Re: Video images of people in Performer

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Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Wed, 20 Sep 1995 11:24:52 -0600

On Sep 20, 2:20pm, Kim Michael Fairchild wrote:
> Subject: RE: Video images of people in Performer
> Hi,
>
> >>
> >> Hi,
> >>
> >> We are about the same thing in a quite simple way - just take an image
> >> of the background WITHOUT the talking head and store it in memory. Then
> >> in each frame we compare the backgroung with the current frame and the
> >> head is where we find a significant difference. This is simple to
implement
> >> and works not-too-badly. It requires a static backgroung, i.e. if a
> >> colegue is working behind you in the camera field of view it won't work.
> >>
> >> Hope this helps,
> >> Igor
> >>
>
> Sorry, I think I didn't state the problem clearly in the first
> message.
>
> This is the same approach that we tried. Our problem seems to be that
> 1) the indy camera is terrible, the iris is so small we have to light
> the person to get it to work.

Lighting the subject isn't unusual practice. If the camera isn't good
enough for what you want to do you could try connecting a better camera
to the composite or S-video input at the rear of the box and select an
analog source using the video control panel.

>
> 2) the Indy seems to "pulse", the values aren't stable and so we get
> problems like the dark hair of people fading in and out of the
> background.

>From the video control panel select IndyCam->SignalControls, and select
a different shutter speed. Also turn off AGC Enable (automatic gain control)
this should eliminate any pulsing.

>
> Do you do any cleanup algorithm to look for isolated pixels?
>
> What machine do you use, Indy or PC? Love to share code.
>
> thanks, Kim.
>
>
>
>-- End of excerpt from Kim Michael Fairchild

-- 
Angus Dorbie,
Silicon Graphics Ltd, UK
dorbie++at++reading.sgi.com

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