MATLAB: Imrotate won’t work in this scenario,any other suggestions

Image Processing Toolboxrotate

I want to rotate an image at a pivot point(eg:at the center of the 1st feature, which is NOT the center of the image) without changing the size and shape of the image. I tried imrotate, but it won't work in this scenario. My intention is to stack similar features(eg:features 1 & 2) for each set.How to stack these similar features though? Your response on this regard is appreciated.

Best Answer

Chathu

there is a function in

http://uk.mathworks.com/matlabcentral/fileexchange/57492-rotate-image-around-arbitrary-point

that does the same as the following script, basically

1.- introduce rotation point

2.- 1st padarray

3.- 2nd padarray

4.- imrotate with circle showing furthest pixel radius

the script:

clc;clf;
% clear all
A=imread('countryside.jpg');
figure(1);imshow(A);
angle1=randi([1 359],1,1);
if angle<1
    disp('choose angle > 1º');B4=A;
    return; end;
% measure image size
[sy sx sz]=size(A);
% find image centre [xc yc]
xc=floor(sx/2);
yc=floor(sy/2);
% choose the point [x1 y1] to behave as Z rotation axis
[x1 y1]=ginput(1);
% visualize both [xc yc] and [x1 y1]
hold on;figure(1);plot(x1,y1,'r*','MarkerSize',10);
hold on;figure(1);plot(xc,yc,'ro','MarkerSize',10);
% make sure x1<>xc and y1<>yc
if (x1==xc)
    x1=x1+2*(randi([0 1],1,1)-.5); end;
if (y1==yc)
   y1=y1+2*(randi([0 1],1,1)-.5); end;
ks=0;
if (x1<xc & y1<yc) ks=1; end;
if (x1>xc & y1<yc) ks=2; end;
if (x1>xc & y1>yc) ks=3; end;
if (x1<xc & y1>yc) ks=4; end;
t=0:2*pi/100:2*pi;
switch ks
    case 1 % x1<xc & y1<yc
          D=norm([x1 y1]-[sx sy]);
% 1st pair of padding margins



dx=D+x1-sx;
alpha=atand((sx-x1)/(sy-y1));
s=(2*D^2-2*D^2*cosd(alpha))^.5;
dy=(s^2-(sx-x1)^2)^.5;
% dy=D+y1
dx=floor(dx);dy=floor(dy);
B=padarray(A,[dy,dx],'both');
figure(2);imshow(B);
[sby sbx sbz]=size(B);
hold on;figure(2);plot(x1+dx,y1+dy,'r*','MarkerSize',10);
hold on;figure(2);plot(xc+dx,yc+dy,'ro','MarkerSize',10);
% the origin has been displaced [-dx -dy]


% the point [x1 y1] to become rotation Z axis now has coordinates [dx+x1 +dy+y1]


% visualizing the outer rotation circle


x0d=D*cos(t); xd=x0d+dx+x1;
y0d=D*sin(t); yd=y0d+dy+y1;
hold all;figure(2);plot(xd,yd,'r','LineWidth',1.5);
% visualizing axes after 2nd padarray and origin displacement







hold all;figure(2);plot([1:1:sbx],ones(1,sbx).*(dy+y1),'w','LineWidth',1.5);  % new x axis







hold all;figure(2);plot(ones(1,sby).*(dx+x1),[1:1:sby],'w','LineWidth',1.5);  % new y axis





% calculating 2nd padarray margins



dx2=2*D-sbx;dx2=floor(dx2);
dy2=2*D-sby;dy2=floor(dy2);
B3=padarray(B,[dy2 dx2],50,'pre');
[sb3y sb3x sb3z]=size(B3);
figure(4);imshow(B3);
% visualizing initial image centre [xc yc] and and chosen rotation point [x1 y1]




hold all;figure(4);plot(x1+dx+dx2,y1+dy+dy2,'r*','MarkerSize',10);
hold all;figure(4);plot(xc+dx+dx2,yc+dy+dy2,'ro','MarkerSize',10);
% visualizing outer circle after 2nd padarray




