Do Color Roundies Have DC Restoration?

[compucat]

I was just wondering because my Zenith has such a good level of contrast with the controls set at a very moderate level. Many tube color TVs I have encountered years ago always had a soft picture compared to the contrast of a tube type black and white. I guess I'm surprised these sets perform so well considering they are the early stages of color TV development. I know the Portacolor has no DC restoration but I wonder if many other color tube sets lacked it as well.