red color tracking

Hi Sir, this code is create for tracking the red color of the video, however, there is a error when i run the code, Can you please help me to solve the problem and let me know the fault? thank you.

here is my code.

    movieInfo = aviinfo('barbeq');
  mov = aviread('barbeq') ;

        numberOfFrames = size(mov, 2);
  numberOfFramesWritten = 0;
  % Prepare a figure to show the images in the upper half of the screen.

      for f = 1 : numberOfFrames
      % Extract the frame from the movie structure.
      thisFrame = mov(f).cdata;

           
      end
     %imshow(thisFrame)
nrames=f;
for b = 2:nrames

     % from the grayscale image to extract the red components in the image.
    diff_im = imsubtract(thisFrame, rgb2gray(b));

    %Use a median filter to filter out noise
    diff_im = medfilt2(diff_im, [3 3]);

     % Convert the resulting grayscale image into a binary image.
    diff_im = im2bw(diff_im,0.18);
    bw = bwlabel(diff_im, 8);
     stats = regionprops(bw, 'BoundingBox', 'Centroid');
     imshow(thisFrame)
end

when I run this code, it gave me the feedback.

??? Error using ==> rgb2gray>parse_inputs at 82 MAP must be a m x 3 array.

Error in ==> rgb2gray at 35 X = parse_inputs(varargin{:});

Error in ==> colortest at 26

Can someone please help me in this part? Thank you very much...

Answer 1

[Walter Roberson]

Your "for f" loop extracts all the frames, overwriting the single matrix "thisFrame" each time, leaving "thisFrame" just as the last frame. That is unlikely to be what you want.

You are passing "b" to rgb2gray(). "b" is your scalar variable from the "for b" loop. You cannot rgb2gray() as scalar variable.

[Ernest]

By the way, can i ask, is it possible to write a code to tracking a color object by using image processing toolbox?

[Walter Roberson]

I think that Image Analyst has a demo for that.

[Image Analyst]

I have some color segmentation demos in my File Exchange but I haven't posted anything that tracks across video frames. There are some in the File Exchange, but I give no gaurantees about how good they are:

http://www.mathworks.com/matlabcentral/fileexchange/33666-simple-particle-filter-demo

http://www.mathworks.com/matlabcentral/fileexchange/35353-tacking-a-maroon-colour-ball-in-video

http://www.mathworks.com/matlabcentral/fileexchange/34498-skinfacedetecting

http://www.mathworks.com/matlabcentral/fileexchange/33804-tracking-of-a-point-in-video-using-kalman-filter

http://www.mathworks.com/matlabcentral/fileexchange/32492-laser-dot-isolation

and so on. 305 File Exchange items on tracking!

[Ernest]

Do you have any code that can tracking a color object in a avi video file? but not using webcam?