How to add watermarks to images via command line – Hopefully using Irfanview

I recommend using ImageMagick, which is open source and quite standard for manipulating images on the command line.

Watermarking with an image is as simple as

composite -dissolve 30% -gravity south watermark.jpg input-file.jpg output-file.jpg

With text, it’s a little more complicated but possible.

Using the above command as an example, a Bash command for doing this to all files in folder would be:

for pic in *.jpg; do
    composite -dissolve 30% -gravity south watermark.jpg $pic ${pic//.jpg}-marked.jpg
done

For more information about watermarking with ImageMagick, see ImageMagick v6 Examples.