I think relaying the image with a lens onto the colorimeter should work assuming you modify the game so the hardware displays a full screen equivalent of all po

I think relaying the image with a lens onto the colorimeter should work assuming you modify the game so the hardware displays a full screen equivalent of all possible variations of a single pixel. it might be necessary to switch to a color cube with 3 photodiodes, and perhaps read in with 3 DC-coupled audio channels, or alternatively use an arduino's ADC (I know ...) but with a proper antialiasing filter capacitor for the sample rate used.