Can you scan the color values of all pixels on the screen in a given frame?

Question

Note: The Scanning does not have to be done in the same frame.

Answer 1

The PrintWindow call in the Windows API can grab a bitmap of a window.

This example is not in Java, but it's the idea*
https://stackoverflow.com/a/7292773

* My system's also hitting a memory limit, have to restart, will edit in a Java sample if I find one.

edit: working Java sample:
https://stackoverflow.com/a/4682351

From question:
https://stackoverflow.com/questions/4433994/java-window-image