程序中需导入如下模块：
from skimage.metrics import peak_signal_noise_ratio as compare_psnr
报错：
ModuleNotFoundError: No module named 'skimage.metrics'
尝试重新安装skimage：
(pytorch) D:\MINE>pip install scikit-image
Requirement already satisfied: scikit-image in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (0.14.2)
Requirement already satisfied: matplotlib>=2.0.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (2.2.2)
Requirement already satisfied: networkx>=1.8 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (2.3)
Requirement already satisfied: six>=1.10.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (1.16.0)
Requirement already satisfied: pillow>=4.3.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (8.3.1)
Requirement already satisfied: PyWavelets>=0.4.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (1.1.1)
Requirement already satisfied: dask[array]>=1.0.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (2021.8.1)
Requirement already satisfied: cloudpickle>=0.2.1 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from scikit-image) (1.6.0)
Requirement already satisfied: packaging>=20.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (21.0)
Requirement already satisfied: fsspec>=0.6.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (2021.8.1)
Requirement already satisfied: partd>=0.3.10 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (1.2.0)
Requirement already satisfied: toolz>=0.8.2 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (0.11.1)
Requirement already satisfied: pyyaml in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (5.4.1)
Requirement already satisfied: numpy>=1.18 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from dask[array]>=1.0.0->scikit-image) (1.21.2)
Requirement already satisfied: cycler>=0.10 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from matplotlib>=2.0.0->scikit-image) (0.10.0)
Requirement already satisfied: pyparsing!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.1 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from matplotlib>=2.0.0->scikit-image) (2.4.7)
Requirement already satisfied: python-dateutil>=2.1 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from matplotlib>=2.0.0->scikit-image) (2.8.2)
Requirement already satisfied: pytz in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from matplotlib>=2.0.0->scikit-image) (2021.1)
Requirement already satisfied: kiwisolver>=1.0.1 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from matplotlib>=2.0.0->scikit-image) (1.3.2)
Requirement already satisfied: decorator>=4.3.0 in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from networkx>=1.8->scikit-image) (4.4.2)
Requirement already satisfied: locket in d:\myapps\anaconda\install\envs\pytorch\lib\site-packages (from partd>=0.3.10->dask[array]>=1.0.0->scikit-image) (0.2.0)
可以看到 skimage 已经安装过了，版本为0.14.2。
从ImportError: cannot import name ‘metrics’ from 'skimage’这篇文章得知是因为我安装的skimage版本过低，导致没有metrics：
Try to install latest version of skimage because that version does not have that module in it so use below command to upgrade it!
因此输入：
pip install scikit-image --upgrade
更新skimage版本即可，更新后的版本为0.18.3，模块可以正常导入。