how to re-find the landmark locations after imcrop !!

In my gray scale image, I have a set of landmark points that i know their positions(xi,yi). I calculate my rectangular region then i use imcrop to extract the ROI from the original image then I use imresize to [120*120]. The problem is that I need again the locations of my Landmark for further treatment.After these transformation(imcrop-imresize) I can not understand how to find their new coordinatess!!? Any Help Please......

[Brattv]

Hi, it would be easier to help if you provide the code you have written.

Answer 1

[Image Analyst]

First subtract the leftX and topY from the x and y values you have, then multiply them by the scaling factors you used in the resize.

[Omokhadija]

This is my code:

[I, rect]=imcrop(Image); %%top left point x1=rect(1); y1=rect(2); %%Height+Width x2=rect(1)+rect(3); y2=rect(2)+rect(4); [A]=imresize(I,[96 96],'bilinear'); %%List of Landmarks point L=[305 264;343 263;327 280;326 302]; %%Translation T=[ rect(1) rect(2)]; %%Sclae sc1=96/rect(3); sc2=96/rect(4);

XXL=[]; for i=1:size(L,1) XXL(i,:)=L(i,:)-T; XXL(i,1)=sc1*XXL(i,1); XXL(i,2)=sc2*XXL(i,2); end

figure(5), imshow(A);hold on, plot( XXL(:,1),XXL(:,2) ,'r.','markersize',15);

When i plot the new points they didn't match with the supposed locations ...I think i have some error when applying sclae!!Can youhelp please!!

[Image Analyst]

Sorry - I can't read it. Read this: http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

Answer 2

[Omokhadija]

This is my code:

[I, rect]=imcrop(Image); %%top left point x1=rect(1); y1=rect(2); %%Height+Width x2=rect(1)+rect(3); y2=rect(2)+rect(4); [A]=imresize(I,[96 96],'bilinear'); %%List of Landmarks point L=[305 264;343 263;327 280;326 302]; %%Translation T=[ rect(1) rect(2)]; %%Sclae sc1=96/rect(3); sc2=96/rect(4);

XXL=[]; for i=1:size(L,1) XXL(i,:)=L(i,:)-T; XXL(i,1)=sc1*XXL(i,1); XXL(i,2)=sc2*XXL(i,2); end

figure(5), imshow(A);hold on, plot( XXL(:,1),XXL(:,2) ,'r.','markersize',15);

When i plot the new points they didn't match with the supposed locations ...I think i have some error when applying sclae!!

[Brattv]

Please copy the code to the commentary field, mark the code and then press the {}Code button

The result will be much easier to read

for i=1:end 
do something
do something 1
looks much better
end

[Omokhadija]

[I, rect]=imcrop(Image); 
%%top left point %%
x1=rect(1); y1=rect(2);
%%Height+Width %%
x2=rect(1)+rect(3); 
y2=rect(2)+rect(4); 
[A]=imresize(I,[96 96],'bilinear'); 
%%List of Landmarks point %%
L=[305 264;343 263;327 280;326 302]; 
%%Translation%%
T=[ rect(1) rect(2)]; %%Sclae sc1=96/rect(3); sc2=96/rect(4);

XXL=[]; %% for i=1:size(L,1)

XXL(i,:)=L(i,:)-T; 
XXL(i,1)=sc1*XXL(i,1);
 XXL(i,2)=sc2*XXL(i,2); end

figure(5), imshow(A);hold on, plot(XXL(:,1),XXL(:,2),'r.','markersize',15);