print a screenshot of the desktop and convert in to a matrix of pixels[0,1]

I want to build a program that prints the current screen (every few seconds) and searches for symbol in it. I already have the function that knows how to find a given symbol in a larger function, however I do not have the followings:

1. How can i c开发者_运维百科apture the current screen (print screen).
2. How do i convert the picture into a matrix of pixels in the range of [0,1], meaning black and white picture.

Currently i only know Java , C , C++, so i need solutions in one of these languages.

I suppose that writing such code may be beyond my knowledge so, links to tutorials will be gladly accepted.

Thank you

I just did a google search and came up with this, and this. HTH