i just noticed on my Nikon L - 820 point and shoot camera, i am able to take (( HDR )) PHOTOS ?? ON MY SCENE MODE ON MY CAMERA, THERE IS A SETTING CALLED (( BACK LIGHTING )). I HIT THAT SETTING, AND IT ASKS IF I WANT TO DO THE SHOT IN (( HDR )) OR TURN IT OFF. MY QUESTION, IS WHAT IS (( HDR )) ??? AND WHAT DOES IT DO ??