python操作PDF文件（转文本、图片）

最近在批量处理pdf文件。由于pdf中的格式比较多，所以在处理上有一定的难度。
我这里的思路是：如果能分析出文本就提取文本，如果不能分析出文本就转为jpg。（因为后面我还要处理jpg文件，所以也不在乎多一些）
因为之前提到过处理pdf文本的，所以这里就不在赘述。就说说把pdf中每页的内容抓为jpg格式吧。
这里因为要处理图片，所以用到了wand这个库

安装：pip3 install wand

然后就可以编写脚本来转换

from wand.image import Image
# 将pdf文件转为jpg图片文件
# ./PDF_FILE_NAME 为pdf文件路径和名称
def pdf2jpg(filename):
    image_pdf = Image(filename=filename,resolution=300)
    image_jpeg = image_pdf.convert('jpg')
    # wand已经将PDF中所有的独立页面都转成了独立的二进制图像对象。我们可以遍历这个大对象，并把它们加入到req_image序列中去。
    req_image = []
    for img in image_jpeg.sequence:
        img_page = Image(image=img)
        req_image.append(img_page.make_blob('jpg'))
    # 遍历req_image,保存为图片文件
    i = 0
    for img in req_image:
        ff = open(str(i)+'.jpg','wb')
        ff.write(img)
        ff.close()
        i += 1

filename='/home/filename.pdf'
pdf2jpg(filename)

然后运行，嘿嘿，报错：Imagick - ImagickException not… @ error / construct.c / ReadImage / 412错误
然后再百度了一下，我这边是ubuntu，cd到/etc/ImageMagick-6
然后用vi 打开policy.xml
编辑内容如下（其实与它里面原本的内容并无多大区别，主要是最后中的内容）
然后保存退出，再次运行，啦啦啦啦，prefect!!!

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE policymap [
<!ELEMENT policymap (policy)+>
<!ELEMENT policy (#PCDATA)>
<!ATTLIST policy domain (delegate|coder|filter|path|resource) #IMPLIED>
<!ATTLIST policy name CDATA #IMPLIED>
<!ATTLIST policy rights CDATA #IMPLIED>
<!ATTLIST policy pattern CDATA #IMPLIED>
<!ATTLIST policy value CDATA #IMPLIED>
]>
<!--
  Configure ImageMagick policies.

  Domains include system, delegate, coder, filter, path, or resource.

  Rights include none, read, write, and execute.  Use | to combine them,
  for example: "read | write" to permit read from, or write to, a path.

  Use a glob expression as a pattern.

  Suppose we do not want users to process MPEG video images:

    <policy domain="delegate" rights="none" pattern="mpeg:decode" />

  Here we do not want users reading images from HTTP:

    <policy domain="coder" rights="none" pattern="HTTP" />

  Lets prevent users from executing any image filters:

    <policy domain="filter" rights="none" pattern="*" />

  The /repository file system is restricted to read only.  We use a glob
  expression to match all paths that start with /repository:

    <policy domain="path" rights="read" pattern="/repository/*" />

  Any large image is cached to disk rather than memory:

    <policy domain="resource" name="area" value="1GB"/>

  Define arguments for the memory, map, area, and disk resources with
  SI prefixes (.e.g 100MB).  In addition, resource policies are maximums for
  each instance of ImageMagick (e.g. policy memory limit 1GB, -limit 2GB
  exceeds policy maximum so memory limit is 1GB).
-->
<policymap>
  <!-- <policy domain="resource" name="temporary-path" value="/tmp"/> -->
  <!-- <policy domain="resource" name="memory" value="2GiB"/> -->
  <!-- <policy domain="resource" name="map" value="4GiB"/> -->
  <!-- <policy domain="resource" name="area" value="1GB"/> -->
  <!-- <policy domain="resource" name="disk" value="16EB"/> -->
  <!-- <policy domain="resource" name="file" value="768"/> -->
  <!-- <policy domain="resource" name="thread" value="4"/> -->
  <!-- <policy domain="resource" name="throttle" value="0"/> -->
  <!-- <policy domain="resource" name="time" value="3600"/> -->
  <!-- <policy domain="system" name="precision" value="6"/> -->
  <policy domain="cache" name="shared-secret" value="passphrase"/>
  <policy domain="coder" rights="none" pattern="EPHEMERAL" />
  <policy domain="coder" rights="none" pattern="URL" />
  <policy domain="coder" rights="none" pattern="HTTPS" />
  <policy domain="coder" rights="none" pattern="MVG" />
  <policy domain="coder" rights="none" pattern="MSL" />
  <policy domain="coder" rights="none" pattern="TEXT" />
  <policy domain="coder" rights="none" pattern="SHOW" />
  <policy domain="coder" rights="none" pattern="WIN" />
  <policy domain="coder" rights="none" pattern="PLT" />
  <policy domain="path" rights="none" pattern="@*" />
</policymap>