[opendtv] Re: RGB mania
- From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 18 Jan 2005 19:28:08 -0000
Thanks Peter, that's a correct interpretation of the history. Perhaps it
will dispel some of the myth-making.
----- Original Message -----
From: "Peter Fasciano" <Peter_Fasciano@xxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>; "Allen Le Roy Limberg" <allimberg@xxxxxxxxxxxx>
Sent: Tuesday, January 18, 2005 6:37 PM
Subject: [opendtv] Re: RGB mania
> A very short history of Gamma in video.
>
> In 1936 the BBC was the first organization to deploy a clear gamma =
> strategy in broadcasting. They first applied a gamma amplifier located =
> after the video switcher. All camera outputs and all monitoring scopes =
> worked with the raw video signal from the emitron tube cameras (similar =
> to iconoscope design) which had a 1:1 output signal correlation to the =
> light input. =20
>
> Within the first year of operation the BBC radically modified their =
> gamma deployment strategy. They removed the special gamma amplifier =
> from the switcher (vision mixer) output and relocated the gamma circuit =
> to the video amplifiers in their emitron cameras. =20
>
> What they knew at the start:
> The gamma circuit corrected the camera output to correspond to the =
> response characteristic of the CRT control grid design.
> When the video signal is converted from its raw form to the gamma =
> modified form (approx .45) the atmospheric noise of the OTA transmission =
> becomes evenly distributed across the luminance range. =20
>
> What they gained by moving the gamma function to the camera.
> The monitoring scopes provided a representation of the camera output =
> signal that was much easier to interpret. =20
> Camera shading/matching became easier to accommodate with the improved =
> signal monitoring.
> The vision mixer function was improved as the signals could now be =
> "linearly" blended with faders. =20
>
> Much of this development work is attributed to Alan Blumlein who was the =
> tech lead at the London Station.
>
>
> Pete Fasciano =20
> Fellow, Advance Development =20
> Co-founder, Avid Technology =20
> 1925 Andover St. B2-3 =20
> Tewksbury, MA 01876 =20
> Ext: 978-640-3308
> Fax: 978-640-3116
> peter_fasciano@xxxxxxxx
>
>
> -----Original Message-----
> From: Henry Baker [mailto:hbaker1@xxxxxxxxxxxx]
> Sent: Tuesday, January 18, 2005 12:47 PM
> To: Allen Le Roy Limberg
> Cc: opendtv@xxxxxxxxxxxxx
>
>
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