Image rotation and NaN elements
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The following code rotates an image by a given angle θ. I do not understand the function and significance of the last line:
n = size(Image,1);
x = linspace(-1,1,n);
[X1,Y1] = meshgrid(x,x);
% Coordinate rotation
X = cos(theta)*X1 + -sin(theta)*Y1;
Y = sin(theta)*X1 + cos(theta)*Y1;
RotatedImage = interp2(X1,Y1,Image,X,Y);
RotatedImage(isnan(RotatedImage)) = 0;
If I understand correctly, it eliminates the elements in the final image that are NaN. But why would the rotation or interpolation introduce elements which are not-a-number?
When I omit this line, the resulting image looks nothing like the original image. Without this line, is there any alternative way of avoiding NaN elements?
Any explanation would be appreciated.