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From: Vikas Bajpai on 18 Apr 2010 16:31
I have a video with 300 frames but i want to extract first two and the
100th frame from that video sequence.Please help me with the code.
From: ImageAnalyst on 18 Apr 2010 16:35
On Apr 18, 4:31 pm, Vikas Bajpai <vikas.bajpa...(a)gmail.com> wrote:
> I have a video with 300 frames but i want to extract first two and the
> 100th frame from that video sequence.Please help me with the code.

--------------------------------------------
Review this demo and you'll be able to figure it out.
Be sure to join any lines split into two by the newsreader.


% Demo macro to extract frames from an avi movie to separate files.
% by ImageAnalyst
clc;
close all;
% Open the rhino.avi demo movie that ships with MATLAB.
movieFullFileName = 'C:\Program Files\MATLAB\R2010a\toolbox\images
\imdemos\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
mov = aviread(movieFullFileName);
% movie(mov);
% Make a special output folder to hold all the separate movie frames
% as their own image files.
outputFolder = fullfile(cd, 'Rhino Movie');
if ~exist(outputFolder, 'dir')
mkdir(outputFolder);
end
% Determine how many frames there are.
numberOfFrames = size(mov, 2);
numberOfFramesWritten = 0;
% Prepare a figure to show the images.
figure;
screenSize = get(0, 'ScreenSize');
newWindowPosition = [1 1 screenSize(3)/2 screenSize(4)/2];
set(gcf, 'Position', newWindowPosition); % Maximize figure.
% Loop through the movie, writing all frames out.
% Each frame will be in a separate file with unique name.
for frame = 1 : numberOfFrames
% Extract the frame from the movie structure.
thisFrame = mov(frame).cdata;
% Display it
image(thisFrame);
drawnow; % Force it to refresh the window.
% Construct an output iamge file name.
outputBaseFileName = sprintf('Frame %4.4d.png', frame);
outputFullFileName = fullfile(outputFolder, outputBaseFileName);
% Write the image array to the output file.
imwrite(thisFrame, outputFullFileName, 'png');
% Update user with the progress. Display in the command window.
progressIndication = sprintf('Wrote frame %4d of %d.', frame,
numberOfFrames);
disp(progressIndication);
% Increment frame count (should eventually = numberOfFrames
% unless an error happens).
numberOfFramesWritten = numberOfFramesWritten + 1;
end
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);
msgboxw(strErrorMessage);
end
% Alert user that we're done.
finishedMessage = sprintf('Done! It wrote %d frames to folder\n"%s"',
numberOfFramesWritten, outputFolder);
disp(finishedMessage); % Write to command window.
msgbox(finishedMessage); % Also pop up a message box.

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