How can I avoid a program from capturing the image on my screen? Is there any API that can enable and disable capturing? It's urgent. Can any one help me?

No it isn't possible. Even if you would find a way to disable the standard windows screen capture you could still use one of those screen capture programs. See the way it works is that there is a main window which all the programs are allowed to write and read from. So they will always be allowed to read your data from the screen. I don't know exactly what your trying to do this for. But although you can't disable it you could apply a few tricks to make it really hard for them to capture the screen. First you should try to make your program take up the whole screen. Full screen mode without start menu and stuff. So all they see is your program. After that you'll need to write a keyboard handler which catches every keyboard event. This will prevent then from activating any other program using a key combination. There are still ways around it then but you'll have to go through a lot of trouble to capture the screen. Mik

One way I have avoided people from copying data or screen designs from my app is by clearing the clipboard when my screen/application looses focus.