libpng/pngzop

#!/bin/sh

# pngzop

# Copyright 2013 by Glenn Randers-Pehrson
# Released under the pngcrush license (equivalent to the libpng license)

# Extracts the concatenated data from the IDAT chunks in a set of PNG files,
# recompresses them with zopfli, and embeds them in a new set of PNG files
# with suffix ".png" replaced (by default) with "_pngzop.png"

# Requires zopfli, pngcrush (version 1.7.56 or later), zpipe (from the
# zlib-1.2.7 distribution, in the "examples" directory), pngfix (from the
# libpng-1.6.3 or later distribution), and "mkdir -p",
# along with these programs that should have been installed along with
# this "pngzop" script:
#
#        pngzop_get_ihdr.exe
#        pngzop_get_idat.exe
#        pngzop_get_iend.exe
#        pngzop_zlib_to_idat.exe

# Usage:
# pngzop [-b|--brute] [-d|--directory dir] [-e|--extension ext] *.png

# Input: *.png
# Output: *_pngzop.png

brute=
directory=.
extension=

for x in $*
do
case $1 in
  -b|--brute)
    brute=true
    shift;;
  -d|--directory)
    shift
    directory=$1
    shift;;
  -e|--extension)
    shift
    extension=$1
    shift;;
  *)
    break;;
esac
done

# If a directory was defined, don't change filenames (extension == .png)
# unless an extension was also defined.
case x$directory in
    x.)
      ;;
    *)
      case x$extension in
        x)
          extension=.png
          ;;
        *)
          ;;
      esac
      mkdir -p $directory
      ;;
esac

case x$extension in
  x)
    case x$brute in
       xtrue)
         extension=_bzop.png
         ;;
       *)
         extension=_pzop.png
         ;;
       esac
    ;;
  *)
    ;;
esac

case x$brute in
  xtrue)
      for x in $*
      do
        root=`echo $x | sed -e s/.png$//`
        pngzop_get_ihdr.exe < $x > ${root}_pz.png

        # Generate trial PNGs with filter none, 4 PNG filters, and adaptive
        # filter
        for f in 0 1 2 3 4 5
        do
          pngcrush -q -m 1 -f $f -force $x ${root}_f$f.png &
        done
        wait

        # Extract and decompress the zlib datastream from the concatenated
        # IDAT chunks.
        for f in 0 1 2 3 4 5
        do
          pngzop_get_idat.exe < ${root}_f$f.png | zpipe -d > ${root}_f$f.idat &
        done
        wait
        rm -f ${root}_f?.png

        # Recompress the IDAT data using zopfli
        for f in 0 1 2 3 4 5
        do
          zopfli --i25 --zlib ${root}_f$f.idat &
        done
        wait
        rm -f ${root}_f?.idat

        # Copy the smallest result to file.zlib

        file=${root}_f0.idat.zlib
        smallest=$file
        smallsize=`ls -l $file | sed -e "
s/[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
//" -e "s/[ 	].*//"`

        for f in 1 2 3 4 5
        do

        file=${root}_f$f.idat.zlib

        size=`ls -l $file | sed -e "
s/[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
[^ 	]*[	 ]*\
//" -e "s/[ 	].*//"`

        if [ $smallsize -gt $size 	] ; then
        smallest=$file
        smallsize=$size
        fi
        done

        pngzop_zlib_to_idat.exe < $smallest >> ${root}_pz.png
        rm -f ${root}_f?.idat.zlib
        pngzop_get_iend.exe < $x >> ${root}_pz.png

        # Optimize the CMF bytes
        pngfix -o --quiet --out=${directory}/${root}${extension} ${root}_pz.png
        rm ${root}_pz.png

      done
    ;;

  x)
    for x in $*
    do
      root=`echo $x | sed -e s/.png$//`
      pngzop_get_ihdr.exe < $x > ${root}_pz.png

      # Do pngcrush level 9 with none, 4 filters, and adaptive filtering, and
      # select the smallest.
      pngcrush -q -m 113 -m 114 -m 115 -m 116 -m 117 -m 118 \
         -force $x ${root}_L9.png

      # Extract and decompress the zlib datastream from the concatenated
      # IDAT chunks.
      pngzop_get_idat.exe < ${root}_L9.png | zpipe -d > ${root}_L9.idat
      rm ${root}_L9.png

      # Recompress with zopfli and write it on output.
      zopfli --i25 --zlib -c ${root}_L9.idat |
        pngzop_zlib_to_idat.exe >> ${root}_pz.png
      rm ${root}_L9.idat
      pngzop_get_iend.exe < $x >> ${root}_pz.png

      # Optimize the CMF bytes
      pngfix -o --quiet --out=${directory}/${root}${extension} ${root}_pz.png
      rm ${root}_pz.png

      shift
    done
    ;;

esac