基于libjpeg-turbo库的jpeg4py安装与使用记录

前言

jpeg4py是Python cffi (C Foreign Function Interface) libjpeg-turbo 绑定和辅助类工具包，是为 libjpeg-turbo 提供线程安全和感知GIL的Python绑定，基于Python 2/3 和 numpy 运行。

目前只能解码 jpeg 文件，在单线程中比 Image.open().tobytes() 和 scipy.misc.imread() 快约 1.3 倍，在多线程模式下快 9 倍.

本文简要介绍基于libjpeg-turbo库的jpeg4py安装与使用。

安装

以Ubuntu为例进行说明：

root用户安装

sudo apt-get install libturbojpeg
pip install jpeg4py

普通用户安装

tar -xf libjpeg-turbo-2.1.2.tar.gz
cd libjpeg-turbo-2.1.2/
mkdir build
cd build
cmake -G"Unix Makefiles" -DCMAKE_INSTALL_PREFIX:PATH=/InstallPath/libjpeg-turbo-2.1.2/lib64 ..
make -j16
make install

如遇cmake报错如下：

cmake -G"Unix Makefiles" -DCMAKE_INSTALL_PREFIX:PATH=/InstallPath/libjpeg-turbo-2.1.2/lib64 ..
Command 'cmake' not found, but can be installed with:
snap install cmake # version 3.23.3, or
apt install cmake
See 'snap info cmake' for additional versions.

则安装cmake：

pip install cmake

将相关路径添加进环境变量：

vi ~/.bashrc

在末尾添加：
# libjpeg-turbo
export PATH=$PATH:/InstallPath/libjpeg-turbo-2.1.2/lib64/bin/
# (动态库搜索路径) 程序运行期间查找动态链接库时指定查找共享库的路径
export LD_LIBRARY_PATH=/InstallPath/libjpeg-turbo-2.1.2/lib64/lib/:$LD_LIBRARY_PATH
# (静态库搜索路径) 程序编译期间查找动态链接库时指定查找共享库的路径
export LIBRARY_PATH=/InstallPath/libjpeg-turbo-2.1.2/lib64/lib/:$LIBRARY_PATH
# c程序头文件搜索路径
export C_INCLUDE_PATH=/InstallPath/libjpeg-turbo-2.1.2/lib64/include/:$C_INCLUDE_PATH

source ~/.bashrc

pip install jpeg4py

使用

Python 3.7.10 | packaged by conda-forge | (default, Feb 19 2021, 16:07:37)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jpeg4py
>>> path = 'test.jpg'
>>> jpeg4py.JPEG(path).decode()

其他说明

如果libturbojpeg没有安装成功，则在调用jpeg4py方法时会报错：

Traceback (most recent call last):
File "", line 1, in
File "/data/conda/envs/test/lib/python3.7/site-packages/jpeg4py/_py.py"
, line 128, in __init__
super(JPEG, self).__init__(lib_)
File "/data/conda/envs/test/lib/python3.7/site-packages/jpeg4py/_py.py"
, line 64, in __init__
jpeg.initialize()
File "/data/conda/envs/test/lib/python3.7/site-packages/jpeg4py/_cffi.p
y", line 212, in initialize
_initialize(backends)
File "/data/conda/envs/test/lib/python3.7/site-packages/jpeg4py/_cffi.p
y", line 193, in _initialize
raise OSError("Could not load libjpeg-turbo library")

版权说明

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参考资料

[1] ajkxyz/jpeg4py: Python cffi libjpeg-turbo bindings and helper classes
[2] libjpeg-turbo/libjpeg-turbo: Main libjpeg-turbo repository
[3] 源码安装libjpeg-turbo1.2.1，无root权限_xiamentingtao的博客-优快云博客