To download a printable poster-sized (28" x 28", 144 ppi), click on the "Download a printable poster TIFF file" link which is found on each image page. The TIFF files available for download have been compressed with the gzip command to make their storage and transfer more manageable. Once the file has been downloaded you will need to expand the file. To expand the file follow the following directions depending upon which platform you use:

Macintosh: Use Stuffit Expander freeware.
Windows: Use either Stuffit Expander freeware or WinZip software.
UNIX: Use "gunzip" command.