 4);
imshow(coloredLabelsImage);
axis('on', 'image');
title('Filled Binary Image', 'FontSize', fontSize);

% Make measurements of area.
props = regionprops(binaryImage, 'Area', 'MajorAxisLength', 'MinorAxisLength')
allAreas = [props.Area]
majorAxisLength = [props.MajorAxisLength]
minorAxisLength = [props.MinorAxisLength]

msgbox('Done!  lengths are in the command window.');

allAreas =

901 869 895 828 938 950 897 982 893 849 876

majorAxisLength =

Columns 1 through 5

42.3096288162948 41.4884349273287 42.8162935858843 41.2903546123474 42.7337289342248

Columns 6 through 10

44.1105808446811 42.0295867943025 38.2652632328308 42.4311889315166 41.8919530940952

Column 11

38.6585845668433

minorAxisLength =

Columns 1 through 5

27.4939460477342 27.0457380137077 27.0387459149836 26.0994881281772 28.1097891482489

Columns 6 through 10

27.8269540727149 27.5096530490088 32.7371049402545 27.2963558415452 26.2322961767191

Column 11

28.9929460861065

[Mushtaq Al-Jubbori]

thank you very mach

did help me

print valuse of mainor and major axis on every track of origin image

[Image Analyst]

Replace the last chunk of code with this:

% Make measurements of area.
props = regionprops(binaryImage, 'Area', 'Centroid', 'MajorAxisLength', 'MinorAxisLength')
allAreas = [props.Area]
majorAxisLength = [props.MajorAxisLength]
minorAxisLength = [props.MinorAxisLength]
% Display centroids over image.
figure
imshow(grayImage);
axis('on', 'image');
impixelinfo;
hold on;
centroids = vertcat(props.Centroid);
for k = 1 : length(props)
	x = props(k).Centroid(1);
	y = props(k).Centroid(2);
	plot(x, y, 'r+', 'LineWidth', 2, 'MarkerSize', 20);
	str = sprintf('  (%.1f, %.1f)', x, y);
	text(x, y, str, 'Color', 'r', 'FontSize', 20, 'FontWeight', 'bold');
end
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
msgbox('Done!  lengths are in the command window.');

[Mushtaq Al-Jubbori]

Please, why there are differences between the values on the picture and values in the workspace?

Please, why does the program not measure minor and major axes on these atached pictures?

[Image Analyst]

In the workspace there will be more significant digits. I chose only to show 2 on the image since that seemed plenty.

For other images, you may need to adjust the threshold. See my File Exchange for a manual/interactive app that lets you visually select the threshold interactively. If changing the threshold doesn't work, try to see what is different between the two, like the focus or contrast or something.

[Mushtaq Al-Jubbori]

I'm grateful to you for helping me

[Mushtaq Al-Jubbori]

Is it possible to isolate the tail and measure separately؟

[Image Analyst]

What is the head and tail? Is it the two ends of the ellipse? What do you want to measure on them? And most importantly: WHY? Is it possible to measure something that is simpler and gives you basically the same, or correlated, information, like eccentricity or aspect ratio or something. If you really need to measure the different radii of curvatures for each end of the blob, it can be tricky. Basically you'd have to get the outer boundary coordinates, then split the blob apart in to two somehow (like halfway along the major Feret distance), then get the two outlines. Then extract only those outline points that are in the original outline so you won't get the dividing line where you split it. Then fit that to a circle using code in the FAQ.

[Mushtaq Al-Jubbori]

Thank you for your answer, see attach image I want measure tial and track Separate

I need to measure all upove Which you mentioned

[Image Analyst]

OK. I'd try to find the orientation and centroid and split the blob in half. First I'd get the boundary of the blob before it's been split using bwboundaries(). Then I'd get the boundary of each half and get those coordinates that are not in the interior, in other words get the values that are just on the outer perimeter. Can probably use ismember() for that. Then fit each half to a circle using the code from the FAQ, Good luck.

[Mushtaq Al-Jubbori]

Did can add another dimention add to mainor and major axises for elips?

[Image Analyst]

I have no idea what this means. Do you have a 3-D image? A volumetric image, like from confocal microscopy of something? If so, there is a regionprops3() function that deals with 3-D.

[Mushtaq Al-Jubbori]

Yes, I mean a 3 -D image but I don't have

The track have minor , major and length axis

[Mushtaq Al-Jubbori]

If possible, delete the tail, and measure the mainor and major axis of the track, and add the length of the track, so that did we can draw the diameter of the track in 3 dimensions

[Image Analyst]

I think what you want requires an amount of time and effort that goes way beyond what time I can donate to you. I usually don't donate more than 10 or 15 minutes to a small solution. Tracking is very difficult and I don't have such a program, though I'm sure you can buy one. Tracking in three dimensions is even harder. Also I don't know why you need to chop off the tail. Why would that have any significant effect on the track/path that the blob travels? What is the REAL thing you want to measure? I mean maybe you're saying delete the tail just because you think you need to, but really you don't need to and would have no effect on the real thing you want to measure. Plus if the actual tracking algorithm is a part of your dissertation, then I can't do it for you - you'd need to do it so you can claim it as yours, right?

[Mushtaq Al-Jubbori]

No, you helpe me already, but I want to delete the tail and measure the axes so that I can determine the energy

This M-file not applied on my image

https://www.mathworks.com/matlabcentral/answers/425498-how-to-detect-ellipse-in-the-picture?s_tid=srchtitle

[Image Analyst]

So is the energy correlated with whether it has a substantial tail, or how fast the blob travels from frame to frame? And assuming you could measure various metrics about the shape, what is the equation for energy base on those metrics, like

energy = headRadiusOfCurvature - 10*tailRadiusOfCurvature + 4*feretDiameter + 189 * circularity; % or whatever.

[Mushtaq Al-Jubbori]

Thank you very much, I whish to help me , complete the program and applied on my image