Do you need to format a flash drive before dd an image to it?

Question

Does dd or Windows Image Writer work regardless whether the target device was formatted or partitioned correctly?

I'm trying to flash a Chromium OS build to a USB flash drive following these instructions.

Answer 1

Yes (you don't need to partition the drive). When you write directly to a block device (/dev/sdX) with dd, you are overwriting any partition table currently on the drive.

I haven't ever used (or heard of) Windows Image Writer, but if it's similar to dd, it writes raw data to the drive, regardless of what was present before.