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Posted by R. Mark Clayton on 10/10/06 12:48
>> >
>
> In the old days when only B&W TV existed, was anythere any such thing
> as a "subcarrier" in the video signal?
The main signal was the picture, which was analog "black and white" - so you
got all the greys in between.
>
> B&W TV had only greyscale. So I think that there would be something
> similar to color subcarrier, except the "colors" would actually be
> different shades of gray along with black and white. After all, images
> couldn't convey much with just pure black and pure white, there needs
> to be grays of different darkness in order to add some meaning to the
> image.
Er yes. B&W is more properly monochrome [greys].
The colours were represented in different ways according to the system used,
however most used a difference for two colours, leaving the third as what
was left from the white signal.
>
> Converting an analogue greyscale image to a 1-bit digital image signal
> will result in the greys turning into pure black and/or white. The
> lighter greys would turn pure white while the darker greys would turn
> pure black.
>
Er yes! What has this got to do with it?
I think you are confusing the generic term 'black and white TV' (monochrome)
with literal black and white single bit images (e.g. a fax, where you have
to dither to get grey).
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