Are there PAL/NTSC-unsafe CLUT values (for subtitles)?

[kumi]

I've been looking at the subtitles on some of my retail discs, and I've noticed many of the ones with white-on-black subtitles actually use off-white and off-black p/e1/e2 CLUT values. I don't have many discs with 255/255/255 RGB white or 0/0/0 RGB black.

That leads me to ask: do studios author this way to avoid NTSC or PAL-specific issues, and if so, are there some guidelines for choosing safe colors that I can follow?

Thank you :)

[r0lZ]

I don't think the choice of those off-white and black values are motived by NTSC or PAL considerations. IMO, they do that because pure white is somewhat dazzling, especially when displayed over dark scenes. (BTW, I prefer to use pure white but with a transparency level around 10. This way, the white appear dimmed on dark scenes, and really white on bright scenes.)

[mpucoder]

Yes, there are "illegal" CLUT values for NTSC (PAL/SECAM have no problem). Which set of values you want to avoid depends on the connection to the display. RF is the most restrictive because of modulation limits, composite is less restrictive, but must avoid the signal going negative enough to look like a sync tip. S-Video seperates the color from luminance, so only the color signal has restrictions (not the sum of luminance and chrominance as in composite).Component (YPbPr) has no problem. For a good explanation see this page (http://www.geocities.com/ResearchTriangle/3930/illegal_colors.html)

[kumi]

Thanks mpucoder. That page is way over my head, but I think I'll play it safe with slightly off-white and off-black, plus use <15 transparecies like r0lZ suggested, and I figure I'll be A-OK. :)

[r0lZ]

I ignored that, mpucoder. Thanks for the info.
BTW, IMO, it's again totally absurd. It should be the responsibility of the player to scale the colors to send compatible values to the display. Again, why make things simple when they can be complicated? (And again a bad point for the NTSC standard! ;))