xd2=xd+dx2;
yd2=yd+dy2;
hold all;figure(4);plot(xd2,yd2,'r','LineWidth',2.5);
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(4);plot([1:1:sb3x],ones(1,sb3x).*(dy+y1+dy2),'w','LineWidth',1.5);  % new x axis
hold all;figure(4);plot(ones(1,sb3y).*(dx+x1+dx2),[1:1:sb3y],'w','LineWidth',1.5);  % new y axis
      case 2 % x1>cx & y1<yx
     D=norm([x1 y1]-[0 sy]);
% 1st pair of padding margins
dx=D-x1;
alpha=atand((sy-y1)/(sx-x1));
s=(2*D^2-2*D^2*cosd(alpha))^.5;
dy=(s^2-(sx-x1)^2)^.5;
dy=D-y1;
dx=floor(dx);dy=floor(dy);
B=padarray(A,[dy,dx],'pre');
figure(2);imshow(B);
[sby sbx sbz]=size(B);
hold on;figure(2);plot(x1+dx,y1+dy,'r*','MarkerSize',10);
hold on;figure(2);plot(xc+dx,yc+dy,'ro','MarkerSize',10);
% the origin has been displaced [-dx -dy]
% the point [x1 y1] to become rotation Z axis now has coordinates [dx+x1 +dy+y1]
% visualizing the outer rotation circle
x0d=D*cos(t); xd=x0d+dx+x1;
y0d=D*sin(t); yd=y0d+dy+y1;
hold all;figure(2);plot(xd,yd,'r','LineWidth',1.5);
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(2);plot([1:1:sbx],ones(1,sbx).*(dy+y1),'w','LineWidth',1.5);  % new x axis
hold all;figure(2);plot(ones(1,sby).*(dx+x1),[1:1:sby],'w','LineWidth',1.5);  % new y axis
% calculating 2nd padarray margins
dx2=D-(sx-x1);dx2=floor(dx2);
dy2=D-(sy-y1);dy2=floor(dy2);
B3=padarray(B,[dy2 dx2],50,'post');
[sb3y sb3x sb3z]=size(B3);
figure(4);imshow(B3);
xc2=floor(sb3x/2);yc2=floor(sb3y/2);
% visualizing initial image centre [xc yc] and and chosen rotation point [x1 y1]
hold all;figure(4);plot(xc2,yc2,'r*','MarkerSize',10);
hold all;figure(4);plot(xc2-(x1-xc),yc2-(y1-yc),'ro','MarkerSize',10);
% visualizing outer circle after 2nd padarray
 xd2=xd+xc2;
 yd2=yd+yc2;
hold all;figure(4);plot(xd,yd,'r','LineWidth',2.5);
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(4);plot([1:1:sb3x],ones(1,sb3x).*yc2,'w','LineWidth',1.5);  % new x axis
hold all;figure(4);plot(ones(1,sb3y).*xc2,[1:1:sb3y],'w','LineWidth',1.5);  % new y axis   
      case 3 % x1>xc & y1>yc
    D=norm([x1 y1]-[0 0]);
% 1st pair of padding margins
dx=D-x1;
dy=D-y1;
dx=floor(dx);dy=floor(dy);
B=padarray(A,[dy dx],'pre');
figure(2);imshow(B);
[sby sbx sbz]=size(B);
hold on;figure(2);plot(x1+dx,y1+dy,'r*','MarkerSize',10);
hold on;figure(2);plot(xc+dx,yc+dy,'ro','MarkerSize',10);
x0d=D*cos(t); xd=x0d+dx+x1;
y0d=D*sin(t); yd=y0d+dy+y1;
hold all;figure(2);plot(xd,yd,'r','LineWidth',1.5);
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(2);plot([1:1:sbx],ones(1,sbx).*(dy+y1),'w','LineWidth',1.5);  % new x axis
hold all;figure(2);plot(ones(1,sby).*(dx+x1),[1:1:sby],'w','LineWidth',1.5); % new y axis
% calculating 2nd padarray margins
dx2=2*D-sbx;dx2=floor(dx2);
dy2=2*D-sby;dy2=floor(dy2);
B2=padarray(B,[0 dx2],50,'post');
figure(3);imshow(B2);
B3=padarray(B2,[dy2 0],100,'post');
[sb3y sb3x sb3z]=size(B3)
figure(4);imshow(B3);
xc2=floor(sb3x/2);yc2=floor(sb3y/2);
% visualizing initial image centre [xc yc] and and chosen rotation point [x1 y1]
hold all;figure(4);plot(xc2,yc2,'r*','MarkerSize',10)'
hold all;figure(4);plot(xc2-(x1-xc),yc2-(y1-yc),'ro','MarkerSize',10)'
% visualizing outer circle after 2nd padarray
xd2=x0d+xc2;
yd2=y0d+yc2'
hold all;figure(4);plot(xd2,yd2,'r','LineWidth',2.5)'
