@harryc1127 The compression format used by FOG is open source.
By default FOG uses gzip format for image compression. The FOG developers have added a new compression format that is much faster decompressing than gzip called ZSTD.
But in the end you will have a much quicker experience if you deploy your base image with FOG and then recapture with clonezilla (without letting the final target OS boot). The raw data files are one thing, but there is also the issue with the metadata files that are stored with the image information.
If you captured the source computers as single disk resizable, FOG will shrink the partition size on the reference image to the size of the data on the disk. Then FOG captures the image. If you take these compressed and shrunken disk image files, you can convert them to be used by Clonezilla but when you deploy them the partition sizes will be just a tad bigger than the data on the disk. Clonezilla won’t know how to expand the partition relative to the size of the disks. That is because that information is stored in the FOG meta data.
Its much quicker and easier to deploy with FOG and then turn right around and recapture with clonezilla. Depending on the size of your golden image and the speed of the target computer you are probably talking 15 minutes tops to deploy and then recapture with clonezilla.
But you can do it how ever you feel fits your situation. I’m only suggesting how I would go about it.