can you tell me the difference between BLOCK and FILE type image
It specifies if the image is captured at the hard drive block level or file level. Block is much faster, you cannot restore a block image to a device that is smaller, that is why the filesystem is shrunk. File does not have that limitation, so shrinking the filesystem is not necessary. File images can be mounted in Windows and modified, block cannot. Most of the time I would stick with Block because it has been tested more, but sometimes it might be useful to use file. File currently only works ntfs, but ext and xfs will be supported in the next version.