Stretch the middle of image

Suppose I have a .png

How can I use Matlab to stretch the middle third of the image in horizontal direction by a factor of 2?

img = imread('dough.png');%Open the image input
image(img)
 [rows,columns,~] = size(img)
 

Thank you for your help!!!

Answer 1

[KSSV]

img = imread('dough.png');%Open the image input
image(img)
 [rows,columns,~] = size(img)
 iwant = imresize(img,[2*rows columns]) ; 

[Fat Man]

Thank you for replying

But, the rows represents the Y-axis in Matlab figure. Please take a look at the output image that I would like to get

[KSSV]

The code just resizes the matrix..you will not get the effect you want as shown.

Answer 2

[DGM]

You could do this literally as the question describes

inpict = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/226538/dough.png');
[h,w,~] = size(inpict);

% split the image
w3 = round(w/3);
L = inpict(:,1:w3,:);
M = inpict(:,w3+1:2*w3,:);
R = inpict(:,2*w3+1:end,:);

% resize the middle bit, concatenate
M = imresize(M,[h 2*w3]);
outpict = [L M R];

imshow(outpict)

Or you could perhaps ease the transitions by interpolating. Here, the query curve xqn has slope 1 at its ends and slope 1/2 in the middle, but the transitions are eased in a PWL manner.

inpict = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/226538/dough.png');
[h,wi,c,~] = size(inpict);

% set up the query vector for the interpolation
wo = wi*4/3;
xout = rescale([0 0.246 0.329 0.671 0.754 1],1,wo);
xin = rescale([0 0.328 0.403 0.597 0.672 1],1,wi);
xqn = interp1(xout,xin,1:wo);

plot(xqn)
xlabel('output x-coordinates')
ylabel('input x-coordinates')

% do the interpolation
inpict = im2double(inpict);
outpict = zeros(h,wo,c);
for cx = 1:c
    outpict(:,:,cx) = interp2(inpict(:,:,cx),xqn,(1:h)');
end

imshow(outpict)

I'm sure you could also use the PWL image transformation tools and imwarp() as well. Feel free to figure that out.