Preparing images with GraphicsMagick

convert_images.md

Resize

gm convert -strip -resize $RESIZE -define jpeg:preserve-settings $INPUT $TMPIMG

Watermark

gm convert -size $(gm identify -format %wx%h $TMPIMG) xc:none -pointsize 12 -font helvetica -gravity southeast -fill "#000" -draw "text 10,10 '$TEXT'" -fill "#fff" -draw "text 11,10 '$TEXT'" png:-

Magick

gm convert -strip -resize $RESIZE -define jpeg:preserve-settings $INPUT $TMPIMG && gm convert -size $(gm identify -format %wx%h $TMPIMG) xc:none -pointsize 12 -font helvetica -gravity southeast -fill "#000" -draw "text 10,10 '$TEXT'" -fill "#fff" -draw "text 11,10 '$TEXT'" png:- | gm composite -dissolve 50 -interlace Line -quality $QUALITY - $TMPIMG $OUTPUT

convert_images.sh

#!/usr/bin/env bash

if [ ! -x $(which gm) ]
then
    echo "GraphicsMagick is required."
    exit 1
fi

TMPDIR=$(mktemp -d)
OUTDIR=../output

[ -d $OUTDIR ] || mkdir $OUTDIR

for file in *
do
    INPUT="$file"
    TMPIMG="$TMPDIR/$INPUT"

    _FILE="${INPUT//-/_}"
    _FILE="${_FILE,,}"
    _FILE="${_FILE//.jpeg/.jpg}"

    OUTPUT="$OUTDIR/$_FILE"

    gm convert -strip -resize $RESIZE -define jpeg:preserve-settings $INPUT $TMPIMG
    gm convert -size $(gm identify -format %wx%h $TMPIMG) xc:none \
        -pointsize 18 \
        -font helvetica \
        -gravity southeast \
        -fill "#000" \
        -draw "text 10,10 '$TEXT'" \
        -fill "#fff" \
        -draw "text 11,10 '$TEXT'" png:- | \
        gm composite -dissolve 50 -interlace Line -quality $QUALITY - $TMPIMG $OUTPUT
done

rm -r $TMPDIR