Inserting Color Map value in an image

Question

Rishav 2014-4-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/124426-inserting-color-map-value-in-an-image

评论： Image Analyst 2014-6-10

I have a number of compressed image files in a folder named "Video". I wanted to reconstruct them into an avi video but it said that color map value cannot be non empty. Whats the problem and what is the remedy?

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Answer 1

Marta Salas 2014-4-4

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https://ww2.mathworks.cn/matlabcentral/answers/124426-inserting-color-map-value-in-an-image#answer_132028

编辑：Marta Salas 2014-4-4

在 MATLAB Online 中打开

You can copy the code you are using to be able to help you. You can also try this function:

function make_video(video_dir,extension,aviname,fps)

        resnames=dir(fullfile(video_dir,['*.' extension]));
        aviobj=VideoWriter(aviname);
        aviobj.FrameRate=fps;
        open(aviobj);
        for i=1:length(resnames)
            img=imread(fullfile(video_dirs,resnames(i).name));
            F=im2frame(img);
            if sum(F.cdata(:))==0
                error('black');
            end
            writeVideo(aviobj,F);
        end
        close(aviobj);
end

Example: make_video('/home/user/myImages/','jpg','myvideo.avi',5)

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Rishav 2014-4-4

I appreciate this but can you please give me this code as a stand alone .m file but not within a function? I am a newbie and having problem in function declaration and calling.

Marta Salas 2014-4-4

在 MATLAB Online 中打开

Copy and paste on a .m file

video_dir ='/home/user/myImages/';
extension = 'jpg';
aviname = 'myvideo.avi';
fps =5; 
resnames=dir(fullfile(video_dir,['*.' extension]));
aviobj=VideoWriter(aviname);
aviobj.FrameRate=fps;
open(aviobj);
for i=1:length(resnames)
    img=imread(fullfile(video_dirs,resnames(i).name));
    F=im2frame(img);
    if sum(F.cdata(:))==0
        error('black');
    end
    writeVideo(aviobj,F);
end
close(aviobj);

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Answer 2

Rishav 2014-4-4

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https://ww2.mathworks.cn/matlabcentral/answers/124426-inserting-color-map-value-in-an-image#answer_132107

I am working on Matlab 2010a and the videoWriter function doesnt work. Getting the error ??? Undefined function or method 'VideoWriter' for input arguments of type 'char'.

Error in ==> Formation2 at 7 aviobj=VideoWriter(aviname); So any solutions??

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Image Analyst 2014-6-10

Rishav, why is it taking you so long to resolve this? What's the problem now?

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Answer 3

Rishav 2014-4-5

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https://ww2.mathworks.cn/matlabcentral/answers/124426-inserting-color-map-value-in-an-image#answer_132279

Used the previous code but still getting the error of "non Empty color map". Any Solution?

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Image Analyst 2014-4-5

That's because it's not right. See my answer for how to do it. You will notice differences where the colormap is concerned.

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Answer 4

Image Analyst 2014-4-5

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https://ww2.mathworks.cn/matlabcentral/answers/124426-inserting-color-map-value-in-an-image#answer_132280

ExtractMovieAVIFrames.m

See my attached example. It first reads a video and writes out all the frames to disk. In the second part it reconstructs the video by reading in all those images from disk and building a movie from them. It's very well commented so even new people like yourself are able to follow it.