How to improve my contour plot sensitivity?

Hi,

I'm creating contour/heat maps from data from excel. I am currently using this code (found this online, but cannot remember who to cite - sorry!):

%Import the data in from excel
num = xlsread('DATA.xlsx')

% Reshape the intensity vector into a matrix
[xUnq,~,xIdx] = unique(num(:,1)); 
[yUnq,~,yIdx] = unique(num(:,2)); 
zMat = nan(numel(yUnq),numel(xUnq)); 
zIdx = sub2ind(size(zMat),yIdx,xIdx);
zMat(zIdx) = num(:,3);
% Plot contour
contourf(xUnq,yUnq,zMat)
% Label colour bar
c = colorbar;
c.Label.String = 'CL_{004} (nm)';

This produces a map like this:

However, I'm not finding the sensitivity is quite right, as there large regions of red, where the values all vary. Is there a way to improve this so the variation is more visible?

Additionally, is there a way to remove the black lines around each region?

Thanks in advance!

Answer 1

[KSSV]

Try:

pcolor(xUnq,yUnq,zMat)
shading interp
colorbar

[Sam]

Thank you so, so much!