Also know how to use the help command in Matlab
Knowledge of Photoshop, SnagIt or similar programs is a plus
Desire to stitch together images to gain full view of a scene
In addition, would like to learn more about Matlab commands and scripts
Construction
Programming
Final Words
Mathworks
TechSmith
(example: above left photo is titled "left.jpg" and above right photo is titled "right.jpg".)
Open Matlab program on the personal computer you are working on.
Make sure the mosaic.m script is also saved within the Matlab folder on the personal computer you are working on.
In the Matlab command window, select the File menu, and select run script. A window will appear asking you for the file name of the script you wish to run. Select Browse, and find the mosaic.m script, highlight it, click on Open, and click on OK.
A new window will appear entitled 'Figure No. 1'. The first input image will appear (in our example: 'left.jpg'). The mouse will move the crosshair lines. Click on the first point which you preselected in Step 1. A red cross will appear at that point with the number 1 next to it.
Use the mouse again to click on the 2nd pre-selected point from step 1. A red cross with the number 2 will appear next to that point. Also, the second input image (in our example, 'right.jpg') will also now appear in the Figure 1 window.
Click on the matching point within the second input image for point 1. A red cross with a number 1 will appear at that point in the second input image.
Use the mouse again to click on the matching point within the second input image for point 2.
When this is done, a new window will appear entitled Figure No. 2. This is the mosaic image of the 2 input images.
Review the mosaic image in Figure No. 2.
If the image is distorted, at odd angles, or in general not satisfactory to what you had hoped to achieve, pre-select different points within the images, and repeat Steps 1 through 9 again.
If the image is satisfactory, click on the File menu within the Figure No. 2 window. Click on Save As, and name the file. This will only save this file as an .fig file for Matlab. ***Keep the Figure No. 2 window open***
Use software such as SnagIt to capture the mosaic image, with or without the graph lines, and save it to a .jpg, .gif, .bmp, or other type of file format.
Note: download warping.zip rather than cutting and pasting from below.
Use unzipping software to unzip the warping file. The mosaic m file is included.
% load input images
I1 = double(imread('left.jpg'));
[h1 w1 d1] = size(I1);
I2 = double(imread('right.jpg'));
[h2 w2 d2] = size(I2);
% show input images and prompt for correspondences
figure; subplot(1,2,1); image(I1/255); axis image; hold on;
title('first input image');
[X1 Y1] = ginput2(2); % get two points from the user
subplot(1,2,2); image(I2/255); axis image; hold on;
title('second input image');
[X2 Y2] = ginput2(2); % get two points from the user
% estimate parameter vector (t)
Z = [ X2'; Y2' ; Y2' -X2' ; 1 1 0 0; ; 0 0 1 1 ]';
xp = [ X1 ; Y1 ];
t = Z \ xp; % solve the linear system
a = t(1); % = s cos(alpha)
b = t(2); % = s sin(alpha)
tx = t(3);
ty = t(4);
% construct transformation matrix (T)
T = [a b tx ; -b a ty ; 0 0 1];
% warp incoming corners to determine the size of the output image (in to out)
cp = T*[ 1 1 w2 w2 ; 1 h2 1 h2 ; 1 1 1 1 ];
Xpr = min( [ cp(1,:) 0 ] ) : max( [cp(1,:) w1] ); % min x : max x
Ypr = min( [ cp(2,:) 0 ] ) : max( [cp(2,:) h1] ); % min y : max y
[Xp,Yp] = ndgrid(Xpr,Ypr);
[wp hp] = size(Xp); % = size(Yp)
% do backwards transform (from out to in)
X = T \ [ Xp(:) Yp(:) ones(wp*hp,1) ]'; % warp
% re-sample pixel values with bilinear interpolation
clear Ip;
xI = reshape( X(1,:),wp,hp)';
yI = reshape( X(2,:),wp,hp)';
Ip(:,:,1) = interp2(I2(:,:,1), xI, yI, '*bilinear'); % red
Ip(:,:,2) = interp2(I2(:,:,2), xI, yI, '*bilinear'); % green
Ip(:,:,3) = interp2(I2(:,:,3), xI, yI, '*bilinear'); % blue
% offset and copy original image into the warped image
offset = -round( [ min( [ cp(1,:) 0 ] ) min( [ cp(2,:) 0 ] ) ] );
Ip(1+offset(2):h1+offset(2),1+offset(1):w1+offset(1),:) =
double(I1(1:h1,1:w1,:));
% show the result
figure; image(Ip/255); axis image;
title('mosaic image');