技术背景

对于各行各业的研究人员来说，经常会面临这样的一个问题：有一篇不错的文章里面有很好的数据，但是这个数据在文章中仅以图片的形式出现。而假如我们希望可以从该图片中提取出数据，这样就可以用我们自己的形式重新来展现这些数据，还可以额外再附上自己优化后的数据。因此从论文图片中提取数据，是一个非常实际的需求。这里以前面写的量子退火的博客为例，博客中有这样的一张图片：

在这篇文章中，我们将介绍如何使用python从图片上把数据抠取出来。

plotdigitizer的安装

这里我们使用pip来安装python第三方库plotdigitizer，该库的主要功能就是可以自动化的从图片中提取出数据，我们可以使用腾讯的pip镜像源来加速我们的安装过程：

```

[dechin@dechin-manjaro plotdigitizer]$ python3 -m pip install -i https://mirrors.cloud.tencent.com/pypi/simple plotdigitizer

Looking in indexes: https://mirrors.cloud.tencent.com/pypi/simple

Collecting plotdigitizer

Downloading https://mirrors.cloud.tencent.com/pypi/packages/89/bb/ff753093458c05ce3b52fd17527b6b0622ca096aadcf561c6316320ab793/plotdigitizer-0.1.3-py3-none-any.whl (20 kB)

Collecting loguru<0.6.0,>=0.5.3

Downloading https://mirrors.cloud.tencent.com/pypi/packages/6d/48/0a7d5847e3de329f1d0134baf707b689700b53bd3066a5a8cfd94b3c9fc8/loguru-0.5.3-py3-none-any.whl (57 kB)

|████████████████████████████████| 57 kB 521 kB/s

Collecting opencv-python<5.0.0,>=4.5.1

Downloading https://mirrors.cloud.tencent.com/pypi/packages/2a/9a/ff309b530ac1b029bfdb9af3a95eaff0f5f45f6a2dbe37b3454ae8412f4c/opencv_python-4.5.1.48-cp38-cp38-manylinux2014_x86_64.whl (50.4 MB)

|████████████████████████████████| 50.4 MB 467 kB/s

Collecting numpy<2.0.0,>=1.19.5

Downloading https://mirrors.cloud.tencent.com/pypi/packages/c7/e6/dccac76b7e825915ffb906beeba5a953597b6cfe1fe686b5276e122cb07c/numpy-1.20.1-cp38-cp38-manylinux2010_x86_64.whl (15.4 MB)

|████████████████████████████████| 15.4 MB 20.4 MB/s

Collecting matplotlib<4.0.0,>=3.3.4

Downloading https://mirrors.cloud.tencent.com/pypi/packages/ab/20/60cfe5d611ac86df07b7b1f9b9582f22f7eda5edbe2124ba85bdf3133822/matplotlib-3.3.4-cp38-cp38-manylinux1_x86_64.whl (11.6 MB)

|████████████████████████████████| 11.6 MB 4.4 MB/s

Requirement already satisfied: python-dateutil>=2.1 in /home/dechin/anaconda3/lib/python3.8/site-packages (from matplotlib<4.0.0,>=3.3.4->plotdigitizer) (2.8.1)

Requirement already satisfied: cycler>=0.10 in /home/dechin/anaconda3/lib/python3.8/site-packages (from matplotlib<4.0.0,>=3.3.4->plotdigitizer) (0.10.0)

Requirement already satisfied: pillow>=6.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from matplotlib<4.0.0,>=3.3.4->plotdigitizer) (8.0.1)

Requirement already satisfied: kiwisolver>=1.0.1 in /home/dechin/anaconda3/lib/python3.8/site-packages (from matplotlib<4.0.0,>=3.3.4->plotdigitizer) (1.3.0)

Requirement already satisfied: pyparsing!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.3 in /home/dechin/anaconda3/lib/python3.8/site-packages (from matplotlib<4.0.0,>=3.3.4->plotdigitizer) (2.4.7)

Requirement already satisfied: six>=1.5 in /home/dechin/anaconda3/lib/python3.8/site-packages (from python-dateutil>=2.1->matplotlib<4.0.0,>=3.3.4->plotdigitizer)