Images convertion between Qemu and VirtualBox

VDI to QCOW:
VBoxManage clonehd image.vdi image.img –format RAW
qemu-img convert -f raw image.img -O qcow2 image.qcow2

QCOW to VDI:
qemu-img convert image.qcow2 -O raw image.raw
VBoxManage convertdd image.raw image.vdi