Colored hides and garments are not susceptible to nega impurity. Rabbi Meir says that houses are susceptible to negaim regardless of whether they’re colored or not. Rabbi Yehuda says that hides are like houses; Rabbi Shimon says that naturally-colored hides are susceptible to nega impurity but those that were dyed by man are not susceptible.
If a garment’s warp threads were colored and its woof threads were white, or vice versa, then everything follows what’s visible. Garments contract impurity through the brightest shade of green or red. If the nega was green and it spread red, or vice versa, it is unclean. If the spot changed color and then spread, or if it changed color and didn’t spread, it’s treated as if it didn’t change. Rabbi Yehuda says that it should be inspected as at the outset.