Image Transformation to Polar

Question

Stefan Ungurea 2020-2-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/504435-image-transformation-to-polar

回答： Puru Kathuria 2021-3-14

I'm essentially trying to transform an image from cartesian to polar. My script works for an empty grid(i used this to test my function) but the output isnt exactly what I want for the image. I cannot figure out what went wrong in my function. So my grid is supposed to do this:

And that works fine, but my image goes from this:

to this:

The chin and teeth get cut out of the image. A quick note, I want to write my own transformation and do not want to use cart2pol or poltocart. I just cannot see where I went wrong in my function(below). The function takes the image as input, an angle of rotation, and a center of which to rotate about. In this case theta = 90 and xc = yc =1. Any thoughts?

function RotateImage = RotateImage(mat,theta, xc, yc)
   %Define rotation coordinates
   [rY, rX] = meshgrid(0:size(mat,1)-1, 0:size(mat,2)-1); % define the necessary rotation matrix locations in X and Y
   y_max = max(max(rY));
   %%%%%  transform from polar to cartesian %%%%%
   
   %Assuming rX maps to the radius and rY maps to the angle
   
   %ShiftX = rX; %shift center for x
   ShiftY = y_max/rY * theta; %shift center for y
   
   X = rX .* cosd(ShiftY); %convert back to cartesian
   Y = rX .* sind(ShiftY);
   
   originalX = X+xc; %shift back to center
   originalY = Y+yc;
   
   IR = interpolate(mat,originalX,originalY); %interpolate
   RotateImage = IR; 
end