GPUhub currently does not support importing custom images.
Save Image
After shutting down an instance, you can save the entire system disk of that instance by clicking “Save Image” in the “More” menu. (What system disk is?)
View saved images in the “My Images” menu.
Load Image
When creating a new instance or replacing the image of an existing instance, select the saved image you created to restore all the contents of the original instance’s system disk.
Share Image
After saving an image, you can click “Share” in the actions menu to share it with specific users.