Re: [microsound] [ot] RGB freq?

[Ian Andrews <i.andrews@xxxxxxxxxxxxxxxxxx>]

>NTSC (US/Japan TVs) encodes color information on a high-frequency carrier
>on *top* of the low frequency luminosity channel -- a testament to the
>history of television; and a very elegant solution to the question of how
>black and white TVs handle color signals: they just low-pass filter out
>all the color info!
>
>This is also why you're not supposed to wear herringbone on TV -- the
>high-frequency encoding of the black/white pattern starts to slip through
>the high-pass color path and you get "chroma creep" -- rainbow washes --
>where you don't want them.
>
>This is also why you want "component" video in/outputs on your DVD player
>and TV -- no crosstalk!
>
>There are specific frequencies in NTSC that correspond to specific colors
>as I recall -- here's an interesting tutorial google coughs up:
>
Not exactly.  There is only one frequency in NTSC (3.53MHz) and the colours
are depicted by different phase relations of this frequency. Its called
quadrature phase. The colour subcarrier (3.53MHz NTSC 4.43MHz PAL) is
modulated on two axi 90 degrees apart. So each colour is mathematically
represented by a vector, in which the amplitude of the vector determines
the saturation of the colour and the phase angle of the vector determines
the hue of the colour.

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