使用命令缩放、压缩图片，工具包括： convert, mogrify, pngcrush, optipng, jpegoptim, trimage, gimp

sudo pacman -S imagemagick

convert origin.jpg --resize 20% -quality 70 result.jpg

identify your-image.jpg

#!/bin/sh
identify=/usr/bin/identify
scale=$1
image=$2   # needs input validation code

height=$($identify $image | cut -d\   -f3 | cut -dx -f1)
width=$($identify $image | cut -d\   -f3 | cut -dx -f2)
newwidth="$(echo $width \* $scale | bc | cut -d. -f1)"
newheight="$(echo $height \* $scale | bc | cut -d. -f1)"
echo "<img src=$image height=$newheight width=$newwidth>"
exit 0

$ scaledown.sh 0.5 pvp.jpg
<img src=pvp.jpg height=152 width=485>

#!/bin/sh
convert=/usr/bin/convert
identify=/usr/bin/identify
resize=$1
source=$2
if [ -z "$resize" -o -z "$source" ] ; then
  echo "Usage: $0 resize sourcefile"; ;exit 1
fi
if [ ! -r $source ] ; then
  echo "Error: can't read source file $source" ; exit 1
fi
# let's grab the filename suffix
filetype=$(echo $source | rev | cut -d. -f1 | rev)
 
tempfile="resize.$filetype" # temp file name

# create the newly sized temp version of the image
$convert $source -resize $resize $tempfile

# figure out geometry, the assemble new filename
geometry=$($identify $tempfile | cut -d\   -f3 )

newfilebase=$(echo $source | sed "s/$filetype//")
newfilename=$newfilebase$geometry.$filetype

# rename temp file and we're done
mv $tempfile $newfilename

echo \*\* resized $source to new size $resize. result = $newfilename

exit 0

sh resize.sh 50% pvp.jpg
** resized pvp.jpg to new size 50%. result = pvp.485x153.jpg

sudo apt-get install jpegoptim
jpegoptim your-target.jpg

sudo pacman -S optipng
optipng gfg.png