[opendtv] Re: RGB mania

  • From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Sun, 16 Jan 2005 17:06:15 -0000

Have you any idea how hard analogue circuit design is? You're asking for
video amplifiers with at least 75MHz bandwidth and over 90dB SNR. The Sony
HDW900 has 12-bit adcs and achieves about 58dB, but that circuitry consumes
about 20% of total power in the camera. Dropping from 12- to 10-bit in the
750 is virtually the only reason why its power consumption is lower.
Astronomical cameras achieve that sort of performance by using very long
exposure periods and liquid gas cooling, neither is appropriate for shooting
real life.

----- Original Message ----- 
From: "Craig Birkmaier" <craig@xxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Sunday, January 16, 2005 3:55 PM
Subject: [opendtv] Re: RGB mania


> At 9:17 AM -0600 1/16/05, Doug McDonald wrote:
> >
> >They could if designed right. The solid state sensors used
> >are vastly and absolutely in every way superior to film,
> >except raw pixel count. They have enormous dynamic range,
> >usually in the 16 bit range, 60000:1, if there is
> >enough light (outdoors, for example). You are not going to
> >get full use of that of course without getting all the bits
> >out of the camera and into storage somewhere, or at least
> >close (e.g. store the 0.8 or 0.9 power of the data.)
> >
>
> Yup...
>
> But we are stubbornly clinging to an archaic view of how video should
> be captured, encoded and processed. Probably has something to do with
> the fact that some companies want to recoup past investments...
>
>
> >
> >
> >>
> >>  Everyone should have a copy of Joe Kane's Video Essentials, so that
> >>  they can learn how to properly calibrate their displays to maximize
> >>  the perception of the full dynamic range.
> >
> >That disk is the single worst cause of lost detail in home
> >video. It sets the black level too low, resulting in
> >mush lost detail in the blacks.
>
> I know Joe Kane sir and you are NO Joe Kane.
>
> And you are wrong.
>
> >You set the blackest black well up on the toe if
> >you want details in the blacks. If you don't, by definition
> >you lose detail in the blacks! I'm not saying you have to set
> >it up above the toe into the linear gamma region, of course.
> >But if you want detail in the blacks (Zone 1) you MUST get them
> >well up onto the toe. As I said, I have never seen a movie with
> >detail in Zone 1. Stills, in photo art galleries, yes, they are
> >a "dime a dozen". Movies, no.
> >
>
> I think you are out of your league here Doug.
>
> What gamma are you talking about? There is no gamma in film negative,
> although there are both linear and non-linear ranges for negative
> density in the normal response curve. If you set the blackest black
> at the point where the density response turns linear, you have thrown
> away all of the potential for detail in the blacks.
>
> Gamma is a uniquely video/display concept. Among other things, it is
> an attempt to modify the response of the system to improve the
> dynamic range of a system that is inadequate.
>
> Regards
> Craig
>
>
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