Posted by PTravel on 07/03/06 01:28

"Martin Heffels" <youwishyouwouldknow@nottellinya.com> wrote in message
news:hfiga2t7ffprp0nce5eu1mdldo0aa83lnt@4ax.com...
> On Sun, 02 Jul 2006 22:17:40 GMT, "PTravel" <ptravel@travelersvideo.com>
> wrote:
>
>>I was thinking more in line with the video equivalent of an audio
>>compander -- something that can take the limited range that's available
>>and
>>expand it. For example, if Na lights put out light limited to 240-245
>>angstroms (I'm just making up numbers here), something that would
>>extrapolate on the video so that the lower range fell closer to red and
>>the
>>upper range closer to blue would provide a more varied, albeit false,
>>coloration.
>>
>>Hmmm. Have I just invented a new filter?
>
> Want to have Ira Tiffen's e-mail address? :-)
>
> You could with some clever mathematics expand the range and fill in the
> gap
> on your computer,

That's exactly my thought.

> but it won't help you with the environment the
> sodium-vapour lamps are lighting. Your green rental car will still look
> like it has been "pimped" to black while you were eating in the restaurant
> :-) And if you didn't remember the license plate......

Because the green car will reflect some of the higher bandwidth "spill" from
the sodium vapor light, whereas the dark red sweater will reflect some of
the lower bandwidth spill. It should be possible to mathematically expand
the departure from the "pure" color of the sodium lamp to produce a false,
but more varied, color spectrum. The key, here, is that the sodium vapor
lamp contains impurities and does output light only at the single spectrum
for Na.

>
> cheers
>
> -martin-
> --
> "If he can he'll smile 'cos he's a Royal Crocodile."
>
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