AD723 linear or log input?

[sirus]

I'm building a 24bit color board inspired by the uzebox. I see the resistor values are doubling. is this just to get the most color out of such a low bit per channel setup or does the ad723 need this for accurate color. I was going to make my 8bit r2r dacs with 1x 16 pin 8 resistor array in series with 2x 9 pin 8 resistor array chips in parallel with a resistor value of around 100k per resistor and then figuring out the correct termination resistor to get a max voltage as close to the AD723's max of 714mv

I'm running 3.3volt chips btw.

[HardlyUnique]

Is this just to get the most color out of such a low bit per channel setup or does the ad723 need this for accurate color.

Well, both. You would expect writing binary 010 to a color channel to yield roughly twice the intensity of 001. You would expect 100 to be twice as intense again. It's a linear relationship.

I can't speak to how possible what you're trying to do is but FWIW, I started out on a similar journey last year but had to postpone it. You may want to look into the chip I was going to use, the ADV7343 from Analog Devices. It's a dual NTSC / HDTV encoder with an onboard DAC that accepts 8:8:8 RGB.

[sirus]

ok linear so I can have an 8bit r2r with all 50k resistors and get a normal scale with proper voltage division