Different sizes in Creating an ISO

[Heckenschneider]

Hello.

If I add "Windows22H2.iso", convert it completely to WIM, and then create the ISO, it's 5718 MB.

If I then load an edition, click "Apply" without making any changes, and then check "Create ISO" without any further editing (it all remains WIM), the ISO is 5706 MB.

The difference isn't huge, but it should be the same in both cases.

What's the difference "under the hood"?

Thanks.

 

[garlin]

NTLite depends on the open-source wimlib to handle WIM/ESD extraction and compression. When you load an image, it's extracted to a mount folder. During processing, all the mount folder's contents are re-compressed (to capture any potential changes in the folder's directories).

It's too expensive for NTLite to do file comparisons to check if nothing was actually touched in the mount, so it can't simply assume that you didn't modify something in the mount folders outside of NTLite's control. Thus, it must convert the mount folder back to a WIM or ESD.

You'll get minor differences in sizes, because wimlib is doing the compression, and it may not have the same optimization settings. wimlib creates a compatible image, but it's not using the exact same algorithm as MS.

 

[Heckenschneider]

understood