Convert Video Frames to Images

Question

Mark Jecel Rapir 2018-10-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/423367-convert-video-frames-to-images

编辑： Image Analyst 2021-11-17

Good Day!

I am trying to convert video frames to images and consequently process those images for character recognition. I found the code here and it goes this way

   % Video to Frame Convertion
file=VideoReader(filename);
filename=  (filename);       % to get inforamtaion abt video file
frm_cnt = file.NumberOfFrames;          % No.of frames in the video file
h = waitbar(0,'Please wait...');
font = '.bmp';
for i=1:frm_cnt
    frm(i) = VideoReader(filename,i); % read the Video file
    RGBimg = frame2im(frm(i));  % Convert Frame to image file
    strNmae = num2str(i);
    writeName = strcat(strNmae,font);
    %     imwrite(RGBimg,writeName);
    %figure(1), imshow(RGBimg); % Color Image
    grayImg = rgb2gray(RGBimg); %convert gray
    % figure(2), imshow(grayImg);
    % median filter is applied for smoothing and unwanted noise removal
    grayImg = medfilt2(grayImg,[3 3]);
    %   dynamic thresholding is appiled
    grayImg = adapthisteq(grayImg);
    % figure(3), imshow(grayImg);
c

the error message goes like this

% Error using VideoReader/set Invalid input argument type to 'set'. Type 'help set' for options. Error in VideoReader (line 176) set(obj, varargin{:}); Error in LPRmain (line 69) frm(i) = VideoReader(filename,i); % read the Video file

Can anyone please help me how to remove this error? TIA!

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Answer 1

Image Analyst 2018-10-11

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/423367-convert-video-frames-to-images#answer_340815

编辑：Image Analyst 2021-11-17

ExtractMovieFrames.m

I do that in my attached demo. See how I extract the frames and write them to disk.

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Walter Roberson 2021-11-17

@Aman Swaraj

The lower resolution is a side effect of the method used to insert the frame numbers into the movie. Do you need the frame numbers to be drawn? If not, then there are better ways to write out the frames.

If you do need the frame numbers inserted into the video, then do you have the Computer Vision Toolbox?

Image Analyst 2021-11-17

在 MATLAB Online 中打开

ExtractMovieFrames.m

@Aman Swaraj, Walter's right. If you have the Computer Vision Toolbox, you can use insertText() and then use imwrite() instead of getframe(). That is a very old demo in my original Answer. I have since updated it to use the Computer VIsion Toolbox, if you have it. That newer code is attached. Here are the key lines:

if wantsFrameStamps
    thisFrame = insertText(thisFrame, [5, 5], caption, 'FontSize', 20, 'TextColor', 'yellow', 'BoxColor', 'black'); % Burn text into image
end
imwrite(thisFrame, outputFullFileName) % Original size image