This script makes a copy of images, resizes the copied images and renames the copied images with the correct width and height. The information gets the script from sips.

resize-rename-sips-information.sh

#!/bin/bash
#
#   1. This script copies all *.jpg-files to a new folder
#   2. Jumps into folder and resizes all files with sips
#   3. Renames all files and uses information from sips
#
folder="processed"
height="320"
width="160" # not used

mkdir -p "$folder"

cp *.jpg "$folder"

cd "$folder"

# RESIZE ALL IMAGES TO MAXIMUM HEIGHT OF $height

echo "RESIZE ALL IMAGES WITH MAXIMUM HEIGHT OF $height"
sips --resampleHeight "$height" *.jpg

# RENAME FILES WITH INFORMATION FROM SIPS
for i in *.jpg
  do
    pixelWidth=$(sips -g pixelWidth "$i" | awk '/pixelWidth:/{print $2}')
    pixelHeight=$(sips -g pixelHeight "$i" | awk '/pixelHeight:/{print $2}')
    # REMOVE EXTENSION
    filename=${i%.jpg}
    # NOW RENAME
    mv $i ${filename##*/}-${pixelWidth}x${pixelHeight}.jpg
  done

for i in *.jpg
  do
    echo -e "\x1b[0;33mOptimize $i now with Guetzli"
    guetzli -quality 85 $i $i
    echo -e "\033[32mDone ✓\033[0m"
done