MATLAB: Hi! Would you please help me :] the db.mat only save the last input image value. this don’t give multiple images input values.

help

    %%Module Training
    clc;
    clear all;
    close all;
    [fname path]=uigetfile('.jpg','Open a Face as input for Training');
    fname=strcat(path,fname);
    img=imread(fname);
    imshow(img);
    %%drawnow;
    title('Input Face');
    c=input('Enter the Class ');
    %%Feature Extraction
    F = FeatureStatistical(img);
    try
        S = load('db.mat');
        F=[F c];
        db=[db;F];
        save db.mat db
    catch
        F=reshape(F,[3,2]);
        F=reshape(F,[1,6]);
        db=[F c];
        save db.mat db
    end
    %%FeatureStatistical
    function [F]= FeatureStatistical(img)
    img=double(img);
    mn=mean(mean(img));
    sd=std(std(img));
    F=[mn sd];
    %%FaceClassifier
    clc;
    clear all;
    close all;
    [fname path]=uigetfile('.jpg','Provide a Face for Testing');
    fname=strcat(path,fname);
    img=imread(fname);
    imshow(img);
    title('Test Face');
    Ftest = FeatureStatistical(img);
    load db.mat
    Ftrain=db(:,1:2);
    Ctrain=db(:,7);
    for(i=1:size(Ftrain,1))
    dist(i,:)=sum(abs(Ftrain(i,:)-Ftest));
    end
    Min=min(dist);
    if(Min<3)
    m=find(dist==Min,1);
    det_class=Ctrain(m);
    msgbox(strcat('Detected Class= ',num2str(det_class)));
    else
      msgbox('Not Same');
    end

Best Answer

Your question concerned the saving of data. I find the save command here:
try
  S = load('db.mat');
  F=[F c];
  db=[db;F];
  save db.mat db
catch
  F=reshape(F,[3,2]);
  F=reshape(F,[1,6]);
  db=[F c];
  save db.mat db
end
Now we cannot guess what happens, and the code suppressed the output of explanations also. What a pity. Prefer to display a message, if you catch an error:
 try
    S = load('db.mat');
    F=[F c];
    db=[db; F, c];
  catch ME
    disp(ME.message);
    % F  = reshape(F,[3,2]);  % Omit the duplicate reshaping - it has no effect
    F  = reshape(F, [1,6]);
    db = [F c];
  end
  save('db.mat', 'db');
So what do you see? Perhaps the file "db.mat" is not found in the current folder. Then provide a path.
Some hints:
  • "db.mat only save the last input image value" is not clear. Where do you expect the code to behave differently?
  • It is a mystery for me, why so many users include this evil brute clearing header in the code: clc;clear all;close all; Especially the clear all is bad, because it deletes all loaded functions from the memory. Reloading from the disk is slow and a waste of energy.
  • Do not shadow the important built-in function "path" by a local variable. This can cause strange results during debugging.
  • Use fullfile instead of strcat to create a file name.
  • While mean(mean(X)) is a valid method to calculate the total mean value as in mean(X(:)), this does not work for std. Are you sure that you want to get the standard deviation over the the standard deviations of the columns of X? I assume std(std(img)) is not what you want.
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