Capture whole screen as image

Here is the code

$im = imagegrabscreen();
imagepng($im, "myscreenshot.png");
imagedestroy($im);

Further Instructions:
For this to work your Apache service must be set to ‘Allow service to interact with desktop’ otherwise you will just get a blank image. To fix this right-click My Computer, select Manage/Services and Applications/Services – find the apache service (like Apache2) and right-click, select Properties – choose the Log on tab and check the ‘Allow service to interact with desktop’ checkbox. Restart Apache.