python实现图片风格转换
时间: 2023-07-25 09:10:42 浏览: 61
实现图片风格转换可以使用深度学习模型,比较常用的是基于卷积神经网络的风格迁移(Style Transfer)模型。下面是一个简单的代码示例:
首先需要安装必要的库,包括tensorflow, numpy, scipy, matplotlib等。
```python
import tensorflow as tf
import numpy as np
import scipy.misc
import matplotlib.pyplot as plt
```
定义读取图片的函数,使用scipy库的imread函数。
```python
def load_image(path):
img = scipy.misc.imread(path).astype(np.float)
# 将图片缩放至合适的大小
img = scipy.misc.imresize(img, (256, 256))
# 减去均值,使图片的像素值在[-127.5, 127.5]之间
img = img - np.mean(img)
return img
```
定义保存图片的函数。
```python
def save_image(image, path):
# 加上均值,还原像素值
image = image + np.mean(image)
# 裁剪像素值,使其在[0, 255]之间
image = np.clip(image, 0, 255).astype(np.uint8)
# 保存图片
scipy.misc.imsave(path, image)
```
加载内容图片和风格图片。
```python
content_image = load_image("content.jpg")
style_image = load_image("style.jpg")
```
定义模型中间层的名称和权重。
```python
# VGG19模型中间层的名称和权重
content_layers = ["block5_conv2"]
style_layers = ["block1_conv1", "block2_conv1", "block3_conv1", "block4_conv1", "block5_conv1"]
content_weight = 1
style_weight = 0.2
```
加载VGG19模型,并提取指定的中间层的特征。
```python
def get_features(image, model):
# 将图片输入模型,得到各个中间层的输出
outputs = [layer.output for layer in model.layers]
# 构建新的模型,以中间层的输出作为输出
feature_model = tf.keras.models.Model(model.input, outputs)
# 将图片预处理,使其符合模型的输入要求
image = np.expand_dims(image, axis=0)
image = tf.keras.applications.vgg19.preprocess_input(image)
# 将图片输入模型,得到各个中间层的输出
features = feature_model(image)
# 将不同层的特征拼接起来
features = [np.reshape(feature[0], (-1, feature.shape[3])) for feature in features]
features = np.concatenate(features, axis=0)
return features
```
定义Gram矩阵的计算函数。
```python
def gram_matrix(features):
# 计算Gram矩阵
gram = np.matmul(features.T, features)
return gram
```
定义内容损失的计算函数。
```python
def content_loss(content_features, generated_features):
# 计算内容损失
loss = tf.reduce_mean(tf.square(content_features - generated_features))
return content_weight * loss
```
定义风格损失的计算函数。
```python
def style_loss(style_features, generated_features):
# 计算Gram矩阵
style_gram = gram_matrix(style_features)
generated_gram = gram_matrix(generated_features)
# 计算风格损失
loss = tf.reduce_mean(tf.square(style_gram - generated_gram))
return style_weight * loss
```
定义总损失的计算函数。
```python
def total_loss(model, content_image, style_image, generated_image):
# 提取内容图片、风格图片和生成图片的特征
content_features = get_features(content_image, model)
style_features = get_features(style_image, model)
generated_features = get_features(generated_image, model)
# 计算内容损失和风格损失
content_loss_value = content_loss(content_features, generated_features)
style_loss_value = style_loss(style_features, generated_features)
# 计算总损失
total_loss_value = content_loss_value + style_loss_value
return total_loss_value
```
定义梯度下降函数,使用Adam优化器。
```python
def train_step(model, content_image, style_image, generated_image):
with tf.GradientTape() as tape:
# 计算总损失
loss = total_loss(model, content_image, style_image, generated_image)
# 计算梯度
gradients = tape.gradient(loss, generated_image)
# 使用Adam优化器更新生成图片
optimizer = tf.keras.optimizers.Adam(learning_rate=0.02, beta_1=0.99, epsilon=1e-1)
optimizer.apply_gradients([(gradients, generated_image)])
# 将像素值裁剪到[0, 255]之间
generated_image.assign(tf.clip_by_value(generated_image, 0, 255))
```
开始训练,迭代1000次。
```python
# 加载VGG19模型
model = tf.keras.applications.vgg19.VGG19(include_top=False, weights="imagenet")
# 将内容图片作为初始值
generated_image = tf.Variable(content_image)
# 训练1000次
for i in range(1000):
train_step(model, content_image, style_image, generated_image)
if i % 100 == 0:
# 每100次保存一次生成图片
save_image(generated_image.numpy(), "generated_%d.jpg" % i)
```
代码中的超参数可以根据具体的需求进行调整。实现图片风格转换需要一定的计算资源,建议在GPU环境下运行。