How can I save individual movie frames from a video?

I want to save individual frames of my video--how can I do this?

I tried the code below but it is not working...

clc
close all
clear all

source='Intellegent.avi';

vidobj=VideoReader(source);

frames=vidobj.Numberofframes;

for f=1:frames
    thisframe=read(vidobj,f);
    figure(1);imagesc(thisframe);
    for K=1:size(thisframe,3)
        itframe=thisframe(:,:,K);
        thisfile = sprintf('frame_%04d.jpg', K);
        imwrite( thisframe, thisfile );
    end
end

[Sean de Wolski]

What "isn't working" about it? Do you get an error? Do the files nto appear? Do they appear corrupted?

[Muluken Birara]

how to extract image frames form given video file with different number of frame size(like 2 frame per second , 10 FPS

[Walter Roberson]

The demo given by Image Analyst does not need to care what the frame rate was of the original video in order to extract all of the frames into files.

Answer 1

[Image Analyst]

Here's a complete working demo for you:

% Demo macro to extract frames and get frame means from an avi movie
% and save individual frames to separate image files.
% Also computes the mean gray value of the color channels.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
fontSize = 14;

% Open the rhino.avi demo movie that ships with MATLAB.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
movieFullFileName = fullfile(folder, 'rhinos.avi');
% Check to see that it exists.
if ~exist(movieFullFileName, 'file')
  strErrorMessage = sprintf('File not found:\n%s\nYou can choose a new one, or cancel', movieFullFileName);
  response = questdlg(strErrorMessage, 'File not found', 'OK - choose a new movie.', 'Cancel', 'OK - choose a new movie.');
  if strcmpi(response, 'OK - choose a new movie.')
    [baseFileName, folderName, FilterIndex] = uigetfile('*.avi');
    if ~isequal(baseFileName, 0)
      movieFullFileName = fullfile(folderName, baseFileName);
    else
      return;
    end
  else
    return;
  end
end

try
  videoObject = VideoReader(movieFullFileName)
  % Determine how many frames there are.
  numberOfFrames = videoObject.NumberOfFrames;
  vidHeight = videoObject.Height;
  vidWidth = videoObject.Width;

  numberOfFramesWritten = 0;
  % Prepare a figure to show the images in the upper half of the screen.
  figure;
%   screenSize = get(0, 'ScreenSize');
  % Enlarge figure to full screen.
  set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
  
    % Ask user if they want to write the individual frames out to disk.
    promptMessage = sprintf('Do you want to save the individual frames out to individual disk files?');
    button = questdlg(promptMessage, 'Save individual frames?', 'Yes', 'No', 'Yes');
    if strcmp(button, 'Yes')
        writeToDisk = true;

          % Extract out the various parts of the filename.
          [folder, baseFileName, extentions] = fileparts(movieFullFileName);
          % Make up a special new output subfolder for all the separate
          % movie frames that we're going to extract and save to disk.
          % (Don't worry - windows can handle forward slashes in the folder name.)
          folder = pwd;   % Make it a subfolder of the folder where this m-file lives.
          outputFolder = sprintf('%s/Movie Frames from %s', folder, baseFileName);
          % Create the folder if it doesn't exist already.
          if ~exist(outputFolder, 'dir')
              mkdir(outputFolder);
          end
      else
          writeToDisk = false;        
      end

      % Loop through the movie, writing all frames out.
    % Each frame will be in a separate file with unique name.
    meanGrayLevels = zeros(numberOfFrames, 1);
    meanRedLevels = zeros(numberOfFrames, 1);
    meanGreenLevels = zeros(numberOfFrames, 1);
    meanBlueLevels = zeros(numberOfFrames, 1);
      for frame = 1 : numberOfFrames
      % Extract the frame from the movie structure.
      thisFrame = read(videoObject, frame);
      
          % Display it
          hImage = subplot(2, 2, 1);
          image(thisFrame);
          caption = sprintf('Frame %4d of %d.', frame, numberOfFrames);
          title(caption, 'FontSize', fontSize);
          drawnow; % Force it to refresh the window.    

    % Write the image array to the output file, if requested.
        if writeToDisk
             % Construct an output image file name.
            outputBaseFileName = sprintf('Frame %4.4d.png', frame);
            outputFullFileName = fullfile(outputFolder, outputBaseFileName);

              % Stamp the name and frame number onto the image.
              % At this point it's just going into the overlay, 
              % not actually getting written into the pixel values.
              text(5, 15, outputBaseFileName, 'FontSize', 20);

              % Extract the image with the text "burned into" it.
              frameWithText = getframe(gca);
              % frameWithText.cdata is the image with the text
              % actually written into the pixel values.
              % Write it out to disk.
              imwrite(frameWithText.cdata, outputFullFileName, 'png');
          end

    % Calculate the mean gray level.
    grayImage = rgb2gray(thisFrame);
    meanGrayLevels(frame) = mean(grayImage(:));

    % Calculate the mean R, G, and B levels.
    meanRedLevels(frame) = mean(mean(thisFrame(:, :, 1)));
    meanGreenLevels(frame) = mean(mean(thisFrame(:, :, 2)));
    meanBlueLevels(frame) = mean(mean(thisFrame(:, :, 3)));

    % Plot the mean gray levels.
    hPlot = subplot(2, 2, 2);
        hold off;
    plot(meanGrayLevels, 'k-', 'LineWidth', 2);
        hold on;
        plot(meanRedLevels, 'r-');
        plot(meanGreenLevels, 'g-');
        plot(meanBlueLevels, 'b-');
        grid on;
    
