why this command: a([],[],:)=A doesn't work? I try not to use for command

UPDATED: Finally I used bsxfun

---

   %I is a  512*512 picture
    outImg=uint8(zeros(512,512,3)); 
    tempImg=I(:,:,1:3);
    a=1;b=1;
    for i=1:iTimes   
                temp=tempImg;  

                ax=mod((a*b+1)*((1:512)-1)-b*((1:512)-1),512)+1;
                ay=mod(-a*((1:512)-1)+((1:512)-1),512)+1  ;

                outImg(ax,ay,1:3)=temp;  %this command does't work  why ?
      tempImg=outImg;  
    end  
    outImg=tempImg;

figure
imshow(outImg);

when I debugged, I found outImg was still zeros.

But the following command works.

A=zeros(2,2,3);
A(1,1,1)=6;
A(2,1,2)=6;
A(2,2,3)=6;
E=zeros(2,2,3);
E([1 2],[2 1],:)=A

A(:,:,1) =

     6     0
     0     0

A(:,:,2) =

     0     0
     6     0

A(:,:,3) =

     0     0
     0     6
  E(:,:,1) =

     0     6
     0     0

E(:,:,2) =

     0     0
     0     6

E(:,:,3) =

     0     0
     6     0

I want to avoid using "for" command

      for i=1:iTimes   
        for u=1:iH  
            for v=1:iW  
                temp=tempImg(u,v,1:3);  
%arnold transform
                bx=mod((a*b+1)*(u-1)-b*(v-1),iW)+1;
                by=mod(-a*(u-1)+(v-1),iW)+1  ;  
  % record address of pixels after transforming
  %     X_1(u,v)=(bx);
  %     X_2(u,v)=(by);
                outImg(bx,by,1:3)=temp;  
            end  
        end  
      tempImg=outImg;  
    end  
    outImg=tempImg;

Answer 1

[Roger Stafford]

As you have defined ax and ay, they are:

ax = 1:512;

and

ay = ones(1,512);

Just look at them to see that. This means that in

outImg(ax,ay,1:3)=temp;

you are attempting to stuff the entire image into the top row of outImg, and that won’t work. You need to rethink what you are trying to accomplish.

[KIKi]

I want to avoid using "for" command

      for i=1:iTimes   
        for u=1:iH  
            for v=1:iW  
                temp=tempImg(u,v,1:3);  
%arnold transform
                bx=mod((a*b+1)*(u-1)-b*(v-1),iW)+1;
                by=mod(-a*(u-1)+(v-1),iW)+1  ;  
% record address of pixels after transforming
%     X_1(u,v)=(bx);
%     X_2(u,v)=(by);

                outImg(bx,by,1:3)=temp;  
            end  
        end  
      tempImg=outImg;  
    end  
    outImg=tempImg;

I found

 (X_1(i,j),X_2(i,j))~=(ax(i),ay(j))