利用 ImageMagick 壓縮圖片

imageCompress.sh

#!/bin/bash
# version 1.3.2
# Rex Tsou
# 2017/01/09

echo --------------------
echo 圖片壓縮工具 v1.3.2
echo Author: Rex Tsou
echo --------------------

# ==============================================

function resize(){
	# ${1} = width(px)
	# ${2} = height(px)
	magick ${img} -resize ${1} -gravity center -crop ${1}x${2}+0+0 +repage output/${img%.jpg}.jpg
}

function compress(){
	# ${1} = maxium file size(kb)
	magick ${img} -strip -interlace Plane -define jpeg:extent=${1}kb ${img}
}

function resize_cli(){
	read -r -p "確定要製作縮圖？ [y/N] " response
	response=${response,,}    # tolower
	if [[ $response =~ ^(yes|y)$ ]]
	then
		mkdir -p output
		read -p "請指定輸出寬度（px） " width
		read -p "請指定輸出高度（px） " height
		
		for img in $(find -type f -name "*.jpg" -printf '%P\n');
		do
			# echo $img >> list.txt
			resize ${width} ${height}
		done
	else
		exit 1
	fi
}

function compress_cli(){
	read -r -p "要壓縮圖片嗎？ [y/N] " response
	response=${response,,} # tolower
	if [[ $response =~ ^(yes|y)$ ]]
	then
		read -p "要壓縮成__kb？(輸入數字即可) " compressed
		for img in $(find -type f -name "*.jpg" -printf '%P\n' | grep output/);
		do
			compress ${compressed}
		done
	else
		exit 1
	fi
}

usage="
$(basename "$0") 使用說明：

	-h  使用說明
	-r  調整尺寸
	-c  壓縮圖片

本圖片處理工具，使用 ImageMagick 所提供之命令列介面，使用前須先安裝 imagemagick。
詳細安裝資訊請參考官方網站：https://www.imagemagick.org

"

while getopts ':hrc' option; do
  case "$option" in
    h) echo "$usage"
       exit
       ;;
    r) resize_cli
			 exit
			 ;;
		c) compress_cli
			 exit
			 ;;
    :) printf "missing argument for -%s\n" "$OPTARG" >&2
       echo "$usage" >&2
       exit 1
       ;;
   \?) printf "illegal option: -%s\n" "$OPTARG" >&2
       echo "$usage" >&2
       exit 1
       ;;
  esac
done

# ==============================================

read -r -p "確定要製作縮圖？ [y/N] " response
response=${response,,}    # tolower
if [[ $response =~ ^(yes|y)$ ]]
then
	mkdir -p output
	read -p "請指定輸出寬度（px） " width
	read -p "請指定輸出高度（px） " height
	
	for img in $(find -type f -name "*.jpg" -printf '%P\n');
	do
		# echo $img >> list.txt
		resize ${width} ${height}
	done
else
	exit 1
fi

read -r -p "要順便壓縮嗎？ [y/N] " response
response=${response,,} # tolower
if [[ $response =~ ^(yes|y)$ ]]
then
	read -p "要壓縮成__kb？(輸入數字即可) " compressed
	for img in $(find -type f -name "*.jpg" -printf '%P\n' | grep output/);
	do
		compress ${compressed}
	done
else
	exit 1
fi