qemu-img is a command line disk converter that allows you to convert virtual machine hard drive images between a variety of formats including IMG, VMDK, VHD, VHDX, COW2, VDI, and more.
qemu-img is part of the qemu-utils package and can be installed on Debian and Ubuntu linux machines using the following command.
sudo apt-get install qemu-utils
Once installed, run
man qemu-img to get instructions or click here.
The qemu-utils package also includes the following tools
qemu-img- QEMU disk image utility.
qemu-ndb- Exports QEMU disk images using NBD protocol.
qemu-io- A command line utility to exercise the QEMU I/O path.
qemu-make-debian-root- Creates a debian root image for qemu.
There is also a windows version of qemu-img that I have successfully used.
QEMU is short for Quick Emulator