function mnist2matlab(mnist_dir)

% function MNIST2MATLAB(MNIST_DIR)

% Converts and saves MNIST datasets from lush IDX data as Matlab files.

%

% INPUT

% MNIST_DIR - directory to MNIST dataset

%

% Matlab code by Nikolay Chumerin, K.U.Leuven, Belgium.

% Nikolay.Chumerin@med.kuleuven.be

% http://simone.neuro.kuleuven.be/nick

% Last update: 2009-09-08

% read test data file

images = permute(read_idx_data([mnist_dir 't10k-images-idx3-ubyte']), [2 3 1]); %#ok<*NASGU>

save([mnist_dir 'test_images.mat'], 'images')

labels = read_idx_data([mnist_dir 't10k-labels-idx1-ubyte'])'; %#ok<*NASGU>

save([mnist_dir 'test_labels.mat'], 'labels')

% read train data file

images = permute(read_idx_data([mnist_dir 'train-images-idx3-ubyte']), [2 3 1]);

save([mnist_dir 'train_images.mat'], 'images')

labels = read_idx_data([mnist_dir 'train-labels-idx1-ubyte'])';

save([mnist_dir 'train_labels.mat'], 'labels')

end % of function MNIST2MATLAB

function data = read_idx_data(filename)

% function DATA = READ_IDX_DATA(FILENAME)

% Read data from lush IDX data file.

%

% INPUT

% FILENAME - name of the lush IDX file

%

% OUTPUT

% DATA - result data

%

% Matlab code by Nikolay Chumerin, K.U.Leuven, Belgium.

% Nikolay.Chumerin@med.kuleuven.be

% http://simone.neuro.kuleuven.be/nick

% Last update: 2009-01-12

% check parameters

if ~exist('filename', 'var') || isempty(filename),

error('Should be at least one parameter - filename!');

end

% try to open file

try

f = fopen(filename);

catch %#ok<*CTCH>

error(['Can''data open file ' filename]);

end

% check file's signature / magic number

magic = int32(fread(f, 4, 'uint8'));

switch magic(3),

case 08, format = 'uint8'; % 0x08: unsigned byte

case 09, format = 'int8'; % 0x09: signed byte

case 13, format = 'single'; % 0x0D: float (4 bytes)

case 14, format = 'double'; % 0x0E: double (8 bytes)

otherwise

error('Unsupported data format');

end % of format switch

% Read dimensions

ndim = double(magic(4)); % number of dimensions

dims = fread(f, ndim, 'uint32', 'ieee-be')'; % dimensions

if ndim == 1,

dims = [dims 1];

ndim = 2;

end

data = reshape(fread(f, prod(dims), ['*' format]), fliplr(dims)); % reshape

data = permute(data, ndim:-1:1); % permute dimensions

fclose(f); % close the file

end % of function READ_IDX_DATA