# imresize3 function in older version of matlab

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Jakub on 16 Nov 2017
Commented: Walter Roberson on 24 Apr 2020
Hello, I'm using matlab R2016a version and I need to use imresize3 function. Is there any place where can I download this function, or any alternative of this function I can use in my version of Matlab? I just need to fit 168*168*135 PET image to 512*512*448 CT image. Thanx for help

Rik on 16 Nov 2017
Edited: Rik on 16 Nov 2017
Edit (sorry, too quick): Nope. As you can see in the doc for R2017b, it was introduced in R2017a.
This thread is from before the introduction of this function, so that might help you find a solution for older releases. I took the liberty of copying one of the answers below. It uses functions that aren't in the Matlab base, so you'll need the image processing toolbox (I'm assuming that isn't a problem, as imresize3 is as well, unlike imresize).
T = maketform('affine',[x_scale 0 0; 0 y_scale 0; 0 0 z_scale; 0 0 0;]);
R = makeresampler({'cubic','cubic','cubic'},'fill');
ImageScaled = tformarray(Image,T,R,[1 2 3],[1 2 3], round(size(Image)*x),[],0);
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Walter Roberson on 24 Apr 2020
x is x_scale, sort of. The original example at https://stackoverflow.com/questions/12520152/resizing-3d-matrix-image-in-matlab was only for scaling by a constant ratio in each dimension. For different ratios in each dimension you would want
T = maketform('affine',[x_scale 0 0; 0 y_scale 0; 0 0 z_scale; 0 0 0;]);
R = makeresampler({'cubic','cubic','cubic'},'fill');
ImageScaled = tformarray(Image,T,R,[1 2 3],[1 2 3], round(size(Image).*[x_scale, y_scale, z_scale]),[],0);