A Bash script to resize and optimize images in a directory (optionally recursively), supporting PNG, JPEG/JPG, and WebP formats.

squimage.sh

#!/bin/bash

# PREFLIGHT
# sudo apt update && sudo apt install -y imagemagick optipng jpegoptim webp tar findutils

set -euo pipefail

# ----------------------------
# Defaults
# ----------------------------
DIR=""
RECURSIVE=false
RESIZE=""
MIN_SIZE=""
BACKUP=false

# ----------------------------
# Requirements
# ----------------------------
need() {
  command -v "$1" >/dev/null 2>&1 || {
    echo "Missing required tool: $1" >&2
    exit 1
  }
}

need find
need tar
need optipng
need jpegoptim
need cwebp
need mogrify

# ----------------------------
# Usage
# ----------------------------
usage() {
  cat <<EOF
Usage:
  $0 -D DIR [options]

Options:
  -r              Include subdirectories
  -d WxH          Resize to max width/height before optimizing (e.g. 1920x1080)
  -s SIZE         Minimum file size to consider (e.g. 300k, 1M)
  -b              Create backup tar.gz before modifying files
  -h              Show this help

Examples:
  $0 -d images
  $0 -d images -r
  $0 -d images -r -d 1920x1080 -s 300k -b
EOF
  exit 1
}

# ----------------------------
# Parse args
# ----------------------------
while getopts ":D:rd:s:bh" opt; do
  
  case "$opt" in
    D) DIR="$OPTARG" ;;
    r) RECURSIVE=true ;;
    d) RESIZE="$OPTARG" ;;
    s) MIN_SIZE="$OPTARG" ;;
    b) BACKUP=true ;;
    h) usage ;;
    *) usage ;;
  esac
done

[[ -z "$DIR" ]] && usage
[[ ! -d "$DIR" ]] && { echo "Directory not found: $DIR"; exit 1; }

# ----------------------------
# Find depth
# ----------------------------
DEPTH=(-maxdepth 1)
$RECURSIVE && DEPTH=()

# ----------------------------
# Build file list
# ----------------------------
FIND_CMD=(find "$DIR" "${DEPTH[@]}" -type f \( -iname "*.png" -o -iname "*.jpg" -o -iname "*.jpeg" -o -iname "*.webp" \))

[[ -n "$MIN_SIZE" ]] && FIND_CMD+=(-size +"$MIN_SIZE")

mapfile -t FILES < <("${FIND_CMD[@]}")

[[ ${#FILES[@]} -eq 0 ]] && { echo "No images found."; exit 0; }

# ----------------------------
# Backup only affected files
# ----------------------------
if $BACKUP; then
  TS=$(date +"%Y%m%d-%H%M%S")
  TAR="image-backup-$TS.tar.gz"
  echo "Creating backup: $TAR"

  tar -czf "$TAR" --absolute-names "${FILES[@]}"
fi

echo "Processing ${#FILES[@]} images…"
[[ -n "$RESIZE" ]] && echo "Resizing to max: $RESIZE"
$RECURSIVE && echo "Including subdirectories"
[[ -n "$MIN_SIZE" ]] && echo "Only processing files larger than: $MIN_SIZE"

# ----------------------------
# Process images
# ----------------------------
for f in "${FILES[@]}"; do
  echo "→ $f"

  # Resize first (never upscale)
  if [[ -n "$RESIZE" ]]; then
    mogrify -resize "${RESIZE}>" "$f"
  fi

  case "${f,,}" in
    *.png)
      optipng -o7 -strip all "$f" >/dev/null
      ;;
    *.jpg|*.jpeg)
      jpegoptim --all-progressive --max=75 -o -p --strip-all "$f" >/dev/null
      ;;
    *.webp)
      cwebp -q 75 "$f" -o "$f" >/dev/null
      ;;
  esac
done

echo "Done."