How to Save image Features in .mat file??

Question

saeeda saher 2018-4-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397679-how-to-save-image-features-in-mat-file

评论： Ameer Hamza 2018-4-30

I am trying to extract facial features from image using HOG and trying to save them in .mat file, but when i run my code it saves the features of all images in one column. I want to save the features of each image in separate row.

Here is my CODE:

myFolder = 'folder'; % or whatever.
if ~isdir(myFolder)
  errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
  uiwait(warndlg(errorMessage));
  return;
end
filePattern = fullfile(myFolder, '*.jpg');
matFiles = dir(filePattern);
for k = 1:length(matFiles)
  baseFileName = matFiles(k).name;
  img = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', img);
  storedStructure = imread(img);
  % Now do whatever you need to do with the structure you recalled.
  %figure    % New figure, do not specify the index
  %imshow(img);
  FaceDetect = vision.CascadeObjectDetector;
  FaceDetect.MergeThreshold = 7 ;
  BB = step(FaceDetect,storedStructure); %figure(2),imshow(img);
  for i = 1:size(BB,1)
     rectangle('Position',BB(i,:),'LineWidth',3,'LineStyle','- ','EdgeColor','r');
  end
  % figure
    for i = 1:size(BB,1)
      J= imcrop(storedStructure,BB(i,:));
      %subplot(6,6,i);
      figure
      imshow(J);
      % Create a folder with the base file name
      [~, baseFileNameNoExt, ~] = fileparts(baseFileName);
      outputFolder = fullfile(myFolder, baseFileNameNoExt);
      if ~exist(outputFolder, 'dir')
          mkdir(outputFolder);
          fprintf('Created folder : %s\n', outputFolder);
      end
      % Prepare output filename
      outputFileName = fullfile(outputFolder, baseFileName);
      % Write file to that folder
      imwrite(J, outputFileName);
      fprintf('    Copied %s to the folder called %s.\n', baseFileName, outputFolder);
    end
  end
  J
  HOG(J)
  X=HOG(J)
  save('features.mat','J');

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Answer 1

Ameer Hamza 2018-4-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397679-how-to-save-image-features-in-mat-file#answer_317472

在 MATLAB Online 中打开

In your code, the matrix you want to save is X, not J. Also, you are also calculating HOG feature for the last image. To calculate for all images and save them write your code as follows.

Before the start of first for loop add the following line

X = [];

At the end of inner for loop add the following line, like this

fprintf('    Copied %s to the folder called %s.\n', baseFileName, outputFolder); % line from your code
X{k, i} = HOG(J);

Each row in X represents HOG feature for one complete image. Each element in the row represents HOG features for one bounding box.

Then save the features like this

save('features.mat', 'X');

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saeeda saher 2018-4-29

编辑：saeeda saher 2018-4-29

在 MATLAB Online 中打开

I did it the way you guided:

myFolder = 'folder'; % or whatever.
if ~isdir(myFolder)
  errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
  uiwait(warndlg(errorMessage));
  return;
end
filePattern = fullfile(myFolder, '*.jpg');
matFiles = dir(filePattern);
   X=[]
for k = 1:length(matFiles)
  baseFileName = matFiles(k).name;
  img = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', img);
  storedStructure = imread(img);
  % Now do whatever you need to do with the structure you recalled.
  %figure    % New figure, do not specify the index
  %imshow(img);
  FaceDetect = vision.CascadeObjectDetector;
  FaceDetect.MergeThreshold = 7 ;
  BB = step(FaceDetect,storedStructure); %figure(2),imshow(img);
  for i = 1:size(BB,1)
     rectangle('Position',BB(i,:),'LineWidth',3,'LineStyle','- ','EdgeColor','r');
  end
  % figure
    for i = 1:size(BB,1)
      J= imcrop(storedStructure,BB(i,:));
      %subplot(6,6,i);
      figure
      imshow(J);
      % Create a folder with the base file name
      [~, baseFileNameNoExt, ~] = fileparts(baseFileName);
      outputFolder = fullfile(myFolder, baseFileNameNoExt);
      if ~exist(outputFolder, 'dir')
          mkdir(outputFolder);
          fprintf('Created folder : %s\n', outputFolder);
      end
      % Prepare output filename
      outputFileName = fullfile(outputFolder, baseFileName);
      % Write file to that folder
      imwrite(J, outputFileName);
      fprintf('    Copied %s to the folder called %s.\n', baseFileName, outputFolder);
       X{k, i} = HOG(J);
       save('features.mat', 'X');
    end
  end

It saves the features of image not in a complete row. I want the features in row not in column.

saeeda saher 2018-4-30

Thank You @Ameer Hamza

Ameer Hamza 2018-4-30

You are welcome.

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Answer 2

Walter Roberson 2018-4-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397679-how-to-save-image-features-in-mat-file#answer_317470

You are doing a loop with imcrop, but you are only storing the output for the current iteration in J. Afterwards, J is going to have the value it had on the last iteration of the loop. You are then applying HOG only to that one cropped version.

You should be calculating the HOG inside the loop and saving all of the results.