convert-to-srgb

#!/bin/bash
set -eo pipefail

SRGB_ICC_PROFILE=~/.local/share/color/icc/sRGB-IEC61966-2.1.icc

throw() {
  printf '%s: %s\n' "${0##*/}" "$1" >&2
  return 1
}

if [[ $# == 0 || $1 =~ ^(--help|-h)$ ]]; then
  cat >&2 <<EOF
Usage: convert-to-srgb [-a] <images...>

For each input image, if it contains a non-sRGB color profile, extracts the
profile with exiftool (as imagemagick sometimes fails to recognize embedded ICC
profiles) and converts it to sRGB using the ICC profile at:
$SRGB_ICC_PROFILE

Output images are saved as PNGs alongside the inputs, with the original
extension changed to '.srgb.png'.

Options:

  -a    Convert all images to PNG, with the '.srgb.png' suffix, even if they're
        already sRGB or PNG. Useful to avoid separate code paths in scripts.

  -x    Exit with a non-zero exit code if an image does not need converting.
        Mutually exclusive with -a.
EOF
  exit 1
fi

paths=()
all=
fail=
while (( $# > 0 )); do
  case $1 in
    --)
      shift
      paths+=("$@")
      break
      ;;
    -a)
      all=1
      ;;
    -x)
      fail=1
      ;;
    -*)
      throw "unknown option: $1"
      ;;
    *)
      paths+=("$1")
      ;;
  esac
  shift
done

skip() {
  local reason=$1
  local input=$2
  local output=$3
  if [[ ! $all ]]; then
    printf '  %s, skipping.\n' "$reason"
    if [[ $fail ]]; then
      exit 1
    fi
    return
  elif [[ $input == *.png ]]; then
    printf '  %s, copying as-is...\n' "$reason"
    cp "$input" "$output"
  else
    printf '  %s, converting to png...\n' "$reason"
    magick "$input" "$output"
  fi
  printf '  Saved \e[35m%s\e[m\n' "$output"
}

for input in "${paths[@]}"; do

  printf '\e[32m%s\e[m\n' "$input"

  output="${input%.*}.srgb.png"

  # Check for non-sRGB color profile
  profile_desc=$(exiftool -m -b -ICC_Profile:ProfileDescription "$input")
  if [[ $profile_desc ]]; then
    printf '  Color profile: \e[36m%s\e[m\n' "$profile_desc"
    if [[ $profile_desc == sRGB* ]]; then
      skip 'Input already sRGB' "$input" "$output"
      continue
    fi
  else
    skip 'Input does not have an embedded color profile' "$input" "$output"
    continue
  fi

  # Extract embedded ICC profile
  echo '  Extracting color profile...'
  exiftool -q -m -icc_profile -b -w! icc "$input"

  # Convert to sRGB
  echo '  Converting to sRGB...'
  magick "$input" -profile "${input%.*}.icc" -profile "$SRGB_ICC_PROFILE" "$output"
  printf '  Saved \e[35m%s\e[m\n' "$output"

  rm "${input%.*}.icc"

done