How to set x-ticks and y-ticks for the Raman image?

I would like to set x-ticks and y-ticks labels for my Raman Intensity Ratio image. My data consists of Raman intensity ratio for each coordinate of X axis and Y- axis.

The Raman intensity ratio data was collected in step size of 20µm. The X-axis starts from -195 µm till 204µm. The Y-axis -122µm to 137µm. I have attached an image of the result. I am not able to see the xticks and y-ticks on the image.

Also would it be possible to get the coordinate value from the image? I am intrested in the coordinate which are red in color. This would help me to get a Raman Intensity vs Wavenumber for a particular coordiante.

clear all
clear vars
%Loading data
Raman_Ratio=readtable("Raman Intensity Ratio.xlsx");
%Define variables
X_start=Raman_Ratio{1,"X_coordinate"};
X_end=Raman_Ratio{end,"X_coordinate"};
Y_start=Raman_Ratio{:,"Y_coordinate"};
Y_end=Raman_Ratio{end,'Y_coordinate'};
X_cord=Raman_Ratio{:,"X_coordinate"};
Y_cord=Raman_Ratio{:,"Y_coordinate"};
RI=Raman_Ratio{:,"IntensityRatio"};
% Grid of coordinates for above data
xi=X_start:20:X_end;
yi=Y_start:20:Y_end;
[X,Y]=meshgrid(xi,yi);
% For finer grid of points
m_2=X_start:1:X_end;
n_2=Y_start:1:Y_end;
[X2,Y2]=meshgrid(m_2,n_2);
%Interpolating the values of Raman Ratio into the grid
Z=griddata(X_cord,Y_cord,RI,X2,Y2);
%Showing the data as image
imshow(Z)
colormap("jet")
%adding xticks and xlabels
xticks([X_start 20 X_end])
xticklabels('auto')
%Defining a colorbar
c1=colorbar;
c1.Label.String='Raman Intensity Ratio';
caxis([0.5 0.8])

Answer 1

[Star Strider]

Try this —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/887625/Raman%20Intensity%20Ratio.xlsx', 'VariableNamingRule','preserve')

T1 = 294×3 table
    X-coordinate    Y-coordinate    Intensity Ratio
    ____________    ____________    _______________

      -195.29         -122.38           0.67591    
      -175.29         -122.38           0.65792    
      -155.29         -122.38            0.6517    
      -135.29         -122.38           0.67788    
      -115.29         -122.38           0.65057    
      -95.289         -122.38            0.6676    
      -75.289         -122.38            0.6626    
      -55.289         -122.38           0.61923    
      -35.289         -122.38           0.66892    
      -15.289         -122.38           0.63612    
       4.7108         -122.38           0.65157    
       24.711         -122.38           0.62615    
       44.711         -122.38           0.63971    
       64.711         -122.38           0.65806    
       84.711         -122.38           0.65193    
       104.71         -122.38           0.63174    

[Uy,ia] = unique(T1.('Y-coordinate'));
Udia = unique(diff(ia))

Udia = 21

Xm = reshape(T1.('X-coordinate'), Udia, []);
Ym = reshape(T1.('Y-coordinate'), Udia, []);
Zm = reshape(T1.('Intensity Ratio'), Udia, []);

figure
surfc(Xm, Ym, Zm)
grid on
shading('interp')
colormap(turbo)
c1=colorbar;
c1.Label.String='Raman Intensity Ratio';
xlabel('X')
ylabel('Y')
zlabel('Intensity Ratio')
view(0,90)
axis('equal')                                                   % Optional

The data are gridded, so it is necessary to reshpae them to matrices. That is straightforward once the details of the grid are known (privided by ‘Udia’ here).

Using imshow flips the y-axis, because that is the coordinate convention for images.

The surf plot shows the correct orientation and coordinates.

.

[Anshul Choubey]

Thank you so much for your time and the answer. This worked out very well.

[Star Strider]

As always, my pleasure!