johan · March 9, 2012 20:30 · Mar 9, 2012
diff --git a/jpopt.sh b/jpopt.sh
@@ -0,0 +1,61 @@
+#! /bin/sh
+
+# Lossless repacking of JPEG images, to save disk space
+# Keeps EXIF tags and comments on digital camera images, otherwise wipes them
+# Requires the "jhead" program to function properly
+# Keeps file timestamps, or sets file time to EXIF timestamp if present
+# Fredrik Mellström <traal@chalmers.se>, Aug 2005
+
+# Usage examples:
+#      jpopt *.jpg
+#      find . -type f -iname '*.jpg' -print0 | xargs -0 jpopt
+
+siz() { ls -l "$1" | awk '{print $5}'; }
+
+if type jhead >/dev/null 2>&1; then
+    jhead=1 copy=none
+else
+    jhead=  copy=all
+    echo >&2 WARNING: jhead not found, cannot optimize comments or EXIF data
+fi
+
+trap exit 1 2 3 13 15
+oldsum=0  newsum=0
+
+for f do
+    [ -f "$f" ] || { echo >&2 "no file '$f'"; continue; }
+    mydir=`dirname "$f"`
+    [ "$mydir" -a -d "$mydir" ] || { echo >&2 "no dir '$mydir'"; continue; }
+    a=$mydir/_${$}_a.jpg  b=$mydir/_${$}_b.jpg
+    trap 'rm -f "$a" "$b"' 0
+    rm -f "$a" "$b"
+
+    printf "'%s' ... " "$f"
+    jpegtran -copy "$copy" -opt  "$f" >"$a" 2>/dev/null && touch -r "$f" "$a"
+    jpegtran -copy "$copy" -prog "$f" >"$b" 2>/dev/null && touch -r "$f" "$b"
+    [ -f "$a" -a -s "$a" -a -f "$b" -a -s "$b" ] ||
+	{ rm -f "$a" "$b"; trap 0; echo FAILED; continue; }
+    [ "$jhead" ] && jhead "$f" 2>/dev/null | grep '^Camera ' >/dev/null && {
+	[ -f "$a" ] && jhead -te "$f" -dt -ft "$a" >/dev/null 2>&1 &&
+	[ -f "$b" ] && jhead -te "$f" -dt -ft "$b" >/dev/null 2>&1 &&
+	printf 'exif ' ||
+	    { rm -f "$a" "$b"; trap 0; echo EXIF_FAILED; continue; }
+    }
+
+    oldsize=`siz "$f"`   optsize=`siz "$a"`     progsize=`siz "$b"`
+    if [ $progsize -lt $oldsize -a $progsize -lt $optsize ]; then
+	mv -f "$b" "$f"
+	printf prog
+    elif [ $optsize -lt $oldsize ]; then
+	mv -f "$a" "$f"
+	printf opt
+    fi
+    rm -f "$a" "$b"; trap 0; echo
+    oldsum=`expr $oldsum + $oldsize`
+    oldsize=`siz "$f"`
+    newsum=`expr $newsum + $oldsize`
+done
+
+[ $oldsum -gt 0 -a $newsum -gt 0 ] &&
+    echo $oldsum bytes total, saved `expr $oldsum - $newsum` bytes \
+    \(`expr 100 \* \( $oldsum - $newsum \) / $oldsum`%\)