A few weeks ago I finally realized my old wish: I bought a real camera for me: a Nikon D40 – which is, according to many, many people, is the best DSLR out there. At least for non-professionals.
With just a few pictures it was already possible to note the difference – I could not ever EVER got close to those pictures with all my previous cameras (like Nokia N95 and Sony CyberShot W90):
However, after a few days with my new camera, I found out that it came with some dust on its sensor. Not much, but clearly visible on pictures with uniform colors (like sky or white wall). For example, it is possible to see the dust spot on the left half of the following picture – if you zoom in, you’ll clearly see that there is some dark spot covering part of a cloud and appearing in the sky:
One could say ‘Ahh, but that is just a small tiny spot.. nobody will notice it’. But… I do notice it, and I don’t like it. So I started looking for solutions for this issue.
In first place, I tried cleaning the sensor using a air blower (without luck). The dust spot moved a bit with the air flow (a few microns) and landed to its new place (permanently, I afraid). The next step was to ask the official Nikon support in Brazil, which is located in São Paulo city, about 250km from where I live. Their answer was is that the sensor cleaning should cost around R$ 100 (about 60 US$) + shipping. Quite expensive in my opinion.
So the next step was to start thinking like a computer geek. The photo is digital, so it is nothing more than a bunch of bits 
. So there SHOULD be some software or at least algorithm suitable for cleaning this all. After a quick research, I found that there is the Nikon Capture NX software which removes the dust pretty well. However, it is
- commercial
- expensive
- orders you to take photos in RAW only. I like RAW, but… the memory card is not infinite.
So another option was to clean the dust in gimp. Manually… and it is needless to say that this approach is.. well.. boring, time-consuming and pretty much futile.
However, when all the hope was, apparently, lost, the Great Google Gods sent me a wonderful link to the Resynthesizer plugin – which is AMAZINGLY EFFICIENT in solving the dust issues.
So, dear readers, without other words, I’ll show you the few needed steps to fix the dust on your photos:
Install resynthesizer plugin. On Mandriva systems, you can cheat and run a magic urpmi gimp2-resynthesizer command which will do the trick. On other systems, go to the resynthesizer web site, download, compile and install the plugin. it is trivial, so I won’t go into additional details here.
Grab your dust-damaged image and open it in gimp. As you can see, there is a horrible dust on the left part of the otherwise-blue sky:
Gimp with the dust-cleaning victim
- Select a region around the dust to remove:
Selecting the dust to remove
- Press CTRL-X to remove the selected area:
Removing the dust
- Now, select a bit larger region around the white spot:
Selecting some space around the dust spot
- Go to Filters->Map->Resynthesize and run the Resynthesize filter:
The Resynthesizer plugin in all its glory
- Wait, wait, and…:
Magic!
- That’s it!:
A perfect clear sky!
Of course, it all could be done manually in gimp. However, the Resynthesizer plugin just makes it easier and better.
So what is the result? A bit more magic + some Hugin hacking and…:
Yes, that’s right. Every image on panorama had a dust spot, which I cleared up with Resynthesizer. So next time you encounter some dust on your photo, remember that there is a GREAT open-source plugin for gimp out there to help!
Enjoy, and have a Happy New Year!
