Example script for MacOS for converting static images to the webp format

gistfile1.txt

#!/bin/bash
# convert-to-webp.sh
# Converts PNG/JPG/GIF/TIFF/BMP to WebP. Animated GIFs use gif2webp. Does not delete originals. The .webp versions are written alongside them.
# Skips: favicons, SVG, already-WebP files.
# Replace IMG_DIR file path from your project to use this script for your own stuff. This script should work on Linux as well but will need some modification for Windows.

IMG_DIR="${1:-wagtailio/static/img}"
QUALITY=85
METHOD=6

find "$IMG_DIR" -type f \( \
  -name "*.png" -o -name "*.jpg" -o -name "*.jpeg" \
  -o -name "*.gif" -o -name "*.tiff" -o -name "*.tif" \
  -o -name "*.bmp" \
\) ! -path "*/favicons/*" \
| while read -r src; do
    out="${src%.*}.webp"
    echo "Converting: $src → $out"

    src_lower=$(echo "$src" | tr '[:upper:]' '[:lower:]')
    case "$src_lower" in
      *.jpg|*.jpeg)
        cwebp -q $QUALITY -m $METHOD -metadata none "$src" -o "$out"
        ;;
      *.png)
        cwebp -q $QUALITY -m $METHOD -sharp_yuv -alpha_q 90 "$src" -o "$out"
        ;;
      *.gif)
        frames=$(identify -format "%n\n" "$src" 2>/dev/null | head -1)
        if [[ "$frames" -gt 1 ]] 2>/dev/null; then
          gif2webp -q $QUALITY -m $METHOD -mixed -loop_compatibility "$src" -o "$out"
        else
          cwebp -q $QUALITY -m $METHOD "$src" -o "$out"
        fi
        ;;
      *.tiff|*.tif)
        cwebp -q 90 -m $METHOD -metadata none "$src" -o "$out"
        ;;
      *.bmp)
        cwebp -q $QUALITY -m $METHOD -sharp_yuv "$src" -o "$out"
        ;;
    esac
done