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(4);plot([1:1:sb3x],ones(1,sb3x).*yc2,'w','LineWidth',1.5);  % new x axis
hold all;figure(4);plot(ones(1,sb3y)*xc2,[1:1:sb3y],'w','LineWidth',1.5);  % new y axis      
      case 4 % x1<xc & y1>yc
% D is distance between [x1 y1] and [xc yc], also D=pdist2([x1 y1],[sx 0])
D=norm([x1 y1]-[sx 0])
% 1st pair of padding margins
dx=D+x1-sx
alpha=atand((sx-x1)/y1)
s=(2*D^2-2*D^2*cosd(alpha))^.5
dy=(s^2-(sx-x1)^2)^.5
% dy=D-y1
dx=floor(dx);dy=floor(dy);
B=padarray(A,[dy,dx],'both');
figure(2);imshow(B)
[sby sbx sbz]=size(B)
hold on;figure(2);plot(x1+dx,y1+dy,'r*','MarkerSize',10)
hold on;figure(2);plot(xc+dx,yc+dy,'ro','MarkerSize',10)
% the origin has been displaced [-dx -dy]
% the point [x1 y1] to become rotation Z axis now has coordinates [dx+x1 +dy+y1]
% visualizing the outer rotation circle
x0d=D*cos(t); xd=x0d+dx+x1;
y0d=D*sin(t); yd=y0d+dy+y1;
hold all;figure(2);plot(xd,yd,'r','LineWidth',1.5);
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(2);plot([1:1:sbx],ones(1,sbx).*(dy+y1),'w','LineWidth',1.5)  % new x axis
hold all;figure(2);plot(ones(1,sby).*(dx+x1),[1:1:sby],'w','LineWidth',1.5)  % new y axis
% calculating 2nd padarray margins
dx2=2*D-sbx;dx2=floor(dx2);
dy2=2*D-sby;dy2=floor(dy2);
B2=padarray(B,[0 dx2],50,'pre');
figure(3);imshow(B2);
B3=padarray(B2,[dy2 0],100,'post');
[sb3y sb3x sb3z]=size(B3)
figure(4);imshow(B3);
% visualizing initial image centre [xc yc] and and chosen rotation point [x1 y1]
hold all;figure(4);plot(x1+dx+dx2,y1+dy,'r*','MarkerSize',10)
hold all;figure(4);plot(xc+dx+dx2,yc+dy,'ro','MarkerSize',10)
% visualizing outer circle after 2nd padarray
xd2=xd+dx2
yd2=yd
hold all;figure(4);plot(xd2,yd2,'r','LineWidth',2.5)
% visualizing axes after 2nd padarray and origin displacement
hold all;figure(4);plot([1:1:sb3x],ones(1,sb3x).*(dy+y1),'w','LineWidth',1.5)  % new x axis
hold all;figure(4);plot(ones(1,sb3y).*(dx+x1+dx2),[1:1:sb3y],'w','LineWidth',1.5)  % new y axis
      otherwise
          disp('\nerror\n')
          return
  end
  % 
  % imsave(B3)
  imwrite(B3,'padded_image.jpg')
  % padded image: B3
  % size square containing padded image: [sb3x sby3]
  % center padded image: [xc2 yc2]
  % points outer circle centre before rotation [xd2 yd2]
  % radius: D
B4=imrotate(B3,angle);
[sb4y sb4x sb4z]=size(B4);
figure(5);imshow(B4);
% visualizing initial image centre [xc yc] and and chosen rotation point [x1 y1]
hold all;figure(5);plot(floor(sb4x/2),floor(sb4y/2),'r*','MarkerSize',15);
% hold all;figure(5);plot(xc+dx+dx2,yc+dy,'ro','MarkerSize',10);
% visualizing outer circle after 2nd padarray
xd4=x0d+floor(sb4x/2);
yd4=y0d+floor(sb4y/2);
hold all;figure(5);plot(xd4,yd4,'r','LineWidth',2.5);
if angle>0 str1='CCW'; end;
if angle<0 str1='CW'; end;
figure(5);legend(['angle : ' num2str(angle) ' º ' str1],['Radius : ' num2str(floor(D)) ' pixels'],'Location','Northwest');
imwrite(B4,'im_padded_rotated.jpg');

If you find this answer of any help solving your question,

please click on the thumbs-up vote link, or mark is accepted answer

thanks in advance

John

jgb2012@sky.com

Best Answer

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