Is it to possible to shift the subpixels in an image ? if possible how ?. Does matlab provide any algorithm for subpixels shifting?

Regards

th = (-90:90)';
th_r = th*pi/180;
x = cos(th_r)*(8-0.33*th_r.^2);
y = sin(th_r)*(8-0.33*th_r.^2);

My code is

for th=-90:90;
x(th+181)=cos((th*pi)/180)*(8-(0.33*((th*pi)/180))*((th*pi)/180));
y(th+181)=sin((th*pi)/180)*(8-(0.33*((th*pi)/180))*((th*pi)/180));
end
 plot(x,y), axis ij, axis equal, axis([-15 15 -15 15]), grid on
 theta = pi/4;
A2 = [cos(theta) sin(theta) 0; -sin(theta) cos(theta) 0; 0 0 1];
tform2 = maketform('affine', A2);

 uv = tformfwd(tform2, [x y]) %% after the execution of    %%this  line  

and the error appears to be in MATLAB are

??? Error using ==> tform>checkCoordinates at 141
Function TFORMFWD: SIZE(U) is inconsistent with T.ndims_in.

Error in ==> tform at 42
    [U, D] = checkCoordinates( f, P, A{1} );

Error in ==> tformfwd at 68
varargout = tform('fwd', nargout, varargin{:});

Any suggestions ?

To prevent this automatic (and unexpected) adjustment of the output pixel size, specify the ‘XYScale’ parameter to be 1, like this:

newimg = imtransform(oldimg, tform, 'XYScale', 1);

I had wrote the following codes:
{
xscale = 5;
yscale = 5;

rotation = 30;
oldimg = imread(’house.bmp’);

theta = rotation*pi/180;
As = [xscale 0; 0 yscale];
Ath = [cos(theta) -sin(theta);sin(theta) cos(theta)];
A = Ath*As;

T = eye(3,3);
T(1:2,1:2)=A;
tform=maketform(’affine’,T);
newimg = imtransform(oldimg,tform);
size(newimg)
figure,imshow(newimg);
}

My problem is as follows:

As xscale>=2 and yscale>=2, the size of the transfomed image is not the one I expected. In the above example, the size of the origin image is 256X256, however, the new image size is 513X513.

Suposse I have a squared ring as shown next,

%    ________17_______
%   |      _____      |
%   |     |     |     |5
%   |     |     |3    |
%   |     |__5__|     |  2*(5+17) units of outer perimeter
%   |_________________|  2*(3+5) units of inner perimeter

The function I am trying to design should out a result similar to the next figure,

%   _________20_________
%  |                    |
%  |        ____        |6
%  |       |    |2      |
%  |       |_4__|       |
%  |                    |  2*(6+20) units of outer perimeter
%  |____________________|  2*(2+4) units of inner perimeter

The main problem I have is that I don’t know how to remap the image in order to obtain those results.
I though in determining the euclidean distance from the image pixels to the background and try to expand the evaluated pixels towards the direcction where such distance is minimum but I dont know how to expand/contract the pixels according with the object boundary location in a coherent way.
Maybe there is no relation with the imopen funtcion I mentioned in the last question but I’ve shown by using the imdilate the results are quite similar as I need, however, the output image is blurred.

Thanks