php - How to add extra meta data to PNG?

Question

is there a way to add some extra metadata to a PNG file and then retrieve it with PHP ?

like Comment field.

Answer 1

If you have ImageMagick installed, it comes with two utilities: mogrify and identify.

To add comments:

$ mogrify.exe -comment "My test comment" plogo.png

To retrieve comments:

$ identify.exe -verbose plogo.png  | grep -i "comment:"
    comment: My test comment

I don't know if mogrify/identify functions are available as PHP libraries, but you can always use the php system command.