Yes. The definition of the images is separate from the storage of the images. You can have one without the other, which is the situation such as when you create a new image in the web ui and before you upload the actual image. Conversely, if you delete the definition from the database, the file(s) can still exist if they are not deleted also. This means you can copy or move the image files to an external HD if they are no longer in use, but still leave the definitions in FOG. If you ever need to use the image again, just copy it back to the images folder.
To recover your “lost” image:
Create a new image in the Web UI by giving the new image definition the same type (single partition, mult-partition, etc) and specifying the correct storage location.
Example:
Image Name: Image1
Image Description: First Image, Win XP Pro 32 bit
Storage Group: Default
Image file: /images/[Name of file or folder that holds the image or image files]
Image type: [select correct image type]
If the image is stored in 1 file under /images/, such as a single parition-resizable image type, then put the filename as the value for the Image file: /images/[image file]
If the image is stored in a folder under /images/, such as a multiple-partition-single disk or multiple disk, then put the folder name that contains the image files.