Determine a proper compression level for your current backup task. The Normal option is selected by default and is recommended, but you may also select Higher or None. See more details as follows:
None: Data will be imaged without any compression, so the image file size will be equal to your original data.
Normal: Data will be compressed to a moderate level. It is a recommended compression level. (Default)
High: A much higher compression level is used during the backup. The image file will be smaller than other levels but the backup will take longer to complete.
Please note some kinds of file are essentially compressed, such as .jpg, .pdf or .mp3. If your backup contains many such files, the generated image file might not significantly decrease even when High compression level is selected.