使用Matlab将MNIST数据集转化为.jpg .png .bmp图像格式

使用Matlab将MNIST数据集转化为.jpg .png .bmp图像格式

clear;

tic;

img_train = loadMNISTImages(‘train-images.idx3-ubyte’);

label_train = loadMNISTLabels(‘train-labels.idx1-ubyte’);

img_test = loadMNISTImages(‘t10k-images.idx3-ubyte’);

label_test = loadMNISTLabels(‘t10k-labels.idx1-ubyte’);

mkdir(‘train’);

mkdir(‘test’);

for i=0:9

mkdir(strcat(‘train’,num2str(i)));

end

for i=0:9

mkdir(strcat(‘test’,num2str(i)));

end

for i=1:60000

img=reshape(img_train(:,i),28,28);

%可以转换为任意图像格式.jpg .png .bmp

imwrite(img,strcat(‘train’,num2str(label_train(i)),’’,num2str(label_train(i)),’’,num2str(i),’.jpg’));

end

for i=1:10000

img=reshape(img_test(:,i),28,28);

imwrite(img,strcat(‘test’,num2str(label_test(i)),’’,num2str(label_test(i)),’’,num2str(i),’.jpg’));

end

toc;

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loadMNISTImages.m、loadMNISTLabels.m来源于网络

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function images = loadMNISTImages(filename)

%loadMNISTImages returns a 28x28x[number of MNIST images] matrix containing

%the raw MNIST images

fp = fopen(filename, ‘rb’);

assert(fp ~= -1, ['Could not open ', filename, ‘’]);

magic = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

assert(magic == 2051, ['Bad magic number in ', filename, ‘’]);

numImages = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

numRows = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

numCols = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

images = fread(fp, inf, ‘unsigned char’);

images = reshape(images, numCols, numRows, numImages);

images = permute(images,[2 1 3]);

fclose(fp);

% Reshape to #pixels x #examples

images = reshape(images, size(images, 1) * size(images, 2), size(images, 3));

% Convert to double and rescale to [0,1]

images = double(images) / 255;

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function labels = loadMNISTLabels(filename)

%loadMNISTLabels returns a [number of MNIST images]x1 matrix containing

%the labels for the MNIST images

fp = fopen(filename, ‘rb’);

assert(fp ~= -1, ['Could not open ', filename, ‘’]);

magic = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

assert(magic == 2049, ['Bad magic number in ', filename, ‘’]);

numLabels = fread(fp, 1, ‘int32’, 0, ‘ieee-be’);

labels = fread(fp, inf, ‘unsigned char’);

assert(size(labels,1) == numLabels, ‘Mismatch in label count’);

fclose(fp);

end

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