PHP Code:
#include <windows.h>
#include <stdio.h>
#include <conio.h>

int main()
{
    RECT SpriteOne;        // Imaginary sprite
    RECT SpriteTwo;        // Imaginary sprite
    RECT SpriteResult;    // Sprite to hold overlapping area
    SetRect(&SpriteOne,50,50,100,100);   // A 50x50px sprite, with top-left @ (50,50)
    SetRect(&SpriteTwo,300,300,425,350); // A 125x50px sprite, with top-left @ (300,300)
    // Loop until they overlap
    while(!IntersectRect(&SpriteResult,&SpriteOne,&SpriteTwo))
    {
        // Simulate movement of the sprites
        SpriteOne.bottom += 1;
        SpriteOne.left += 1;
        SpriteOne.right    += 1;
        SpriteOne.top += 1;
        SpriteTwo.bottom -= 1;
        SpriteTwo.left -= 1;
        SpriteTwo.right -= 1;
        SpriteTwo.top -= 1;
    }    
    // Output the coordinates of the area where the sprites overlap
    printf("The rectangles have intersected!\nHere are the coords for pixel-perfect examination:\nLeft: %ldpx\nTop: %ldpx\nRight: %ldpx\nBottom: %ldpx\n\nPress any key to continue...",SpriteResult.left,SpriteResult.top,SpriteResult.right,SpriteResult.bottom);
    getch();
    return 0;
} 
This would allow you to do pixel-perfect collision detection only where the sprites overlap. Don't forget that .bottom = .top + height, and .right = .left + width.