Expanding a matrix using interpolation?

Hi everyone,

I have a 7X5 matrix called "Temperatures", and I was wondering if I could interpolate these values it both directions to get a better 2D temperature gradient graph?

This are the values in my matrix:

And using ">> imagesc(Temperatures)" I get something like this

Is it possible to interpolate this matrix to obtain a better temperature gradient graph?

Thank you!

Answer 1

[John D'Errico]

Simplest is to use imresize. I assume it used to be in the image processing TB, but has migrated to MATLAB itself, due to the general utility of that function.

T = [     300          300          300          300          300
          300        346.3        358.9        346.3          300
          300        363.8        380.5        363.8          300
          300        356.8        373.2        356.8          300
          300        363.8        380.5        363.8          300
          300        346.3        358.9        346.3          300
          300          300          300          300          300];

Tnew = imresize(T,30,'bilinear');
pcolor(Tnew)
shading interp

Given the coarse starting array, it does not merit more that that. Be careful with the bicubic option with imresize here.

Another option is to use interp2.

Tnew = interp2(T,5,'bicubic');
surf(Tnew)
shading interp

To be honest, your array may be far too coarse to merit that treatment.

[Claudio Duarte Silva]

Thank you very much! :)

Answer 2

[Ameer Hamza]

Use interp2(), as follow

newNumberOfRows = 10;  % set the number of rows interpolated rows you want
newNumberOfCols = 5;   % set the number of columns interpolated rows you want
[x, y] = meshgrid(1:size(A,2), 1:size(A,1));
[xq, yq] = meshgrid(linspace(1, size(A, 2), newNumberOfCols), linspace(1, size(A, 1), newNumberOfRows));
newMatrix = interp2(x, y, A, xq, yq)

[Claudio Duarte Silva]

Thank you!