misc/jpeg-if-not-alpha.sh

   1 #!/bin/sh
   2
   3 set -e
   4
   5 : ${qual:=95}
   6
   7 for X in "$@"; do
   8         case "$X" in
   9                 *.jpg)
  10                         jpegoptim --strip-all -m$qual "$X"
  11                         ;;
  12                 *.png|*.tga)
  13                         if convert "$X" -depth 16 RGBA:- | perl -e 'local $/ = \8; while(<>) { substr($_, 6, 2) eq "\xFF\xFF" or exit 1; ++$pix; } END { exit not $pix; }'; then
  14                                 echo "$X has no alpha, converting"
  15                                 convert "$X" -quality 100 "${X%.*}.jpg"
  16                                 jpegoptim --strip-all -m$qual "${X%.*}.jpg"
  17                                 rm -f "$X"
  18                         else
  19                                 echo "$X has alpha, not converting"
  20                         fi
  21                         ;;
  22         esac
  23 done