MATLAB: How to create an image in Matlab from .txt file

create imageimageimage processingluminosity;

I have some .txt files containing 3 columns of number (x,y,z). z is the luminosity of each point identified by the x,y coordinates. So i have 3 vectors containing 316920 elements each. I should find a way to produce an image file (the format is not important, it may be a .jpg for example) in which the luminosity (z vector) of each point whose coordinates are identified by the first 2 columns of the .txt file (x and y coordinates) vary depending on the third column (vector z). How can I concert the coordinates and luminosity into an image? Thanks!

Best Answer

data = importdata('your text file') ;
x = data(:,1) ;
y = data(:,2) ;
z = data(:,3) ;
x0 = min(x) ; x1 = max(x) ;
y0 = min(y) ; y1 = max(y) ;
N = 1000 ;  % can be varied
xi = linspace(x0,x1,N) ;
yi = linspace(y0,y1,N) ;
[X,Y] = meshgrid(xi,yi) ;
Z = griddata(x,y,z,X,Y) ;
surf(X,Y,Z) ;
view(2)
shading interp 
axis tight  
saveas(gcf,'myfile.jpg')

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MATLAB: Contour plot for given x,y,z


[num,txt,raw] = xlsread('Book1.xlsx') ; 
x = num(:,1) ; 
y = num(:,2) ; 
z = num(:,3) ; 
figure(1)
scatter(x,y,20,z,'filled') ; colorbar
%% Method 1 / Griddata
nx = 500 ; ny = 500 ;
[X,Y] = meshgrid(linspace(min(x),max(x),nx),linspace(min(y),max(y),ny)) ;
Z =griddata(x,y,z,X,Y) ;
figure(2)
contour(X,Y,Z) ;
figure(3)
pcolor(X,Y,Z)
shading interp 
%% Method 2 simple reshaping 
x = unique(x) ; nx = length(x) ;
y = unique(y) ; ny = length(y) ;
Z = reshape(z,ny,nx) ;
figure(4)
contour(x,y,Z)

MATLAB: How to convert a closed curve into a binary mask

data = importdata('data.txt') ; 
x = data(:,1) ; 
y = data(:,2) ; 
N = 500 ; 
xi = linspace(min(x),max(x),N) ; 
yi = linspace(min(y),max(y),N) ; 
[X,Y] = meshgrid(xi,yi) ; 
idx = inpolygon(X,Y,x,y) ; 
Z = ones(size(X)) ; 
Z(idx) = 0 ; 
imshow(Z)

Best Answer

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MATLAB: Contour plot for given x,y,z

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