Step 5: Using XData and YData Input Parameters :: Spatial Transformations (Image Processing Toolbox User's Guide)

Image Processing Toolbox User's Guide

Step 5: Using XData and YData Input Parameters

One way to ensure that the registered image appears registered with the base image is to truncate the registered image by discarding any areas that would extrapolate beyond the extent of the base image. You use the 'XData' and 'YData' parameters to do this.

registered1 = imtransform(unregistered,tform,...
                          'FillValues', 255,...
                          'XData', [1 size(base,2)],...
                          'YData', [1 size(base,1)]);

Display the registered image, overlaying a semitransparent version of the base image for comparison. The registration is evident, but part of the unregistered image has been discarded. The next step provides another solution in which the entire registered image is visible.

figure; imshow(registered1)
hold on
h = imshow(base, gray(256));
set(h, 'AlphaData', 0.6)

Registered Image Truncated with Base Image Overlay

Step 4: Transform the Unregistered Image Step 6: Using XData and YData Output Values