A server can handle multiple clients, each independently from the others. The GUI can be run separately, by itself, and can write the incoming image to disk if the user desires to use an image viewer different from the one provided. An obvious variation on PIT is to use a frame grabber to turn video into digital images, and then use PIT technology to send the grabbed video frames. The video frames can be large, like 640x480, and they can be big, like 24-bit RGB color. Install the .tcl files there too, but leave the .tcl suffix intact.
Workstations vary on the amount of shared memory they allow.
This program will probe for and use the maximum allowed amount, which must then be prorated for each image dimension. If you'd like to increase the shared memory limit, see your local guru. A better way to do this is to modify the kernel config file instead of this compile-time constant, but our information is sketchy here. After doing this either source your .cshrc and rehash, or log out and in again. See here for instructions.