Shifting an image using the image processing toolbox

[urquidio]

Hi there,

I would like to use the 'affine' transformation in the image processing toolbox to quickly
shift an image in MATLAB.

Currently, I have the following code:

% -------------------------------------------------
% read in the image
I = imread('lena.tif');

% transform
T = maketform('affine',[1 0 0; 0 -1 0 ; 0 0 1]);
I2 = imtransform(I,T);

% show the result
imshow(I2)
% -------------------------------------------------


this flips the image I upside down. Now i want to shift
it by a certain amount, say del_x pixels in the x direction
and del_y in the y direction.

I'm thinking that i need to add a shift into the transformation, which seems to me that it should be added
in the last column of the matrix:

T = maketform('affine',[1 0 x; 0 -1 y ; 0 0 1]);
or something like that. but MATLAB requires that the last column is [0, 0, 1]. how do you get around this to get the affine transformation to perform a shift of the image?

thanks in advance

-M

 

[cah2oeng]

I actually have a similar need as well, but instead of a uniform shift in x, I'd like to have the shift in x be a function of y. Not sure this is even possible, but it's worth a try since right now, I am shifting pixel by pixel in with a fortran script.