如何读取和存储图像文件夹 (MATLAB)

Question

我想从一个文件夹中读取一组图像，然后将其存储在一个数组中，这样如果我询问 imshow(imageArray(5)) 它会显示数组中的第 5 个图像。使用我从类似问题中找到的一些代码，到目前为止我有这个：

% Specify the folder where the files live.
myFolder = 'C:\Users\MyName\Documents\MATLAB\FolderName';

% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.tif'); % Change to whatever pattern you need.
theFiles = dir(filePattern);

imageArray = zeros(480, 1);

for k = 1 : length(theFiles)
  baseFileName = theFiles(k).name;
  fullFileName = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  % Now do whatever you want with this file name,
  % such as reading it in as an image array with imread()
  imageArray(k) = imread(fullFileName);
end

然而，当我这样做时，出现以下错误：

Unable to perform assignment because the left and right sides have a different number of elements.

Error in ImportTry (line 16) imageArray(k) = imread(fullFileName);

如何使用单个索引来索引高维数组？

Answer 1

错误是因为您用零初始化数组，因此图像的大小与数组元素的大小不对应。

你想要的是使用cells。

所以你要初始化你的单元格：

imageCell = cell(480, 1);

然后将图像分配给元胞数组的元素：

imageCell{k} = imread(fullFileName);

编辑：正如 Adriaan 在他的中指出的那样，如果您的图像大小在整个文件夹中保持一致，那么您最好使用 4D 矩阵。

Answer 2

您的代码的问题在于，在循环的最后一行中，您将尺寸为 1080x1920x3 uint8（对于全高清图像）的图像分配给大小为 480x1 的向量。这自然不行。因此，请尝试以下操作并使用元胞数组。

% Specify the folder where the files live.
myFolder = 'C:\Users\MyName\Documents\MATLAB\FolderName';

% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.tif'); % Change to whatever pattern you need.
theFiles = dir(filePattern);

imageArray = cell(size(theFiles)); % initialize cell array for speedup

for k = 1 : length(theFiles)
  baseFileName = theFiles(k).name;
  fullFileName = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  % Now do whatever you want with this file name,
  % such as reading it in as an image array with imread()
  imageArray(k) = {imread(fullFileName)};
end

% iterate cell array and display all images 1-by-1
for k = 1 : length(imageArray)
    imshow(cell2mat(imageArray(k)))
    pause; % press a button to continue
end

Answer 3

与此处的其他解决方案相反，我不会使用单元格，因为众所周知，单元格比矩阵慢。我只想要一个 4D 矩阵，其中前三个是 N 行、M 列、3 个 RGB 通道的图像，然后是图像的索引：

imageArray = zeros(N,M,3,480); % Where N and M are your image size
for k = 1 : length(theFiles)
  baseFileName = theFiles(k).name;
  fullFileName = fullfile(myFolder, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  % Now do whatever you want with this file name,
  % such as reading it in as an image array with imread()
  imageArray(:,:,:,k) = imread(fullFileName);
end

请注意，这仅适用于所有图像的形状完全相同的情况。如果没有，细胞或结构是可行的方法。

如何读取和存储图像文件夹 (MATLAB)

How to Read and Store a Folder of Images (MATLAB)

matlab

data-storage

image-processing