How to change image shape in form of V?

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Filters, such as fisheye filter can shape the image with fisheye distortion. Is there a filter in which the image can look squeezed from bottom and wide from top? Such as a V?

Accepted Answer

Guillaume
Guillaume on 6 Apr 2017
Use imwarp with a projective2d transform:
I = checkerboard(40);
transform = fitgeotrans([1, 1; size(I, 2), 1; 1, size(I, 1); size(I)], ...
[1, 1; size(I, 2), 1; 100, size(I, 1); size(I, 2)-100, size(I, 1)], ...
'projective');
imshowpair(I, imwarp(I, transform), 'montage')
  5 Comments
h612
h612 on 6 Apr 2017
I'm attaching the result. The black region can be seen in the result. I am wondering how can I not have that region 0- infact some interpolation of the neighbouring pixels
Guillaume
Guillaume on 6 Apr 2017
I still have no idea what you want to interpolate in the black region. There is nothing there to interpolate. If you want to smear the edge of the image, you can use the older tformarray with a resampler that 'replicate' values.
transform = maketform('projective', ...
[1, 1; size(I, 2), 1; 1, size(I, 1); size(I)], ...
[1, 1; size(I, 2), 1; 100, size(I, 1); size(I, 2)-100, size(I, 1)]);
resampler = makeresampler('cubic', 'replicate');
imshowpair(I, tformarray(I, transform, resampler, [2 1], [2 1], [], []), 'montage');
However, note that most of these functions are deprecated. I don't know how to do the same with the new imwarp.

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