How can I resample an image in matlab?

Hello

I want to resample an image in matlab. I use imresample code of by Omer Demirkaya. but I have bellow error.

• | |Error using griddedInterpolantSample values must be a single or double array.

Error in interp2/makegriddedinterp (line 214) F = griddedInterpolant(varargin{:});

Error in interp2 (line 135) F = makegriddedinterp(X, Y, V, method,extrap);

Error in imresample (line 49) nimg(:,:,i) = interp2(Ox,Oy,img(:,:,i),Nx,Ny,intmethod);| | *

Could you help me how can I resample an image?

Thanks for your help.

Answer 1

[Walter Roberson]

Before you start the interpolation, do

img = im2double(img);

[bkshn]

Hello Walter Roberson

Thanks for your answer I have another question, Could you answer me, I'll appreciate your help. I do resampling and done an algorithm on my Image, right now I want to return resampled image to first image(I want to undo resampling), what can I d0? I resample my image by this

NI = imresample([0.2,0.2],I,[1,1],'linear');

I want to undo resampling by this

NI2 = imresample([1,1],NI,[0.2,0.2],'linear');

but It didn't work!

[Walter Roberson]

What happens instead of it "working" ?

[bkshn]

I found my answer thanks alot for your help

Answer 2

[Image Analyst]

Why not simply use imresize()?

Answer 3

[Alex Taylor]

The MATLAB interpolation functions require that the inputs be floating point, since interpolation is a floating point operation. Walter's comment is accurate, if you want to interpolate in double precision floating point, im2double will work.

To Image Analyst's point: are you trying to apply a geometric transformation like scaling, rotating, or a generic affine transformation to an image? If so, it would be easier to look at imresize, imrotate, or imwarp if you have the Image Processing Toolbox. These will take care of the resampling for you.