windows - Getting pixel color in C++

Question

I would like to get the RGB values of a pixel at different x, y coordinates on the screen. How would I go about this in C++?

I'm trying to create my own gaussian blur effect.

This would be in Windows 7.

Edit

What libraries need to be included for this to run?

What I have going:

#include <iostream>

using namespace std ;

int main(){

    HDC dc = GetDC(NULL);
    COLORREF color = GetPixel(dc, 0, 0);
    ReleaseDC(NULL, dc);

    cout << color; 

}

Answer 1

You can use GetDC on the NULL window to get a device context for the whole screen, and can follow that up with a call to GetPixel:

HDC dc = GetDC(NULL);
COLORREF color = GetPixel(dc, x, y);
ReleaseDC(NULL, dc);

Of course, you'd want to only acquire and release the device context once while doing all the pixel-reading for efficiency.