TensorFlow——训练自己的数据——CIFAR10（一）数据准备

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/xinyu3307/article/details/77072789

参考教程:Tensorflow教程：深度学习 图像分类 CIFAR10数据集

---

Reading Data
所用函数

def read_cifar10(data_dir, is_train, batch_size, shuffle):`
    Args:
        data_dir: the directory of CIFAR10
        is_train: boolen
        batch_size:
        shuffle:   #是否打乱顺序   
    Returns:
        label: 1D tensor, tf.int32
        image: 4D tensor, [batch_size, height, width, 3], tf.float32

变量声明

img_width = 32
img_height = 32
img_depth = 3
label_bytes = 1
image_bytes = img_width*img_height*img_depth #32x32x3=3072

读取数据

#将以下操作放在一个作用域内，使得tensorboard更美观
    with tf.name_scope('input'):

        #如果是训练数据，则将文件的路径赋值给filenames，注意到data的命名规律为data_batch_n.bin
        #os.path.join(“home”, "me", "mywork"),在linux返回“home/me/mywork"，在windows上返回"home\me\mywork"
        #好处是可以根据系统自动选择正确的路径分隔符"/"或"\"
        if is_train:
            filenames = [os.path.join(data_dir, '/data_batch_%d.bin' %ii)
                                        for ii in np.arange(1, 5)]
        else:
            filenames = [os.path.join(data_dir, '/test_batch.bin')]

        #产生一个队列，因为使用的是二进制，所以使用string_input_producer
        #ps:之前猫狗大战是label+img,用的是slice_input_producer
        filename_queue = tf.train.string_input_producer(filenames)
        #读取数据，label_bytes=1，image_bytes=32*32*3=3072
        reader = tf.FixedLengthRecordReader(label_bytes + image_bytes)

        key, value = reader.read(filename_queue)
        #对读取到的数据解码decode   
        #ps：猫狗大战的数据是img，用的解码器是tf.image.decode_jpeg
        record_bytes = tf.decode_raw(value, tf.uint8)
        #data包含了label和image，所以通过slice切片，把他们分开，这里切了个[0,1]
        label = tf.slice(record_bytes, [0], [label_bytes])   
        label = tf.cast(label, tf.int32)
        #切[1,3072]
        image_raw = tf.slice(record_bytes, [label_bytes], [image_bytes])
        #将二进制数据reshape为图像数据[0-depth,1-height,2-width]=[3,32,32]
        image_raw = tf.reshape(image_raw, [img_depth, img_height, img_width])
        #转换为[1-height,2-width,0-depth]
        image = tf.transpose(image_raw, (1,2,0)) # convert from D/H/W to H/W/D       
        image = tf.cast(image, tf.float32)


#        # data argumentation,图像增强（裁剪、旋转、缩放等），但据说效果不怎么样

#        image = tf.random_crop(image, [24, 24, 3])# randomly crop the image size to 24 x 24
#        image = tf.image.random_flip_left_right(image)
#        image = tf.image.random_brightness(image, max_delta=63)
#        image = tf.image.random_contrast(image,lower=0.2,upper=1.8)


        #归一化操作从[0,255]到[-1,1]
        image = tf.image.per_image_standardization(image) #substract off the mean and divide by the variance 

        #是否打乱顺序
        if shuffle:
            images, label_batch = tf.train.shuffle_batch(
                                    [image, label], 
                                    batch_size = batch_size,
                                    num_threads= 16,
                                    capacity = 2000, #队列的容量
                                    min_after_dequeue = 1500)#队列取出后的最小值
        else:
            images, label_batch = tf.train.batch(
                                    [image, label],
                                    batch_size = batch_size,
                                    num_threads = 16,
                                    capacity= 2000)

#        return images, tf.reshape(label_batch, [batch_size])

## ONE-HOT ，将label转换成[1,0,0,0,0,0,0,0,0,0]的形式（第一个类为正确）     
        n_classes = 10
        label_batch = tf.one_hot(label_batch, depth= n_classes)
        return images, tf.reshape(label_batch, [batch_size, n_classes])

---

测试数据
把一个Batch显示出来

import matplotlib.pyplot as plt
#这里用自己的data路径
data_dir = 'D:/Study/Python/Projects/CIFAR10/data'
BATCH_SIZE = 2  #一个batch两张图
image_batch, label_batch = read_cifar10(data_dir,
                                        is_train=True,
                                        batch_size=BATCH_SIZE, 
                                        shuffle=True)

with tf.Session() as sess:
    i = 0
    #用coord和threads监控队列
    coord = tf.train.Coordinator()
    threads = tf.train.start_queue_runners(coord=coord)

    try:
        while not coord.should_stop() and i<1:

            img, label = sess.run([image_batch, label_batch])

            # just test one batch
            for j in np.arange(BATCH_SIZE):
                print('label: %d' %label[j])
                plt.imshow(img[j,:,:,:])
                plt.show()
            i+=1

    except tf.errors.OutOfRangeError:
        print('done!')
    finally:
        coord.request_stop()
    coord.join(threads)

结果
归一化和float类型导致图片显示失真