Script to make HDRs with Linux

Este artículo también está disponible en Español: Un script para hacer HDR en Linux.

In my article HDR and Linux I explained my current work-flow to make HDRs using Linux. Still on that subject, in this article I show a script I wrote to make all that process automatic with a single call.

The source code for such script is:

#! /bin/bash

set -e

SELF=`basename $0`

DIR=.
ALIGN=N
ENFUSE=N
TONEMAP=N

echo "$SELF: `date`"

while [ "$1" != "" ]; do
 case "$1" in
  "-a")
   ALIGN=Y
   ;;
  "-e")
   ENFUSE=Y
   ;;
  "-t")
   TONEMAP=Y
   ;;
  "-d")
   DIR="$2"
   shift
   ;;
  *)
   echo "$SELF: Parameters"
   echo "$SELF:  -d      -> Directory"
   echo "$SELF:  -a      -> Align images"
   echo "$SELF:  -e      -> Create enfuse"
   echo "$SELF:  -t      -> Create and tonemap HDR"
   exit
   ;;
 esac

 shift
done

HDR="$DIR"/HDR
FILES=("$DIR"/*.[Cc][Rr]2)
COUNT=${#FILES[@]}

echo "$SELF: Options:"
echo "$SELF:  Directory  = $DIR"
echo "$SELF:  Output     = $HDR"
echo "$SELF:  Align      = $ALIGN"
echo "$SELF:  Enfuse     = $ENFUSE"
echo "$SELF:  Tonemap    = $TONEMAP"
echo "$SELF:  Files      = ${FILES[*]}"

if [ $COUNT -eq 0 ]; then
 echo "$SELF: No files found!!!"
 exit 1
fi

echo "$SELF: Creating output directory:"
mkdir "$HDR"

echo "$SELF: Parsing EXIF information:"
dcraw2hdrgen ${FILES[*]} > "$HDR"/pfs_raw.hdrgen

echo "$SELF: Generating TIFFs"
ufraw-batch --wb=camera --gamma=0.45 --linearity=0.10 --exposure=0.0 --saturation=1.0 --out-type=tiff --out-depth=16 --overwrite --out-path="$HDR" ${FILES[*]}

FILES=("$HDR"/*.tif)

if [ "$ALIGN" = "Y" -a $COUNT -gt 1 ]; then
 echo "$SELF: Aligning images"
 align_image_stack -a "$HDR"/AIS_ ${FILES[*]} > "$HDR"/align_image_stack.log
 rm -f ${FILES[*]}
 FILES=("$HDR"/AIS_*.tif)
fi

if [ "$ENFUSE" = "Y" ]; then
 if [ $COUNT -gt 1 ]; then
  echo "$SELF: Generating enfuse:"
  enfuse -o "$HDR"/enfuse.tif ${FILES[*]} > "$HDR"/enfuse.log
 else
  echo "$SELF: By-passing enfuse:"
  ln ${FILES[*]} "$HDR"/enfuse.tif
 fi
fi

if [ "$TONEMAP" = "Y" ]; then
 echo "$SELF: Parsing hdrgen"
 i=0
 > "$HDR"/pfs_tif.hdrgen
 cat "$HDR"/pfs_raw.hdrgen | while read LINE; do
  echo "${FILES[$i]} $LINE" | cut -d' ' -f1,3- >> "$HDR"/pfs_tif.hdrgen
  i=`expr $i + 1`
 done

 echo "$SELF: Generating HDR:"
 pfsinhdrgen "$HDR"/pfs_tif.hdrgen | pfshdrcalibrate -b 16 -x | pfsout "$HDR"/pfs.hdr

 echo "$SELF: Tone-mapping HDR:"

 echo "$SELF:  Operator = mantiuk06"
 pfsin "$HDR"/pfs.hdr | pfstmo_mantiuk06 -e 1 -s 1 | pfsgamma -g 2.2 | pfsoutimgmagick "$HDR"/pfstmo_mantiuk06.tif

 echo "$SELF:  Operator = fattal02"
 pfsin "$HDR"/pfs.hdr | pfstmo_fattal02 -s 1 | pfsoutimgmagick "$HDR"/pfstmo_fattal02.tif
fi

echo "$SELF: Cleanning:"
rm -f ${FILES[*]}

This script was made to be used with the RAW files generated by a Canon 400D camera, but I think it can be easily adapted to other cameras. Specifically, at "FILES=("$DIR"/*.[Cc][Rr]2)" we are selecting files with "CR2" extension, used by Canon (Nikon generates "NEF" files, by example); and the parameters "--gamma=0.45 --linearity=0.10" passed to "ufraw-batch" are specific of a 400D. I think that the rest should be generic.

First of all, we must download that code to our computer and save in into a file that we can execute. I suppose that the easiest way is to enter as the "root" superuser and create a file named "hdr.sh" inside the "/usr/local/bin/" directory. Then select and copy the code from this page, paste it into the file, and save it; finally, give execute permissions to everyone, with "chmod +x /usr/local/bin/hdr.sh" from the command line.

To use this script, we must first unload all the exposures from the same scene into an empty directory. Then execute the script with "hdr.sh -d _directory_ -a -e -t". We wait patiently for a while, and when the script ends there will be three new files inside our directory: "enfuse.tif", "pfstmo_mantiuk06.tif", and "pfstmo_fattal02.tif".

The "-a" parameter aligns the images; if the photos where made using a tripod, and we are completely sure that they are perfectly aligned, we can drop it and the script will be faster. With "-e" we indicate that an enfuse version must be generated, and we can drop it too; moreover, without "-t" the tone-mapped version will not be produced.

Notes

2009/07/27: I have updated this script, to enhance the tonemapping step, using parameters that produce a better result; it can also produce HDRs from a single shot.

2009/09/21: Vincent Tassy has posted an enhancement to this script; his version automatically creates the GIMP file at the end of the process (that is a nice addition), and can also do HDRs from JPEG files (I always shot RAW, never JPEG). Go there and grab his version, it is better than mine: Linux script to generate HDR images from bracketed images.

2009/07/27: Thanks to the help of an anonymous reader, the outputs from the tone-mapping step are now TIFF files; I hope this will improve the quality of the final image.

2011/01/20: The script uses "pfshdrcalibrate -b 16 -x" during the generation of the HDR file; the results are now much better.