How to count the frequency of flashing light in a video

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Hi, I have a video-file, rgb, format avi, dimension 62x62, rate 60fps. duration 1min. The event is a flashing red light otherwise dark.
The flashing frequency very from video to video. So I wonder if someone could suggest me how to count the frequency using image-processing or video-processing tool box.
Thank you in advance for your attention
Emerson
  1 Comment
Luke Abellanosa
Luke Abellanosa on 4 Feb 2021
hello emerson were you able to get the exact value of the frequency??

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Accepted Answer

Star Strider
Star Strider on 30 Apr 2015
Cedric Wannaz posted this code to do just that about a year ago. You can probably adapt it to your application.
  5 Comments
Luke Abellanosa
Luke Abellanosa on 4 Feb 2021
hello again can i ask if what are to be edited in this script depending on the properties of the video im still a beginner to this
vidObj = VideoReader( '1.avi' ) ;
nFrames = vidObj.NumberOfFrames ;
tFrame = (1:nFrames) / vidObj.FrameRate ;
ghostCom = zeros( nFrames, 1 ) ;
for fId = 1 : nFrames
grayImage = rgb2gray( read( vidObj, fId )) ;
ghostCom(fId) = sum( grayImage(:) ) ;
end
figure() ; clf ;
set( gcf, 'Color', 'White', 'Units', 'Normalized', ...
'OuterPosition', [0, 0.1, 1, 0.6] ) ;
plot( tFrame, ghostCom/max(ghostCom), 'b' ) ;
set( gca, 'YTick', [0, 1] ) ;
xlabel( 'Time [s]' ) ;
[r] =risetime(ghostCom);
FREQUENCY =numel(r)/60;

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