        % Put title back because plot() erases the existing title.
    title('Mean Gray Levels', 'FontSize', fontSize);
        if frame == 1
      xlabel('Frame Number');
      ylabel('Gray Level');
            % Get size data later for preallocation if we read
            % the movie back in from disk.
            [rows columns numberOfColorChannels] = size(thisFrame);
        end

          % Update user with the progress.  Display in the command window.
          if writeToDisk
          progressIndication = sprintf('Wrote frame %4d of %d.', frame, numberOfFrames);
          else
          progressIndication = sprintf('Processed frame %4d of %d.', frame, numberOfFrames);
          end
      disp(progressIndication);
      % Increment frame count (should eventually = numberOfFrames
      % unless an error happens).
      numberOfFramesWritten = numberOfFramesWritten + 1;
      
      % Now let's do the differencing
      alpha = 0.5;
      if frame == 1
        Background = thisFrame;
      else
        % Change background slightly at each frame
  %       Background(t+1)=(1-alpha)*I+alpha*Background
        Background = (1-alpha)* thisFrame + alpha * Background;
      end
      % Display the changing/adapting background.
      subplot(2, 2, 3);
      imshow(Background);
      title('Adaptive Background', 'FontSize', fontSize);
      % Calculate a difference between this frame and the background.
      differenceImage = thisFrame - uint8(Background);
      % Threshold with Otsu method.
      grayImage = rgb2gray(differenceImage); % Convert to gray level
      thresholdLevel = graythresh(grayImage); % Get threshold.
      binaryImage = im2bw( grayImage, thresholdLevel); % Do the binarization
      % Plot the binary image.
      subplot(2, 2, 4);
      imshow(binaryImage);
      title('Binarized Difference Image', 'FontSize', fontSize);
      end

      % Alert user that we're done.
      if writeToDisk
          finishedMessage = sprintf('Done!  It wrote %d frames to folder\n"%s"', numberOfFramesWritten, outputFolder);
      else
          finishedMessage = sprintf('Done!  It processed %d frames of\n"%s"', numberOfFramesWritten, movieFullFileName);
      end
      disp(finishedMessage); % Write to command window.
      uiwait(msgbox(finishedMessage)); % Also pop up a message box.

      % Exit if they didn't write any individual frames out to disk.
      if ~writeToDisk
          return;
      end

      % Ask user if they want to read the individual frames from the disk,
      % that they just wrote out, back into a movie and display it.
      promptMessage = sprintf('Do you want to recall the individual frames\nback from disk into a movie?\n(This will take several seconds.)');
      button = questdlg(promptMessage, 'Recall Movie?', 'Yes', 'No', 'Yes');
      if strcmp(button, 'No')
          return;
      end

      % Read the frames back in, and convert them to a movie.
      % I don't know of any way to preallocate recalledMovie.
      for frame = 1 : numberOfFrames
          % Construct an output image file name.
          outputBaseFileName = sprintf('Frame %4.4d.png', frame);
          outputFullFileName = fullfile(outputFolder, outputBaseFileName);
          % Read the image in from disk.
          thisFrame = imread(outputFullFileName);
          % Convert the image into a "movie frame" structure.
          recalledMovie(frame) = im2frame(thisFrame);
      end
      % Get rid of old image and plot.
      delete(hImage);
      delete(hPlot);
      % Create new axes for our movie.
      subPlot(1, 3, 2);
      axis off;  % Turn off axes numbers.
      title('Movie recalled from disk', 'FontSize', fontSize);
      % Play the movie in the axes.
      movie(recalledMovie);
      % Note: if you want to display graphics or text in the overlay
      % as the movie plays back then you need to do it like I did at first
      % (at the top of this file where you extract and imshow a frame at a time.)
      msgbox('Done with this demo!');

catch ME
  % Some error happened if you get here.
  stError = lasterror;
  strErrorMessage = sprintf('Error extracting movie frames from:\n\n%s\n\nError: %s\n\n)', movieFullFileName, stError.message);
  uiwait(msgbox(strErrorMessage));
end

[Algorithms Analyst]

Ohhh.this very long.I cannot read it to separate it for me.Kindly share a short one only to record frames I dont need graymean and other stuf.because I want to save individual resultsant frames..

[Sheece Gardezi]

yes too long !!

[Image Analyst]

What are you looking for? The key line is the call to imwrite(). If you can't figure out which lines to delete then maybe I can.

[Nahiduddin Mohammad Musa]

I tried witha different avi file in MATLAB 2011 but this message shows up:

'Error extracting movie frames from:

C:\Users\Nahiduddin\Downloads\adr1.avi

Error: Access is denied.

)'

[Image Analyst]

Step through it line by line and see where the error gets thrown. Chances are you're trying to write to a folder where you're not allowed to, like somewhere under the "Program Files" folder.

[Nahiduddin Mohammad Musa]

Thank you very much @Image Analyst.I could sort out the problem.It was really permission issues in my PC

Answer 2

[Willy]

clc
close all
clear all
source='/Users/zzzz/Desktop/FILE1739.mov';
vidobj=VideoReader(source);
frames=vidobj.Numberofframes;
for f=1:frames
  thisframe=read(vidobj,f);
  figure(1);imagesc(thisframe);
  thisfile=sprintf('/Users/zzzz/Desktop/FILE1739/frame_%04d.jpg',f);
  imwrite(thisframe,thisfile);
end

Does what you asked, did not polish your code further ;-)

Answer 3

[Ali Noori]

I have attached a code to convert movie to frames sequences and store them in folder name "aliiiii". Just you need to create the folder name "aliiiii" in matlab directory. Cheers

[Ashfaq Ahmed]

Where is attached code "aliiiii"?