Alternatively, if you want better than crappy composite, s-video is proper NTSC as well (handy if you're out of rgb scarts, or you want to use the ps2 as a dvd player without hacking/re-enabling rgb, assuming you can find a ps2 s-video lead).
Finding the extra picture setting to tweak ("tint" on my panasonic) is a giveaway that your TV is displaying NTSC.