我是靠谱客的博主 自觉跳跳糖,这篇文章主要介绍TensorFlow实现VGGNet网络模型1、VGGNet简介2、代码如下,现在分享给大家,希望可以做个参考。

1、VGGNet简介

VGGNet是牛津大学计算机视觉组和Google DeepMind公司的研究员一起研发的深度卷积神经网络,VGGNet探索了卷积神经网络的深度与其性能之间的关系,反复使用33的小型卷积核和22的最大池化层来构筑卷积神经网络。到目前为止,VGGNet依然经常被用来提取图像特征。
VGGNet拥有5段卷积,每一段内有2~3个卷积层,同时每段尾部会连接一个最大池层用来缩小图片尺寸。每段内的卷积核数量一样,越靠后的段的卷积核数量越多:64-128-256-512-512。

VGGNet特点:
(1)LRN层作用不大
(2)越深的网络效果越好
(3)11的卷积也是很有效的,但是没有33的卷积好,大一些的卷积核可以学习更大的空间特性。

2、代码如下

复制代码
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#导入库 import time import math import datetime import tensorflow as tf #函数conv_op,用来创建卷积层并把本层的参数存入参数列表 def conv_op(input_op, name, kh, kw, n_out, dh, dw, p): n_in = input_op.get_shape()[-1].value with tf.name_scope(name) as scope: kernel = tf.get_variable(scope+"w", shape=[kh, kw, n_in, n_out], dtype=tf.float32, initializer=tf.contrib.layers.xavier_initializer_conv2d()) conv = tf.nn.conv2d(input_op, kernel, (1, dh, dw, 1), padding='SAME') bias_init_val = tf.constant(0.0, shape=[n_out], dtype=tf.float32) biases = tf.Variable(bias_init_val, trainable=True, name='b') z = tf.nn.bias_add(conv, biases) activation = tf.nn.relu(z, name=scope) p +=[kernel, biases] return activation #定义全连接层的创建函数fc_op def fc_op(input_op, name, n_out, p): n_in = input_op.get_shape()[-1].value with tf.name_scope(name) as scope: kernel = tf.get_variable(scope+"w", shape=[n_in, n_out],dtype=tf.float32, initializer=tf.contrib.layers.xavier_initializer()) biases = tf.Variable(tf.constant(0.1, shape=[n_out], dtype=tf.float32), name='b') activation = tf.nn.relu_layer(input_op, kernel, biases, name=scope) p += [kernel, biases] return activation #定义最大池化层的创建函数mpool_op def mpool_op(input_op, name, kh, kw, dh, dw): return tf.nn.max_pool(input_op, ksize=[1, kh, kw, 1], strides=[1, dh, dw, 1], padding='SAME', name=name) #完成卷积层、池化层、最大连接层的创建 def inference_op(input_op, keep_prob): p = [] conv1_1 = conv_op(input_op, name="conv1_1", kh=3, kw=3, n_out=64, dh=1,dw=1, p=p) conv1_2 = conv_op(conv1_1, name="conv1_2", kh=3, kw=3, n_out=64, dh=1, dw=1, p=p) pool1 = mpool_op(conv1_2, name="pool1",kh=2,kw=2,dw=2,dh=2) conv2_1 = conv_op(pool1, name="conv2_1", kh=3, kw=3, n_out=128, dh=1, dw=1, p=p) conv2_2 = conv_op(conv2_1, name="conv2_2", kh=3, kw=3, n_out=128, dh=1, dw=1, p=p) pool2 = mpool_op(conv2_2, name="pool2", kh=2, kw=2, dw=2, dh=2) conv3_1 = conv_op(pool2, name="conv3_1", kh=3, kw=3, n_out=256, dh=1, dw=1, p=p) conv3_2 = conv_op(conv3_1, name="conv3_2", kh=3, kw=3, n_out=256, dh=1, dw=1, p=p) conv3_3 = conv_op(conv3_2, name="conv3_3", kh=3, kw=3, n_out=256, dh=1, dw=1, p=p) pool3 = mpool_op(conv3_3, name="pool3", kh=2, kw=2, dw=2, dh=2) conv4_1 = conv_op(pool3, name="conv4_1", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) conv4_2 = conv_op(conv4_1, name="conv4_2", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) conv4_3 = conv_op(conv4_2, name="conv4_3", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) pool4 = mpool_op(conv4_3, name="pool4", kh=2, kw=2, dw=2, dh=2) conv5_1 = conv_op(pool4, name="conv5_1", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) conv5_2 = conv_op(conv5_1, name="conv5_2", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) conv5_3 = conv_op(conv5_2, name="conv5_3", kh=3, kw=3, n_out=512, dh=1, dw=1, p=p) pool5 = mpool_op(conv5_3, name="pool5", kh=2, kw=2, dw=2, dh=2) shp = pool5.get_shape() flattened_shape = shp[1].value * shp[2].value * shp[3].value resh1 = tf.reshape(pool5, [-1, flattened_shape], name="resh1") fc6 = fc_op(resh1,name="fc6", n_out=4096, p=p) fc6_drop = tf.nn.dropout(fc6, keep_prob, name="fc6_drop") fc7 = fc_op(fc6_drop,name="fc7",n_out=4096,p=p) fc7_drop = tf.nn.dropout(fc7, keep_prob, name="fc7_drop") fc8 = fc_op(fc7_drop, name="fc8", n_out=1000, p=p) softmax = tf.nn.softmax(fc8) predictions = tf.argmax(softmax, 1) return predictions, softmax, fc8, p #评测函数 def time_tensorflow_run(session,target, feed, info_string): num_steps_burn_in = 10 total_duration = 0.0 total_duration_squared = 0.0 for i in range(num_batches + num_steps_burn_in): start_time = time.time() _ = session.run(target, feed_dict=feed) duration = time.time() - start_time if i >= num_steps_burn_in: if not i % 10: print('%s: step %d, duration = %.3f' % (datetime.datetime.now(), i-num_steps_burn_in,duration)) total_duration += duration total_duration_squared += duration * duration mn = total_duration / num_batches vr = total_duration_squared / num_batches - mn * mn sd = math.sqrt(vr) print('%s: %s across %d steps, %.3f +/- %.3f sec / batch' % (datetime.datetime.now(), info_string, num_batches, mn,sd)) #定义主函数 def run_benchmark(): with tf.Graph().as_default(): image_size = 224 images = tf.Variable(tf.random_normal([batch_size,image_size, image_size, 3], dtype=tf.float32, stddev=1e-1)) keep_prob = tf.placeholder(tf.float32) predictions, softmax, fc8, p = inference_op(images, keep_prob) init = tf.global_variables_initializer() sess = tf.Session() sess.run(init) time_tensorflow_run(sess, predictions, {keep_prob:1.0}, "Forward") objective = tf.nn.l2_loss(fc8) grad = tf.gradients(objective, p) time_tensorflow_run(sess, grad, {keep_prob:0.5}, "Forward-backward") batch_size=32 num_batches=100 run_benchmark()

最后

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