Getting color numbers at special coordinates

Hello to you all,
I wonder how it is possible to get the RBG color numbers (= between 0 and 255 for blue, red and yellow) of a pixel at special coordinates x and y. Does this feature is already implemented under GE or do I have to turn to the C language features? (In this case, do you have any idea how to use the C script in the right way?)
Many thanks!
I wonder how it is possible to get the RBG color numbers (= between 0 and 255 for blue, red and yellow) of a pixel at special coordinates x and y. Does this feature is already implemented under GE or do I have to turn to the C language features? (In this case, do you have any idea how to use the C script in the right way?)
Many thanks!