Shrink the Disk Image

Trying Carbon Copy Cloner to copy the whole DVD to disk image. Unselect language packages, printer drivers, and Xcode tools; Using block level copy to new sparse image. After the copy completion, you mount the disk image and you can find the used size is < 4.7G but the disk size is ~= original DVD size. Because the underlay partition and file system is still the same as them in DVD. However, just run this 'hdiutil resize -size min xxx.sparseimage'. It will shrink the partition and file system size to possible minimum.
Note: If you delete some file and resize it, the disk size is still not changed because some files might be still occupied in the tail of the file system.