In a comment on my previous post about HDR, Felix Hagemann recommended Enfuse as an alternative to HDR. Enfuse doesn’t require to build a “real HDR” image that you tonemap afterwards. Instead it blends together images that are exposed differently – a lot more simple and direct. Let’s see what the results can be and compare them to proper HDR and “mere” RAW processing.
Building Enfuse – the tricky part
Enfuse is part of Enblend and at beta stage. The version of Enblend included in Hardy Heron doesn’t include Enfuse, so compilation, here we go. wiki.panotools.com has a very good and complete howto build Enblend on Ubuntu (and others).
After installing a gazillion dev dependencies, the howto warns that “The second make step can be very long and memory consuming. Make sure you have enough swap space, and go get a healthy snack while the computer is compiling. ”
“Make” actually nearly killed my computer, gobbeling up RAM, filling swap space, everything became irresponsive and after two hours, it was still swapping like mad. So I killed the compilation and restarted it in console mode. 5 minutes later, lo and behold, Enblend was built, including Enfuse. Xorg and the Gnome stack use a bit of resources, apparently…
Since Beka commented in my previous entry about HDR that you can’t do proper HDR without bracketing your shot (ie developping the same RAW file with different exposures doesn’t cut it), I decided to do the proper thing and walked through Geneva armed with my tripod – I felt more embarrassed than pro, if you ask me.
Anyway, I setup my camera to do a bracketing of -2; 0 and +2, using shutter-priority and took a few (semi-)decent shots which I processed with UFRAW standard parameters (no correction).
I then had the 3 files processed by enfuse with a simple:
enfuse -o final_file.jpg file1.jpg file2.jpg file3.jpg
Enfuse prints out a few numbers on the terminal and spits a final_file.jpg which is a blending of the 3 differently exposed files. Here are 2 examples from my “tripod trip”:
The above is in the Parc des Bastions in Geneva, where the Reformation Wall is.
This one is the Jeremiah statue by Rodo that is just next to Geneva Cathedral. I have been fascinated by this statue and never really managed to photograph it in a way that satisfied me, partly because the statue is quite dark (and in the shade) against the clear and sunny Cathedral with luminous sky.
Too much DR for a camera sensor and a perfect test for “enhanced dynamic range” …
HDR (Qtpfsgui) version
Since I had the bracketed images to do a proper HDR, I had a go at it with Qtpfsgui. I won’t bother posting all of the different version for all the different algorithms this time, but here are the versions I prefer from playing with different settings.
For the record, the bastions image uses the Reinhard05 algorithm while Jeremiah is processed with Mantiuk.
What about RAW processing?
Just to make sure I tried everything, I fired Rawstudio and tried to get the best possible outputs from the (correctly exposed) RAW files. Indeed a RAW file has quite some more DR than a JPEG from camera and a good use of the curve tool can give a great output. Here are the results:
I am amazed how many time when shooting “casually” (ie without a tripod) I come across a DR that is beyond what my camera can capture; and I am amazed that I had a hard time finding “large DR” images when walking about with my tripod.
I thought the dark tree trunks vs the sky would be far more DR than what my camera can handle and it wasn’t. Granted, Jeremiah came out pitch dark against the sky background, but again, touching up the shadows did a good job.
A few words of comparison
So what do we end up with? 3 different ways to achieve different results all with the goal to enhance DR. Let’s just sum up what can be learned from this simple experimentation – not a scientific testing…
- Enfuse: quick and easy processing, at least once you have the bracketed shots. Not a great amount of DR gain, though – Jeremiah is pitch black…
- HDR: more complicated processing: bracketed shots, making an HDR file and tonemapping it. Gives an infinite amount of DR but also a funny / weird / special (lovely?) look.
- RAW processing: just one shot and a reasonable amount of post processing. The curves tool gives a great result and if you don’t push it too much, you keep the noise acceptable in the shadow and an overall natural look. Masking can also do wonders, but is a lot more time consuming. However the amount of DR available is limited.
A last word about HDR
I have been giving some more thoughts to this HDR thingie – I even watched Flickr HDR images as a slideshow for a bit, something that I would qualify as “an experience”.
All in all, I would put HDR in the same bag as “‘toshop filters”, I mean “Gimp filters”: if you know what you are doing, if you don’t abuse it and (probably) if you plan your shot with a specific filter in mind, you can achieve great results. If you plan your image for an HDR look, it will look great, like the Cambridge in Color gallery.
But trying to save a so-so image with a water color filter, a solarization filter or with HDR will not save it: it will kill it.