Script loops over image filename(s) passes as an argument, upscaling it to 144 dpi using sips. It uses sips again to get the new width and height of the image, and renames the file to include the width, height, and "@2x" in the filename.

scale-and-rename-image.sh

#!/bin/zsh
# Plugin:       Scale and Rename Image
# Description:  upscales an image to 144 dpi and renames the file to append the dimmensions.
# Author:       Jack-Daniyel Strong <[email protected]>
# Date:         11-May-2023
# Version:      0.1
# ==============================================================================

if [ $# -eq 0 ]; then
    echo "No arguments provided. Please provide image file(s) as arguments."
    exit 1
fi

# Loop through image(s) passed
for image in "$@"; do
    # Check if file exists and has a known file extension
    if [[ -f $image && $image =~ \.(jpg|jpeg|png|gif)$ ]]; then
        # Upscale the image to 144 dpi
        /usr/bin/sips -s dpiHeight 144.0 -s dpiWidth 144.0 $image

        # Get the new width and height
        width=$(/usr/bin/sips -g pixelWidth $image | tail -n 1 | cut -d" " -f4)
        height=$(/usr/bin/sips -g pixelHeight $image | tail -n 1 | cut -d" " -f4)

        # Extract directory, base name and extension
        directory=$(dirname "$image")
        base_name=$(basename "$image" | cut -d. -f1)
        extension="${image##*.}"
        # Rename the file
        mv "$image" "${directory}/${base_name}-${width}x${height}@2x.$extension"

        echo "Processed $image"
    else
        echo "File $image not found."
    fi
done