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Thread View: sci.image.processing
2 messages
2 total messages Started by Joe Latone Thu, 30 Jul 1992 21:30
Video/Image Processing Problem (Non-fictional)
#250
Author: Joe Latone
Date: Thu, 30 Jul 1992 21:30
51 lines
2903 bytes
Hi,

I need some help with a video/image processing application I'm working
with and thought that if I described the problem I'm currently having,
someone might recognize it and suggest a peice of hardware that might
resolve it.

The system is set up as follows (I'll try not to misuse the terminology
and try to be as specific as I can):  A CCD video camera(1) is focused
on a 70 foot-wide area of a baseball field from about 100 feet away and
the object of interest is -- you guessed it -- a baseball.  The video
output from the camera feeds into a digital AV mixer(2) for reasons
which are not of interest here.  The output from the mixer feeds into a
NTSC->RGB converter, which in turn feeds the green and sync into a
PC-based image processing board(3), which digitizes the green signal
into 8 bits/pixel.  One other thing I should let you know is that the
camera is connected to the various video equipment I mentioned by
several hundred feet (approx. 500) of professional quality coax cable.

The purpose of the system is to try to find and track a baseball
automatically by digitizing and processing the video as fast as
possible.

The problem with the system is trying to deal with the various natural
lighting conditions and backgrounds, combinations of which cause the
white ball to get lost in the dark dirt/grass background by the time
the video signal is digitized and processed.  I need a way to maximize
the "brightness/whiteness" of the ball and maximize the
"blackness/darkness" of the sand/grass.  This seems like a fairly
well-contained problem (i.e., the ball is always very white and the
background is always either green or light brown and the lighting
conditions are either early-afternoon natural light or major league
stadium lighting) and one that an additional piece of video processing
hardware or camera filters might be able to solve for me.

Any help would be appreciated.  Hardware specifics are listed below and
I included prices to give you an idea of the quality of the equipment.

Regards, Joe

#include <std/disclaimer>
The information in this posting has nothing to do with my employer, IDE --
it's strictly related to my own computing hobby.

(1) The camera is from a company called Vicom and is a "high-resolution
black and white" video camera.  For what it's worth, it's also a 
"3-chip implementation."  The camera body costs about $1000.

(2) A Panasonic Digital AV Mixer which cosst about $2000.

(3) A Matrox MVP-AT 640 image processing board which costs about $5000.
Re: Video/Image Processing Problem (Non-fictional)
#82
Author: David Kastrup
Date: Sun, 02 Aug 1992 07:13
24 lines
1780 bytes
latone@trixie.ide.com (Joe Latone) writes:


>The purpose of the system is to try to find and track a baseball
>automatically by digitizing and processing the video as fast as
>possible.

>The problem with the system is trying to deal with the various natural
>lighting conditions and backgrounds, combinations of which cause the
>white ball to get lost in the dark dirt/grass background by the time
>the video signal is digitized and processed.  I need a way to maximize
>the "brightness/whiteness" of the ball and maximize the

Sounds like a background subtraction problem to me. Just subtract a
short-time average (5 secs should be ok) from your current data.
Unless the ball is stopping on the field (and you can detect that),
this should yoield good contrast. Of course the camera would have to be
mounted. Since the ball will be more or less of the same size in
the picture, you can use a matched filter on the bckground subtracted
data. This is, for every point integrate a ball-shaped surrounding
area. The highest integral (if your ball's bright) wins.
Thirdly, maybe using only the green data is not too good an idea.
If your filed is brown, the blue data, or even more so, all data
should be better.
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