My guess is that it might have a negative effect on rendering energy consumption.<p>In OS X you can use CoreImage to filter a view, but that has always been excluded from iOS.<p>The platform perception management kicks in, they can&#x27;t let all the cool kids install a filter on top of all the rendering then complain that iPad and iPhone battery life sucks.<p>In my own Sudoku program I automatically manage the screen white point by sensing the backlight level (I&#x27;m not allowed to use the ambient light sensor, so I watch something that watches it.) but I have to do it by changing all of my colors everywhere I draw. It&#x27;s not a big deal and works beautifully, until you finish a puzzle and the pure iOS alert comes up in full white and burns a hole straight through your drowsy dark adapted retinas. Then you have to go to sleep because you have a huge afterimage floating around in the center of your vision.