cnn相關操作
x = tf.placeholder('float32', [1, None, None, 1])
conv = tf.nn.conv2d(x, filter_weight, strides = [1, 2, 2, 1], padding = 'SAME')
bias = tf.nn.bias_add(conv, biases)
pool = tf.nn.avg_pool(x, ksize=[1, 2, 2, 1], strides=[1, 2, 2, 1], padding='SAME')