MATLAB: Displaying a difference image as a video

difference imageframesImage Processing Toolboxtrajectoryvideovideo processing

Hello All,
I have a video with 18000 frames in it and also a frame rate of 30 fps and I wrote a small code.
    vidobj = mmreader('myvideo.asf');
    lframe = read(vidobj,Inf);
    numFrames = vidobj.NumberOfFrames;
    vidHeight = vidobj.Height;
    vidWidth = vidobj.Width;
  for k=1:numFrames
  sFrame = rgb2gray(read(vidobj,k);
  if k<numFrames
  pFrame = rgb2gray(read(vidobj,k+1);
  else 
  pFrame = sFrame;
  temp{k} = pFrame - sFrame;
  end
  end
Now what should I do to play all temp{k} (where k=1:numFrames) as a video ? I have tried something like this though I know it's not correct
movie(temp);
But it doesn't work!!!Apart from that, the difference image would be a binary image and I would like to plot row vs column for maximum index (pixel intensity) and display it as a video too. So at the end of my program the user should be able to see three videos 1.My original video. 2.My Difference Video. 3.My row vs column video.
Any help would be sincerely appreciated.

Best Answer

After the loop,
mymovie(1:numFrames).cdata = deal(temp{:});
mymovie(1:numFrames).map = [];
then you can
movie(mymovie)
If you want to write the movie out to disk then if you have 2010b or onwards, consider using the new VideoWriter class. Otherwise,
aviobj = avifile('MyMovie.avi');
aviobj = addframe(aviobj, temp{:});
close(aviobj);
Caution: your sFrame and pFrame are most likely of unsigned integer data type, so when you construct the difference image, the place where the second image is greater than the first would want to go negative but cannot due to the unsigned data type; negatives will be replaced by 0 in that case. That might not be what you want, so you might have to change the data type and rescale the data and then translate and rescale the difference image. There is an Image Processing Toolbox command that will change the data type and rescale for you, but I have forgotten the name of the command.
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