Wednesday, January 20, 2016

How to add watermark to a bunch of pictures

Adding a watermark to many pictures using a powerful tool as GIMP may take a long time. Let's see how we can get this done easily in command line.

You need:
  • The software graphicsmagick installed (sudo aptitude install graphicsmagick)
  • Your watermark with transparent background (mine is a PNG image)
  • A directory with your original pictures
  • A directory for your signed pictures
For this example, consider that:

  • My pictures are in ~/Pictures/Lake, my signed pictures will be at ~/Pictures/Lake/Signed and my watermark is ~/Pictures/sign.png.
  • All my original pictures have an extension .jpg.
  • Also, my watermark will be written in lower right corner (SouthEast), but there are more options (NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast).
This task is resolved with this simple CLI instruction:

for i in $(ls ~/Pictures/Lake/*.jpg); do echo ${i}; gm composite -gravity SouthEast ~/Pictures/sign.png ${i} "$(dirname ${i})/Signed/$(basename ${i})"; done

Of course, if your directory is different, you will have to modify the CLI instruction above.

Here is the result:
Without my watermark
With my watermark

If this post may be useful to you, please "Like" it and share it. If people "Like" it, I may show how I did my watermark using Gimp.

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