You can specify the ColorLimits of all three heatmaps after they are created.
Here's a demonstration with some random data:
for compo = 1:3
subplot(1,3,compo)
% 1st heatmap ranges between 1 and 2, 2nd is [2 3], 3rd is [3 4]
% in order to see the effect of using common ColorLimits
this_spec = compo+rand(5,10);
hdl(compo) = heatmap(1:5,1:10,this_spec');
end
if numel(hdl) > 1
c_lim = get(hdl,'ColorLimits');
c_lim = vertcat(c_lim{:});
c_lim = [min(c_lim(:,1)) max(c_lim(:,2))];
set(hdl,'ColorLimits',c_lim);
end
