Backlit Moon – RawTherapee and Exposure Fusion

Introduction:
The header photo isn’t very good. It’s been edited to make it clear what this article is about. So, it’s not the final result we’re aiming for. Also, the editing was done using RawTherapee and Showfoto, but you could use other photo editing programs too. RawTherapee was used for adjusting the exposure, while Showfoto has similar Exposure Fusion options like Digikam, Hugin, Enfuse, etc.

How It Started on February 13, 2024:
“Yesterday, around 8:30 p.m., the sky was quite clear. My partner called me outside because the moon looked very special. Indeed, the moon was in its first quarter, but you could see the whole sphere as if it was lit from behind – but more on that in a new article later.”
[Link to original article]

So, that’s what it was about – I’m not even sure if my term “backlit moon” is correct, but it’s definitely not “moon aura,” which is a bright ring around the moon. Anyway, it describes what I saw then. It wasn’t the first time I’d seen something like that, and I’ve tried taking photos of it before – including that day.

Updated : In the meantime, a good friend explained to me what it really is:
It is the New Moon, and the effect is due to sunlight that is reflected from the earth to the moon and then reflected back.
This light is best visible about 3 to 4 days before and after the new moon, when the moon is above and the sun is below the horizon.
Thanks Jan!

What I’ve noticed is that I come across a lot of “Moon Aura” photos taken by other photographers, but a “Backlit Moon” is quite rare. This confirms that capturing such an image isn’t as simple, even though the final solution may appear straightforward.

I took photos with different exposure settings, but either you see that ring around the moon and the visible part is totally overexposed, or the moon’s exposure is correct and the ring disappears. I knew I could fix this with RawTherapee and Exposure Fusion.

Exposure Fusion is also known as Exposure Blending, Blend Stacked Images etc…, the reason why I call it different here is because the purpose is different.
Blend Stacked Images is also used for macro shots, to merge photos with different sharpness settings into one photo with a larger sharpness range – while Exposure Fusion combines different exposures. The tool used with various software is Enfuse.

The only problem for people who feel less comfortable with computers is that Enfuse is command line controlled. That means you have to type text line commands like in the old DOS era.
Not that it is difficult, but it is less user-friendly.
That is why it is easier to use a program such as Digikam, ShowFoto, … so that you can do this from a graphical user interface.

HDR and Enfuse:
While Enfuse and the Fusion or Blending technique can be used to merge images with different exposure settings, for macro images to merge different focus settings, and also for creating HDR. It can also be used to solve a common problem with HDR.
When creating (extreme) HDRs, artifacts sometimes occur, and what many do not know is that Enfuse can also be used here. The simplest solution is to combine HDR images with normally exposed images, the fusion of the two gives an HDR without artifacts.

Basic Method :

First, I used Rawtherapee to create three different TIFF files from an original ‘well exposed’ RAW file using various settings.

1. neutral
2. Adjustment in Shadows/Highlights -> Boost Shadows
3. Contrast Adjustment & Exposure to make sphere more visible

I merged those three pictures together using a feature called Exposure Fusion in Showfoto, which is also known as Blend Stacked Images. This created a single new TIF file. You can find the settings I used for the fusion below, and I didn’t change anything else.

1. Automatic Local/Global Image Features Balance = on
2. Well-Exposedness Contribution = 1.0
3. High-Saturation Contribution = 0.25
4. High-Contrast Contribution = 0.25

Exposure Fusion in Showfoto :

Then I loaded it again in RawTherapee, made some small changes to the exposure, and tried to remove as much noise as possible, then sharpened it slightly.

Result with three photos merged, maybe less clear on the internet, but very clear on my own computer.

By combining more photos and enhancing shadows aggressively while suppressing highlights, you get a more extreme result. It might not look as aesthetically pleasing, but it’s clearer. The best outcome probably lies somewhere between the top and bottom photos. The editing process described here will assist you in achieving that ideal blend.

Have fun with your own backlit moon project !

Download Links and Info :

Enfuse-Enblend : https://enblend.sourceforge.net/enfuse.doc/enfuse_4.2.xhtml/enfuse.html

Enfuse on Ubuntu : https://howtoinstall.co/es/enfuse

DigiKam : https://www.digikam.org/

ShowFoto : https://apps.kde.org/showfoto/

Pat David – info about using Enfuse : https://patdavid.net/2013/07/automatic-exposure-blending-with-enfuse/

La Gallerie

The photo gallery of Open Source Photography, Olympus micro 4/3 system, Vintage Lens Photograpy, Film Simulation, PictureFX, HDR – Photographer : Marc R.