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Posted by Pat Horridge on 06/20/06 11:15
"Richard Crowley" <richard.7.crowley@intel.com> wrote in message
news:e6rs2e$dv5$1@news01.intel.com...
> "Jeff_BTFP" wrote ...
>>I do concert video (projection/to tape), and had a question regarding
>> an effect I saw on TV last night, and what it's benefits are.
>>
>> The show used a lot of moving lights, and I noticed in certain
>> situations when the moving light was pointed directly at the camera, a
>> black spot would appear in the middle of the light source (lamp). I
>> interpret this as some kind of a Luma Key.
>
> Not necessarily. It could be an artifact of the camera pickup
> device, or the circuitry anywhere along the line. Sometimes if
> something is TOO bright (like the very center of a light aimed
> directly at the camera, the brightness "folds back on itself"
> and appears to be black. Or sometimes this shows up as a
> vertical streak (black or white) from the bright spot all the
> way to the top of the picture, and all the way to the bottom.
>
>> What are the benefits of using this? Is this just some piece of
>> hardware the network puts in place to make sure that the video is
>> broadcast safe??
>
> Dunno of any "benefits"? In fact it can be rather dangerous in
> terms of the camera pickup device (tube/solid-state sensor).
> For the same reason you shouldn't look at the sun, etc.
>
>> As you can tell, I know very little about TV Broadcast....If you could
>> help me out or point me to a website that goes more in depth, I'd
>> appreciate it greatly.
>
> Not sure exactly what you are asking?
Very unlikely to be an incamera issue as this would be a big problem.
Not a CCD issue as Richard said overload would give vertical lines.
I suspect there was some post digital processing that was overloaded.
If the digital word is too big there is a danger of the most significant bit
being lost and making the resultant value very small.
I'd supect a bit of downstream processing and not a very well built bit of
kit at that.
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