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Allowing use of GraphicsMagick as conversion tool #3

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Allowing use of GraphicsMagick as conversion tool #3

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b06ad52
moving original to compare with outside of loop
Aug 5, 2016
9fdc9c6
option added to allow use of GraphicsMagick for png conversion
Aug 5, 2016
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24 changes: 19 additions & 5 deletions cjpeg-dssim
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
#
# Required tools:
# * ImageMagick >= v.6
# * GraphicsMagick (alternative to ImageMagick)
# * dssim - https://github.com/pornel/dssim
# * jpegoptim - https://github.com/tjko/jpegoptim
# * mozjpeg - https://github.com/mozilla/mozjpeg
Expand Down Expand Up @@ -47,6 +48,8 @@ else
exit 1
fi

IMAGE_PROCESSOR="$3"

# Path and filename retrieval to save the output image
CLEANFILENAME=${INPUTFILE%.jp*g}
FILEEXTENSION=${INPUTFILE##*.}
Expand Down Expand Up @@ -84,6 +87,7 @@ OUTPUTFILESUFFIX="_cjpeg_dssim"

main () {
define_encoder_toolbelt
define_conversion_tool
local -i __current_jpeg_quality=$(optimize_quality_level ${INITIAL_JPEG_QUALITY} ${JPEG_QUALITY_SUMMAND_SUBTRAHEND})
$(eval ${JPEG_COMPRESSION_COMMAND} > "${CLEANPATH}${CLEANFILENAME##*/}${OUTPUTFILESUFFIX}".${FILEEXTENSION});
}
Expand All @@ -103,11 +107,24 @@ function define_encoder_toolbelt () {
esac
}

function define_conversion_tool () {
# Define conversion tool
case ${IMAGE_PROCESSOR} in
"gmagick") CONVERSION_COMMAND="gm convert";;
"imagick") ;&
"") CONVERSION_COMMAND="convert";;
*) echo "Supported JPEG conversion methods: imagick | gmagick"; exit 1;;
esac
}

function optimize_quality_level () {
local -i __current_jpeg_quality=$1
local -i __current_jpeg_quality_summand_subtrahend=$2
local -i __iteration_counter="0"
local __current_dssim_score="0"
# Convert the original JPEG to PNG for DSSIM comparison
# Also base64 it so we can safely store its result in a variable without needing to write the file to disk
__original_image_png_base64=$(${CONVERSION_COMMAND} "${INPUTFILE}" png:- | base64)
# While the result of the current run is either too similar (ecouraging stronger compression) or too different (already too many artifacts visible), run the compression again while homing in on a proper quality setting for the current encoder
while ( (( $(echo "${__current_dssim_score} >= ${DSSIM_UPPER_BOUND}" | bc -l) )) || (( $(echo "${__current_dssim_score} < ${DSSIM_LOWER_BOUND}" | bc -l) )) ) && (( ${__iteration_counter}<7 )); do
# Retrieve the current dissimilarity score
Expand All @@ -132,12 +149,9 @@ function optimize_quality_level () {

function calculate_dissimilarity () {
local __current_jpeg_quality=$1
# Convert the original JPEG to PNG for DSSIM comparison
# Also base64 it so we can safely store its result in a variable without needing to write the file to disk
local __original_image_png_base64=$(convert "${INPUTFILE}" png:- | base64)
# Run the JPEG compressor, pipe its output to convert, create a PNG from the newly compressed JPEG and hand it to DSSIM for comparison - all without creating a file on disk to increase runtime performance
local __current_dissimilarity=$(eval ${JPEG_COMPRESSION_COMMAND} | convert - png:- | dssim <(echo "${__original_image_png_base64}" | base64 --decode) /dev/stdin | awk '{print $1}')
local __current_dissimilarity=$(eval ${JPEG_COMPRESSION_COMMAND} | ${CONVERSION_COMMAND} - png:- | dssim <(echo "${__original_image_png_base64}" | base64 --decode) /dev/stdin | awk '{print $1}')
echo ${__current_dissimilarity}
}

main
main