what does ntsc colors does?

what does ntsc colors does?

Post by Vitor Viei » Wed, 23 Sep 1998 04:00:00



What does this filter do? I've tried out and it stays the same, and
some filter become unavailable.
could someone please tell me?

thank you

 
 
 

what does ntsc colors does?

Post by Mark Hanso » Thu, 24 Sep 1998 04:00:00



> What does this filter do? I've tried out and it stays the same, and
> some filter become unavailable.
> could someone please tell me?

> thank you

    NTSC Colors modifies any vivid reds and blues in an RGB or Lab image
so those colors don't bleed into others when it's transferred to video.
I believe it's technically against the law to transmit certain colors
over the air, though I doubt the FCC would come to arrest you down if
you did.
    I've never put this filter to use (and probably never will), but
it's pretty lame, from what I've heard. If you modify your image after
running this filter, you could very well have to run it again if the
colors have been affected.
    It's not even a real filter, for that matter. It should probably be
an action.

    Mark

 
 
 

what does ntsc colors does?

Post by Mel Matsuo » Thu, 24 Sep 1998 04:00:00




>> What does this filter do? I've tried out and it stays the same, and
>> some filter become unavailable.
>> could someone please tell me?

>> thank you

>    NTSC Colors modifies any vivid reds and blues in an RGB or Lab image
>so those colors don't bleed into others when it's transferred to video.
>I believe it's technically against the law to transmit certain colors
>over the air, though I doubt the FCC would come to arrest you down if
>you did.

I havent researched any specific FCC regulations regarding this, so I may be
mistaken, but ive worked in the video industry for many years, and believe that
the (possibly) erroneous notion that highly saturated NTSC colors are "against
the law" mainly stems from the use of the term "legal/illegal levels" among
engineers and broadcasters.

It's not really color that is the issue per se, but rather its *brightness*
level. Luminance levels in NTSC are measured in IRE (Institute of Radio
Engineers) levels, which basically represents the voltage level of the signal.
For various boring and arcane technical reasons, a "legal" NTSC signal
(translated, "a video signal that makes TV broadcasters and high-priced
equipment happy) cannot exceed 100 IRE without making certain broadcasting
equipment complain or go haywire.

Basically, its similar to a color gamut in print. So if you create graphics for
broadcast, you shouldnt use highly saturated colors, such as a "255, 255, 255"
white or yellow. Not only can there be problems with exceeding 100 IRE, but the
edges of certain color combinations/saturations can "shimmer" like mad (known as
"dot crawl") on TV.  

If you have ever seen a cheap commercial for a used-car dealership where the
audio "buzzes" whenever a title or graphic appears on screen, this is usually
indicative of "illegal" video levels, which ends up interfering with the audio
carrier.

I suppose that it /may/ actually be illegal to broadcast these colors, but the
FCC doesnt bother enforcing it these days, what with the ubiquity of cable
television, which i would guess is far less problematic now than back when TV
came to your house as-God-intended-it-to-be, i.e. through the airwaves.

Quote:>    I've never put this filter to use (and probably never will), but
>it's pretty lame, from what I've heard. If you modify your image after
>running this filter, you could very well have to run it again if the
>colors have been affected.
>    It's not even a real filter, for that matter. It should probably be
>an action.

>    Mark

____________________________________________________________________________
mel matsuoka                                Hawaiian Image Video Productions
Editor/Digital Media Dude                       http://www.hawaiianimage.com

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