Caffe代码导读（4）：数据集准备

Caffe上面有两个比较简单的例子：MNIST和CIFAR-10，前者是用于手写数字识别的，后者用于小图片分类。这两个数据集可以在Caffe源码框架中用脚本（CAFFE_ROOT/data/mnist/get_mnist.sh和CAFFE_ROOT/data/cifar10/get_cifar10.sh）下载，如下图所示：

$ ./get_cifar10.sh
Downloading...
--2014-12-02 01:20:12--  http://www.cs.toronto.edu/~kriz/cifar-10-binary.tar.gz
Resolving www.cs.toronto.edu... 128.100.3.30
Connecting to www.cs.toronto.edu|128.100.3.30|:80... connected.
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Saving to: “cifar-10-binary.tar.gz”

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2014-12-02 01:22:28 (1.20 MB/s) - “cifar-10-binary.tar.gz” saved [170052171/170052171]

Unzipping...
Done.
$ ls
batches.meta.txt  data_batch_1.bin  data_batch_2.bin  data_batch_3.bin  data_batch_4.bin  data_batch_5.bin  get_cifar10.sh  readme.html  test_batch.bin

$ ./get_mnist.sh
Downloading...
--2014-12-02 01:24:25--  http://yann.lecun.com/exdb/mnist/train-images-idx3-ubyte.gz
Resolving yann.lecun.com... 128.122.47.89
Connecting to yann.lecun.com|128.122.47.89|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 9912422 (9.5M) [application/x-gzip]
Saving to: “train-images-idx3-ubyte.gz”

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2014-12-02 01:24:33 (1.42 MB/s) - “train-images-idx3-ubyte.gz” saved [9912422/9912422]

--2014-12-02 01:24:33--  http://yann.lecun.com/exdb/mnist/train-labels-idx1-ubyte.gz
Resolving yann.lecun.com... 128.122.47.89
Connecting to yann.lecun.com|128.122.47.89|:80... connected.
HTTP request sent, awaiting response... 200 OK
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Saving to: “train-labels-idx1-ubyte.gz”

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2014-12-02 01:24:34 (42.0 KB/s) - “train-labels-idx1-ubyte.gz” saved [28881/28881]

--2014-12-02 01:24:34--  http://yann.lecun.com/exdb/mnist/t10k-images-idx3-ubyte.gz
Resolving yann.lecun.com... 128.122.47.89
Connecting to yann.lecun.com|128.122.47.89|:80... connected.
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Saving to: “t10k-images-idx3-ubyte.gz”

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2014-12-02 01:24:39 (552 KB/s) - “t10k-images-idx3-ubyte.gz” saved [1648877/1648877]

--2014-12-02 01:24:39--  http://yann.lecun.com/exdb/mnist/t10k-labels-idx1-ubyte.gz
Resolving yann.lecun.com... 128.122.47.89
Connecting to yann.lecun.com|128.122.47.89|:80... connected.
HTTP request sent, awaiting response... 200 OK
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Saving to: “t10k-labels-idx1-ubyte.gz”

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2014-12-02 01:24:40 (19.8 KB/s) - “t10k-labels-idx1-ubyte.gz” saved [4542/4542]

Unzipping...
Done.
$ ls
get_mnist.sh  t10k-images-idx3-ubyte  t10k-labels-idx1-ubyte  train-images-idx3-ubyte  train-labels-idx1-ubyte

如果你下载出现问题可以从我的资源处获取，网址http://download.csdn.net/detail/kkk584520/8213463。

原始数据集为二进制文件，需要转换为leveldb或lmdb才能被Caffe识别。转换格式的工具已经集成在Caffe代码中，见CAFFE_ROOT/examples/mnist/convert_mnist_data.cpp

和CAFFE_ROOT/examples/cifar10/convert_cifar_data.cpp，如果对leveldb或lmdb操作不熟悉可以从这两个源代码中学习。我们只需要在CAFFE_ROOT目录中执行两条命令即可：

./examples/mnist/create_mnist.sh

./examples/cifar10/create_cifar10.sh