How can I batch apply different watermarks for horizontal and vertical pictures in ImageMagick?

Question

How can I mass apply different watermarks (horizontal and vertical) on different images (horizontal and vertical)?

I have folder tree with hundreds of PNG files like this (as example):

modern
classic
balance

I have two watermarks:

watermark-horizontal.png
watermark-vertical.png

How can I apply horizontal watermark on horizontal photos and vertical watermark on vertical photos?

I can do it for a single photo like this:

convert watermark-horizonal.png some-horizontal.png result.png

How can I do the same for many?

Answer 1

Like this:

#!/bin/bash
for f in *.png
do
   read w h <<< $(convert "$f" -ping -format "%w %h" info: )
   if [ $w -gt $h ]; then
      echo "$f is $h tall and $w wide (landscape)"
      convert watermark-horizonal.png "$f" "wm-$f"
   else
      echo "$f is $h tall and $w wide (portrait)"
      convert watermark-vertical.png "$f" "wm-$f"
   fi
done

If you want to recurse, you can do this:

#!/bin/bash
find . -name "*.png" -print0 | while read -d $'\0' f
do
   read w h <<< $(convert "$f" -ping -format "%w %h" info: )
   if [ $w -gt $h ]; then
      echo "$f is $h tall and $w wide (landscape)"
   else
      echo "$f is $h tall and $w wide (portrait)"
   fi
done

Save in a file called go, then type the following in a Terminal

chmod +x go       # Do this just ONCE to make script executable
./go              # Do this any number of times to run it

By the way, I use the following command for my watermarking:

composite -dissolve 50% -resize "1x1<" -gravity center copyright.png x.png x.png