The RGBW sensor looks very tempting...
Another point; I'm not sure if people are suggesting taking the 4 channels out of an RGBW and using them to drive the RGBW strips? I.e., take R reading from sensor and drive red LEDs accordingly, take W reading from sensor and drive white LEDs accordingly... Because if that's what is being suggested, that's a terrible idea. Consider what happens if you ask this system to reproduce a pure red laser. Both the R and W channels of the RGBW sensor will respond, and therefore both the Red and White LEDs in the strip will light up. But this is obviously the wrong thing to do; the best impersonation an RGBW strip can do of a red laser is to turn the red LEDs on only. Turning the white LEDs on as well would just wash out the colour.
This is why it's preferable to use some sort of basic feedback or calibration/characterisation; and once you're doing that the W channel of the sensor is of very little value.
One of the problems of a cam might be the dynamic range of a prosumer/consumer cam (like the EOS D5 Mk3 that is floating around here). Starting a the blue hour running until the sun is reasonable above the horizon is probably too much. So you need to take care there too. Not impossible but something you need to take care of.
Fixed ISO + Aperture, but leave the camera to choose a shutter speed. Check the EXIF data to compensate. Also, whether you actually want to be matching the brightness of a real sunset is questionable; I highly doubt that your LED strips can compete with direct sunlight. So you're going to want to deliberately compress your dynamic range anyway.
Thanks for the heads up with the non linearity of the standard colour system. One more reason to use the RGB sensor. You can keep the whole flow relatively controlled.
Meh, I'm suggesting just calibrating the whole RGBW strip + camera filters + RGB transform as a single black box -- that's the beauty of this approach, you don't
need to tease these things apart at all.
The only pitfall here I see is the room-calibration. In case the LED colours don't match reasonable with the filters of the sensor.
No, you explicitly
don't need to worry about this! That's what the calibration is for. As long as you trust that your eyes have the same response as the digital camera; everything else is sorted.
But hey, whatever floats your boat. I guess it's plausible to claim that the response of the RGB filters of the
chip recommended earlier (just ignore the W honestly, it extends way too far into the NIR) are closer to that of the human eye than the filters on a typical digital camera. And there's nothing inherently wrong with using the sensor, it's just that it feels to me like a lot more work.