--- src/jpeg2hdrgen.orig	2006-08-22 18:34:04.000000000 +0000
+++ src/jpeg2hdrgen	2014-06-18 15:27:14.288956550 +0000
@@ -28,53 +28,105 @@
 export LC_ALL
 
 
-JHEAD="jhead"                   # program for extracting exif info from jpegs
-
-TEST_JHEAD=`which jhead`;
-if [ "$TEST_JHEAD" = "" ]; then
-    echo "Program 'jhead' is required to run this script."
-    echo "Install appropriate software, for example from:"
-    echo "http://www.sentex.net/~mwandel/jhead/"
-    exit 1;
-fi
-
-#Note: Double backslash MUST be put in front of each $ sign
-AWK_PROGRAM=`cat <<EOF
+AWK_PROGRAM_COMMON='
 BEGIN {
   exposure="";
   aperture="";
 }
 
 END {
-  if( aperture=="" )
+  if (aperture=="")
     aperture=1;
 
-  if( iso_speed=="" )
+  if (iso_speed=="")
     iso_speed=100;
     
-  if( exposure=="" )
+  if (exposure=="")
     printf("not recognized exif header!\n");
   else
     print exposure " " aperture " " iso_speed " 0";
 }
 
+'
+## jhead output
+AWK_PROGRAM_JHEAD='
 /^Exposure time: ([0-9]*\.[0-9]) */ {
-  exposure = 1/\\$3;
+  exposure = 1/$3;
+  next;
 }
-
 /^Aperture *: f\/([0-9]*\.[0-9]*)/ {
-  aperture = substr(\\$3,3);
+  aperture = substr($3,3);
+  next;
 }
-
 /^ISO equiv. *: ([0-9]*\.?[0-9]*)/ {
-  iso_speed = \\$4;
+  iso_speed = $4;
+  next;
+}'
+
+## exif output
+AWK_PROGRAM_EXIF='
+/^Exposure Time *\|.+ sec\./ {
+  if (split(substr($3,2),a,"/") == 2)
+    exposure = a[2];
+  else
+    exposure = 1/a[1];
+  next;
 }
+/^FNumber *\|f\/.+/ {
+  aperture = substr($2,4);
+  next;
+}
+/^ISO Speed Ratings *\|.+/ {
+  iso_speed = substr($4,2);
+  next;
+}'
+
+## exiv2 output
+AWK_PROGRAM_EXIV2='
+/^ExposureTime *.+/ {
+  if (split($2,a,"/") == 2)
+    exposure = a[2]/a[1];
+  next;
+}
+/^FNumber *.+/ {
+  if (split($2,a,"/") == 2)
+    aperture = a[1]/a[2];
+  next;
+}
+/^ISOSpeedRatings *.+/ {
+  iso_speed = $2;
+  next;
+}'
+
+JHEAD='jhead'                   # program for extracting exif info from jpegs
+EXIV2='exiv2'                   # another one
+EXIF='exif'                     # and one more
+
+if which ${JHEAD} >/dev/null
+then
+    CMD="$(which ${JHEAD})"
+    AWK_PROGRAM="${AWK_PROGRAM_COMMON}${AWK_PROGRAM_JHEAD}"
+elif which ${EXIV2} >/dev/null
+then
+    CMD="$(which ${EXIV2}) -P nv pr"
+    AWK_PROGRAM="${AWK_PROGRAM_COMMON}${AWK_PROGRAM_EXIV2}"
+elif which ${EXIF} >/dev/null
+then
+    CMD="$(which ${EXIF})"
+    AWK_PROGRAM="${AWK_PROGRAM_COMMON}${AWK_PROGRAM_EXIF}"
+else
+    cat <<MSG
+One of the following commands are required to run this script:
+ '${JHEAD}' - stand-alone program (http://www.sentex.net/~mwandel/jhead/)
+ '${EXIV2}' - part of exiv2 project (http://www.exiv2.org/)
+ '${EXIF}'  - part of libexif project (http://sf.net/projects/libexif/)
+MSG
+    exit 1;
+fi
 
-EOF`
-
-while [ "$1" != "" ]; do
-    EXPOSURE_INFO=`$JHEAD $1 | awk "$AWK_PROGRAM"`
-    echo $1 $EXPOSURE_INFO
-
+while [ ${#} -ne 0 ]
+do
+    printf "${1} "
+    ${CMD} "${1}" | awk "${AWK_PROGRAM}"
     shift
-done 
+done