问题
The Imagemagick security policy seems to be not allowing me perform this conversion from pdf to png. Converting other extensions seem to be working, just not from pdf. I haven't changed any of the imagemagick settings since I installed it... I am using Arch Linux, if the OS matters.
user@machine $ convert -density 300 -depth 8 -quality 90 input.pdf output.png
convert: attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/408.
convert: no images defined `output.png' @ error/convert.c/ConvertImageCommand/3288.
回答1:
Well, I added
<policy domain="coder" rights="read | write" pattern="PDF" />
just before </policymap> in /etc/ImageMagick-7/policy.xml and that makes it work again, but not sure about the security implications of that.
回答2:
As pointed out in some comments, you need to edit the policies of ImageMagick in /etc/ImageMagick-7/policy.xml. More particularly, in ArchLinux at the time of writing (05/01/2019) the following line is uncommented:
<policy domain="coder" rights="none" pattern="{PS,PS2,PS3,EPS,PDF,XPS}" />
Just wrap it between <!-- and --> to comment it, and pdf conversion should work again.
回答3:
For me on my archlinux system the line was already uncommented. I had to replace "none" by "read | write " to make it work.
回答4:
for me on arch linux i had to comment:
<policy domain="delegate" rights="none" pattern="gs" />
回答5:
On Ubuntu 19.10, I have done this in /etc/ImageMagick-6/policy.xml
uncomment this
<policy domain="module" rights="read | write" pattern="{PS,PDF,XPS}" />
and comment this
<!-- <policy domain="coder" rights="none" pattern="PDF" /> -->
After that, this command work without error
convert -thumbnail x300 -background white -alpha remove sample.pdf sample.png
来源：https://stackoverflow.com/questions/52998331/imagemagick-security-policy-pdf-blocking-conversion