MacDrive Standard offers a feature to "mount" or access the contents of unencrypted DMG files. This feature was implemented in MacDrive 7 (and newer). Prior versions of MacDrive, including MacDrive 6, cannot access DMG files.
Sparse image files are supported in MacDrive Pro (not Standard). MacDrive does not support Sparse bundles, however.
Please note that our support for DMGs and Sparse images is limited to those which are unencrypted. MacDrive does not support encrypted disk images (or disks).