how to find the translation for x and y in order to align edge detected images

Find the translation required in the x and y coordinates in order to align edge detected images. Align the edge detected images of the second and the third parts (G and R) to the first (B). The easiest way to align the parts is to exhaustively search over a window of possible displacements using the "circshift" MATLAB function. Score each one using an image matching metric, and take the displacement with the best score. Use the sum of squared difference metric to measure how well images match: Sum of squared differences: sum( (image1-image2).^2 ) For each image, you will need to record the displacements in x and y that were used to align the parts; make sure to state whether it is (y,x) or (x,y) because typically the first coordinate in MATLAB is the vertical component

Please help!

Answer 1

[Image Analyst]

A couple of for loops with circshift() and your sum equation inside should do it. Just be sure to cast your images to single or double before you subtract them so that you can get negative values and not have them clip at zero.

[Tezel]

can you show us how to do a for loop using the shift function please or are there like any tutorials or anything

[Image Analyst]

You never did look up circshift(), did you? Sounds like this is homework, so here's a hint

for rowShift = -10:10
  for colShift = -10:10
    shiftedImage = circshift(single(originalImage), [rowShift, colShift]);
    % Construct difference image.
    diffImage = single(shiftedImage) - shiftedImage;
    % Now construct sum
    % Then find which shift gives best match (minimum sum).
  end
end

[Pretzel]

Hi. I have the same problem as above. But i am confused as to what difference are we actually seeking for. Do we need the difference of the entire images or we are moving a window and need to calculate the difference only within that window. Also can you please tell after we get the ssd with the minimum score, how do we align the images with that?? I am searching a lot to get this clear, but unable to find a proper explanation for the same.

Please help!

[Image Analyst]

I really would not use the method his assignment said to use since MATLAB has a built in function to do the alignment. Just use imregister() in the Image Processing Toolbox. You might be able to do it on the grayscale images instead of the edge images.

[Pretzel]

My assignment requires me to align three images, namely the R,G,B color channels of the same image, to form one color image. In order to do so, I am required to find out the displacement vector , of R and G , keeping B as the reference image, and then align accordingly. But I am confused as to how to find the displacement vector by ssd. Its really urgent, please help. Thanks a lot!

[Image Analyst]

I think you should start your own discussion rather than continue nita's which I think will send her emails about your problem. And when you do, explain how and why the red, green, and blue got displaced in the first place, and attach your image and code where you attempted to use imregister to align them.