MATLAB: How can specific positions in the below image

image processingImage Processing Toolboximage segmentation

Hello Friends.

I am looking for to find the positions(i,j) of light green boundaries in the below images.

A needed m.file for loading the required data is attached. In the below code, etas and eta are matrix with predefined size.

%code
load Etas
Nx=128;
eta2=zeros(Nx,Nx);
ncount=0;
%original code
for igrain=1:25
    
    ncount=0;
    for i=1:Nx
        for j=1:Nx
            ii =(i-1)*Nx+j;
            
            eta2(i,j) =eta2(i,j)+etas(ii,igrain)^2;
            if(etas(ii,igrain) >= 0.5)
                ncount=ncount+1;
            end
%             
            ncount=ncount/(Nx*Nx);
        end
        
    end
end
%Display
figure
imagesc(eta2)

Best Answer

Threshold eta2 then skeletonize to get single pixel wide lines. Then call find to get the rows and columns of every white pixel.

binaryImage = bwmorph(eta2 < 0.6, 'skel', inf);
[rows, columns] = find(binaryImage);

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MATLAB: How can set colormap for below matirx

I think this is what you want:

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;
% Existing code
Nx=64;
Ny=Nx;
eta2 = zeros(64,64);
% original code
load storeEtas
for igrain=1:25
	ncount=0;
	for i=1:Nx
		for j=1:Nx
			ii =(i-1)*Nx+j;
			eta2(i,j) =eta2(i,j)+etas(ii,igrain)^2;
			if(etas(ii,igrain) >= 0.5)
				ncount=ncount+1;
			end
			ncount=ncount/(Nx*Ny);
		end
	end
end
figure
% New code below by Image Analyst:
subplot(2, 3, 1);
imshow(eta2, [], 'ColorMap', hsv(256));
colorbar;
title('eta2, Pseudo-colored', 'FontSize', fontSize);
impixelinfo;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
drawnow;
% Plot the image in gray scale
subplot(2, 3, 2);
imshow(eta2, [], 'ColorMap', gray(256));
colorbar;
title('eta2, Actual values (gray scale)', 'FontSize', fontSize);
impixelinfo;
% Show the histogram
subplot(2, 3, [3, 6]);
imhist(eta2);
grid on;
title('Histogram of eta2', 'FontSize', fontSize);
% Threshold the image
thresholdValue = 0.7;
line([thresholdValue, thresholdValue], ylim, 'Color', 'r', 'LineWidth', 2);
binaryImage = eta2 > thresholdValue;
subplot(2, 3, 4);
imshow(binaryImage);
title('Binary Image', 'FontSize', fontSize);
% Label the image so we can assign (almost) unique colors to each region,
% and so we can make measurements of it, such as the area of each blob.
[labeledImage, numberOfBlobs] = bwlabel(binaryImage, 8);
fprintf('Found %d blobs.\n', numberOfBlobs);
% Apply a variety of pseudo-colors to the regions.
coloredLabelsImage = label2rgb (labeledImage, 'hsv', 'k', 'shuffle');
% Display the pseudo-colored image.
subplot(2, 3, 5);
imshow(coloredLabelsImage);
title('Individually colored regions of eta2', 'FontSize', fontSize);
% Get all the blob properties.
blobMeasurements = regionprops(labeledImage, eta2, 'all')
% blobMeasurements is an array of structures.  Each structure has a bunch of measurements in it.
% For example, get all the areas into a single vector.
allAreas = [blobMeasurements.Area]

MATLAB: Histogram thresholding to get the threshold point

I can't understand any rationale for that algorithm. What do you think thresholding the difference of the histograms will get you? What do you even think the difference of the histograms represents? Where did you come up with such an algorithm?

Where did you upload your image?

Best Answer

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