[filmscanners] Re: CRTs vs LCDs

["Dave King" <kingphoto@mindspring.com>]

>>Dave King <kingphoto@mindspring.com>, wrote:
>>I was thinking further about this today and realized I don't know what
>>the bias adjustment does.  Many monitors only have gain controls, and so
>>now I'm wondering how bias is different than gain, how it's used during
>>calibration, and the advantages (?) for color critical work. Thanks,
>>Dave

>Well, tech speaking about gain and bias:
>Say, you have an input X on monitor
>Your output will be Y = mX + b.
>Where m is the gain and b the bias aka offset.
>
>So what you see on screen (Y) is the signal (X) that comes from video
>card multiplied by gain (m) and added with b (offset or bias).
>In a perfect monitor you would have something like m= 1 and b = 0 so
>that the signal displayed by monitor is the same as the one that comes
>from the video card. But as monitors age they need to be recalibrated to
>show the desired signal so the need for the gain and bias.
>
>Hope I was clear and helped,
>Nuno Sebastião


Well, I was satisfied by Julian's answer, it was easy and practical.  But
your answer has me wondering again about what is actually happening at the
circuit level.  I guess they are voltage amplifiers operating at different
frequencies?  Presumably the gain control isn't particularly critical in
real world terms for color correcting work (all I really care about), but I
wonder why.

Thanks,

Dave



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