Storing numeric data in images makes it difficult to work with those data later on but I remember a use-case for this back when I wanted to quickly snap-shot small data sets for visual reference (still not sure it was the best approach).
Nevertheless, if your matrix fits on a single page, you could put the data in a uitable and then extract the figure using exportapp. Note that precision may be lost since there is a finite number of decimal places that will appear on the table. See uitable documentation to learn how to apply column and row labels.
x = rand(10,5)*100;
fig = uifigure(); % must be uifigure
uit = uitable(fig,'Units','Normalize','Position',[0 0 1 1],'Data', x)
After the figure and uitable are rendered, you can export the figure as an image using exportapp.
% drawnow % only needed if calling exportapp immediately after uitable.
% pause(.5) % only needed if calling exportapp immediately after uitable.
exportapp(fig, 'mytable.png')
