How to read and store greyscaleimage into single matrix?

Question

subha 2014-11-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/163677-how-to-read-and-store-greyscaleimage-into-single-matrix

评论： subha 2014-11-24

i have 2429 images in pgm format. each is in 19*19 size. Now i need to read all the images one by one and store in single matrix. With the help of previous mathworks available examples i read my file. now how to store in single matrix.

myFolder = 'C:\Users\smanohar\Documents\MATLAB\RBMimplementation\Gaussian    RBM\gdrbm\greyscsalegdrbm\face';
if ~isdir(myFolder)
errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
uiwait(warndlg(errorMessage));
return;
end
filePattern = fullfile(myFolder, '*.pgm');
jpegFiles = dir(filePattern);
for k = 1:length(jpegFiles)
baseFileName = jpegFiles(k).name;
fullFileName = fullfile(myFolder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
imageArray = imread(fullFileName);
end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Geoff Hayes 2014-11-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/163677-how-to-read-and-store-greyscaleimage-into-single-matrix#answer_159722

在 MATLAB Online 中打开

Subha - if all images are of the same dimension, 19x19, then you can save all of them to a single array of size 19x19x2429. Try something like the following

 % pre-size the image array
 imageArray = zeros(19,19,2429);
 filePattern = fullfile(myFolder, '*.pgm');
 pgmFiles = dir(filePattern);
 for k = 1:length(pgmFiles)
     baseFileName = pgmFiles(k).name;
     fullFileName = fullfile(myFolder, baseFileName);
     fprintf(1, 'Now reading %s\n', fullFileName);
     imageArray(:,:,k) = imread(fullFileName);
 end

Note how the kth image is stored in the imageArray. You may want to cast the imageArray to the appropriate data type before or after you have copied the images into it. (The appropriate data type being that of the pgm images.)

4 个评论
显示 2更早的评论隐藏 2更早的评论

Geoff Hayes 2014-11-22

在 MATLAB Online 中打开

Subha - why are you doing the following

imageArray= reshape(imageArray,19*19,k);

so that it is dependent upon k? Is this during each iteration or once finished and so outside the for loop?

If you want a matrix that is 2429x361, then why not do the following

 % pre-size the image array
 imageArray = zeros(2429,19*19);
 filePattern = fullfile(myFolder, '*.pgm');
 pgmFiles = dir(filePattern);
 for k = 1:length(pgmFiles)
     baseFileName = pgmFiles(k).name;
     fullFileName = fullfile(myFolder, baseFileName);
     fprintf(1, 'Now reading %s\n', fullFileName);
     imageArray(k,:) = reshape(imread(fullFileName),1,361);
 end