Saving Pcolor/ImageSC as vector graphics with editable colors

Hello!

I am trying to output either a pcolor or imagesc plot as vector graphics, so that I can retroactively change the colors used. However, whenever I output either, the colors themselves come out as one large image (non-vector graphics) that can not be edited easily, rather than many small reactangles as I would have expected from a vector graphics output. In the case of pcolor specifically, the grid is made with vector graphics, but the colors are an independent layer that is one large image. When I place the output PDF into a program such as Adobe Illustrator, I am unable to edit the colors of the file as I would with a typical vector graphics output such as a "scatter" or "plot" figure.

Any help with this would be greatly appreciated!

I have listed a piece of example code generating and saving such plots below:

Count=50;
x=linspace(1,Count,Count);
y=linspace(1,Count,Count);
z=rand(Count);
mymap = [1 0 0; 0 1 0; 0 0 1; 0 0 0];

figure(1)
set(gcf,'renderer','painters');
colormap(mymap)
imagesc(x,y,z)
set(gca,'YDir','normal')

filepath = uigetdir(matlabroot,'Save Plot Location');
fullFilePathPDF=string(filepath)+'\TestPlot1.pdf';
exportgraphics(gcf,fullFilePathPDF,'ContentType','vector')

figure(2)
set(gcf,'renderer','painters');
colormap(mymap)
pcolor(z)

filepath = uigetdir(matlabroot,'Save Plot Location');
fullFilePathPDF=string(filepath)+'\TestPlot2.pdf';
exportgraphics(gcf,fullFilePathPDF,'ContentType','vector')

Answer 1

[Abhinav Aravindan]

Hi Daniel

I understand that you are trying to export “pcolor” and “imagesc” plots as Vector Graphics file but facing trouble in doing so. As a workaround, you may try plotting each matrix value separately using “rectangle” and export it using “print” as follows:

% Parameters 
Count = 10; 
x = linspace(1, Count, Count); 
y = linspace(1, Count, Count); 
z = rand(Count);  
mymap = [1 0 0; 0 1 0; 0 0 1; 0 0 0]; % Red, Green, Blue, Black 
 
% Create a figure 
figure; 
hold on; 
colormap(mymap); 
 
% Get the number of colors in the colormap 
numColors = size(mymap, 1); 
 
% Determine the range of the matrix 
minVal = min(z(:)); 
maxVal = max(z(:)); 
 
% Loop through each element of the matrix and draw a rectangle 
for i = 1:Count 
    for j = 1:Count 
        % Define color based on matrix value 
        colorIndex = round((z(i, j) - minVal) / (maxVal - minVal) * (numColors - 1)) + 1; 
        colorIndex = min(max(colorIndex, 1), numColors);  
        color = mymap(colorIndex, :); 
         
        % Draw rectangle with the specified color 
        rectangle('Position', [j-1, i-1, 1, 1], 'FaceColor', color, 'EdgeColor', 'none'); 
    end 
end 
 
% Set axis properties 
axis equal; 
axis tight; 
axis off; 
set(gca, 'YDir', 'reverse'); 
 
% Save the figure as a vector graphics file  
print('-vector','-dsvg','TestPlot') 

Please find below the relevant documentation:

https://www.mathworks.com/help/matlab/ref/rectangle.html

https://www.mathworks.com/help/matlab/ref/print.html

I hope this helps resolve your issue!

[DANIEL]

That works perfectly! Thank you so much for the suggestion!