Error Concealment | JPEG | MPEG-4 | Wavelet | YUV

Hello everyone,

I'm working on image/video processingin matlab. I've encountered a problem, a simple one
indeed, but troublesome, .. below I'm pasting a code which is simply read an avi file and the
I'm just converting the frames to images and then I'm throwing away alternating rows, which
reduces my image. the problem is that it gets replicated .... why??

your helpwill be apprecaited ..thank you in advance
regards
Ahmad

close all;
clear all;
% file that we are gonna read
my_movie_info = aviinfo('redcup.avi');
my_movie_info.Filename;
my_movie_info.FileSize;
my_movie_info.FileModDate;
my_movie_info.NumFrames;
my_movie_info.FramesPerSecond;
my_movie_info.Width;       
my_movie_info.Height;      
my_movie_info.ImageType;   
my_movie_info.VideoCompression;  
my_movie_info.Quality;           
my_movie_info.NumColormapEntries; 

%**********************************************************************************************
***********************************
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%reading the avi file frame by
frame%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%declare array
M_Array=[];
% reading one frame at a time and storing it in to array
for i=1:my_movie_info.NumFrames;
        mov=aviread('redcup.avi',i);
        M_Array=[M_Array mov];       
end

%**********************************************************************************************
***********************************
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Converting frames in to image for
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%processing
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure;
R_Array=[];
for j=1:my_movie_info.NumFrames

        map=[0 255];
        %montage(image,map);%displays the images in new figure
        [image,map]=frame2im(M_Array(j));
%         mask=fspecial('log');
%         I=imfilter(image,mask);
        
        [r c]=size(image);
        I=zeros(r/2,c);

        p=1;

        for m=1:2:r
            for n=1:c
                I(p,n)=image(m,n);
             end
            p=p+1;
        end

        %R_Array=[im2frame(I,map)];
        %movie(R_Array)       
        montage(I,map)
        
end

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Thanks buddies,

the problem of reducing the frame size to half has been solved. now I'm getting the following
problm, the reduced size of the frames cannot by converted back to movie frames
(R_Array=[R_Array im2frame(I,map)]) .. 

it gives the error that .... colormap cannot be empty .. and I don't know why is the (map
variable empty) .... help will be appreciated 
regards
Ahmad

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
R_Array=[];
for j=1:my_movie_info.NumFrames
        
        %montage(image,map);%displays the images in new figure
        [image,map]=frame2im(M_Array(j));
        
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %%%%%%%%%%%%% reducing the width of the frames by half %%%%%%%%%%%
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

        I=zeros(my_movie_info.Height/2,my_movie_info.Width/2);      
        p=1;
        for s=1:2:my_movie_info.Height   
            q=1;
            for t=1:2:my_movie_info.Width
                I(p,q)=image(s,t);
                q=q+1;
            end
            p=p+1;
        end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%           mask=fspecial('log');
%           Im=imfilter(I,mask);       

         R_Array=[R_Array im2frame(image,map)];
         %montage(I,map)
      end

movie(R_Array)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

error: the colormap cannot be empty

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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