The U.S. National Archives and Records Administration now provides access to high-resolution images of the Charters of Freedom documents. These files are in JPEG format with the maximum quality setting possible. These images will print at up to approximately 24" wide by 29" high at 150dpi (publication quality).
For graphic designers, each file also contains "clipping paths" for easy mask creation with most professional graphics software.
You can download these images here.