Watermark Images in Thunar File Manager

The Bash Script

#!/bin/bash
# Requires jpegoptim, imagemagick.
#
# Example usage: bash ~/bin/watermark.sh input.png '~/watermark.png'
#
# Thunar Action Setup
#
# Command: bash ~/bin/watermark.sh %n '/path-to/watermark.png'
# Use Startup Notification: Checked
# Appearance Conditions
# File Pattern: *
# Appears if selection contains: Image Files 

set -ex

# Input filename and extension
FILE="$1"
EXTENSION="${FILE##*.}"  # Extract extension from filename

# Input filename without extension
NAME="${FILE%.*}"

# Watermark image file
WATERMARK_IMAGE="$2"

# Target image size for resizing
IMAGE_SIZE='1000x1000'

# Construct a unique name with date and time
NAME_DATE=$(basename "${NAME}")_$(date +"%d%m%Y%S")

# Copy the original file to a new name with the determined extension
cp "${FILE}" "${NAME_DATE}.${EXTENSION}"

# Resize the copied image
convert "${NAME_DATE}.${EXTENSION}" -resize "${IMAGE_SIZE}" -flatten "${NAME_DATE}.${EXTENSION}"

# Apply watermark
convert "${NAME_DATE}.${EXTENSION}" "${WATERMARK_IMAGE}" -gravity center -compose over -composite "${NAME_DATE}.jpg"

# Optimise JPEG quality
jpegoptim -s -m 90 "${NAME_DATE}.jpg"

# Remove the intermediate processed file
if [ "${EXTENSION,,}" != "jpg" ]; then
	rm "${NAME_DATE}.${EXTENSION}"
fi

exit

The examples on this page use the bin directory within the user’s Home directory. Home -> User -> bin. Place the script in the bin folder.