Resize Big Pictures in Bulk

run.sh

#!/usr/bin/env bash

CURRENT_DIR=$(pwd)

MAX_SIDE_SIZE=1024  # see also: https://www.imagemagick.org/script/command-line-processing.php#geometry

JPEG_EXTENSION_PRIMARY=jpg
JPEG_CONVERSION_QUALITY=85


resize_JPEG () {
  file_path=$1
  echo "${file_path}"

  # do not specify JPEG quality to avoid new compression
  mogrify \
    -strip \
    -interlace Plane \
    -resize "${MAX_SIDE_SIZE}x${MAX_SIDE_SIZE}"\> \
    "${file_path}"
}


resize_other () {
  file_path=$1
  echo "${file_path}"

  mogrify \
    -strip \
    -interlace Plane \
    -resize "${MAX_SIDE_SIZE}x${MAX_SIDE_SIZE}"\> \
    -format $JPEG_EXTENSION_PRIMARY \
    -quality $JPEG_CONVERSION_QUALITY \
    "${file_path}"

  # delete original file if its extension in lowercase is not $JPEG_EXTENSION_PRIMARY
  file_ext=$(echo "${file_path}" | sed 's/.*\.//' | tr '[:upper:]' '[:lower:]')
  if [[ "$file_ext" != "$JPEG_EXTENSION_PRIMARY" ]]; then
    rm -f "${file_path}";
  fi
}


find "$CURRENT_DIR" -type f -print0 | while IFS= read -r -d $'\0' file_path
do
  file_info=$(file "$file_path" | awk -F: '{ print $2 }')

  if [[ "${file_info}" == *"JPEG"* ]]; then
    resize_JPEG "$file_path";
  elif [[ "${file_info}" == *"image"* ]]; then
    resize_other "$file_path";
  fi
done