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Cylindrical projection from image normal coordinates

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Preetham Manjunatha
Preetham Manjunatha on 1 Aug 2021
I am trying to project normal image coordinates to cylindrical projection using the MATLAB's
imwrap
function. But the output image is terrible.
fileName = 'peppers.png';
image = imread(fileName);
f = 200;
[h, w, bypixs] = size(image);
K = [f,0,w/2; 0,f,h/2; 0,0,1];
x = 1:w;
y = 1:h;
[X,Y] = meshgrid(x,y);
X = X';
Y = Y';
XYZ = [X(:) Y(:) ones(h*w,1)];
XYZnew = (K \ XYZ')';
A = [sin(XYZnew(:,1)), XYZnew(:,2), cos(XYZnew(:,1))];
B = (K * A')';
% back from homog coords
B = B(:,1:2) ./ B(:,3);
% Make sure warp coords only within image bounds
B((B(:,1) < 0) | (B(:,1) >= w) | (B(:,2) < 0) | (B(:,2) >= h),:) = -1;
B = pagetranspose(reshape(B, w, h, 2));
% Image warp
Icy = imwarp(image, B, 'FillValues', [0 0 0]);
% Display warped image
figure;
subplot(1,2,1); imshow(image)
subplot(1,2,2); imshow(Icy)
Below is the output image:
Any inputs to solve this issue is much appreciated!
  2 Comments
Preetham Manjunatha
Preetham Manjunatha on 1 Aug 2021
It should look like this:
Above image has transparent background, in my case it is black. Cylindrical projection is a mapping from the Cartesion (or any) to Cylindrical coordinates. Here I am trying to warp the given normal/regular image to Cylindrical coordinates to get better panaroma stitching.

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