Shell script
Convert to AVIF Programmatically

This shell script converts JPG and PNG images into AVIF and WebP using libavif and Google’s WebP encoder.

# macOS
brew install libavif webp

# Arch Linux
sudo pacman -S libavif webp

For AVIF, it uses a compression of min = 25 and max = 35, which works well for Uxtly’s screenshots (images with text and sharp edges). Besides smaller file sizes, they make optically better images than cwebp. No artifacts, sharper, and more accurate colors.

#!/bin/sh
set -o noglob
IFS=$'\n'

images=$(find ~/imgs -type f -name *.png -o -name *.jpg)

for img in $images; do
  avif_out=$img.avif
  webp_out=$img.webp

  if [ $img -nt $avif_out ]; then
    avifenc --speed 0 --min 25 --max 35 $img $avif_out
  fi

  if [ $img -nt $webp_out ]; then
    cwebp $img -o $webp_out
  fi
done

The images end up with the original extension plus the modern one (e.g. foo.png.avif) because I need those file names to Conditionally Serve the Optimal Image Format with Nginx.