Correct image barrel or pincushion distortion, or apply these to non-distorted images. This function is a modified version of that written by Jaap de Vries on the File Exchange. The present code has been modified in the following ways:

• Default interpolation is set to linear.
• The padding value defaults to image minimum and can be modified via an input argument.
• It's possible to set a different value of k for rows and columns (see example below).
• An image stack can be supplied and this is processesed more efficiently by feeding the whole stack as an input to tformarray.
• Affine transformation along with distortion correction.

c=checkerboard(25,30);
inputIm = c(:,:,1)*2^8;
 
figure
subplot(2,2,1), imagesc(inputIm), title('orig')
subplot(2,2,2), imagesc(lensdistort(inputIm, 0.2)), title('barrel')
subplot(2,2,3), imagesc(lensdistort(inputIm, -0.2)), title('pincushion')
subplot(2,2,4), imagesc(lensdistort(inputIm,[-0.2,0.4])), title('both')