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!
Nice explanation!
I fully agree that Resynthesizer is a powerful feature, but I think it could be a bit easier to use like the “Retouch” feature in iPhoto, as can be seen in this example: http://sheldonbarnes.com/blog/?p=347 It would be a lot better
Thanks and congrats!
As said via IRC, simply amazing pano!
Any chance that you could post some of these pictures here: http://forum.mandriva.com/viewtopic.php?t=120792&highlight= They look really great and I am lacking ones for the spring release.
Already installed the plugin, its great for all small objects on the picture. Cheers for the heads up on this.
@Donald Stewart: sure, feel free to use any of them! I think they are under CC copyright, but if you need something even less restrictive, feel free to ask me!
What a drag tho. Why not try to return the camera where you bought it for exchange?
I have a Pentax DSLR K200D, and before that a *ist. I too have been plagued by dust spots. It took a while to learn that it is best to remove the dust before using the camera. The blower I bought just does not blow hard enough (as you have found).
I remove the lens, hold the camera upside down and blow into the hole with all the strength my lungs can create, then wait a few moments for the condensation from my breath to evaporate. Since starting this routine dust spots have disappeared. I am sure that this is not recommended by the manufacturers, but like you I hate spots on my pictures.
I think prevention is better than correction.
ps Do not ever feel the urge to clean the sensor with something like Windex – it will destroy it.
Well, the idea is to fix it, either by exchanging or just cleaning. The problem is that I liked the photos I have taken with this dust, so somehow I had to find a way to fix them.
By googling, I was quite impressed by the number of people plagued with the dust issues – even on new cameras. But that’s life..
[...] Cleaning dust on photos: or “In Gimp We Trust!” 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. [...]
@eugeni “The problem is that I liked the photos I have taken with this dust, so somehow I had to find a way to fix them.”
Cannot agree more, I too have some great photos spoiled by spots and will take your advice and try Resynthesizer.
cheers
[...] gimp – resynthesizer plugin By hpfn limpando a poeira [...]
This is a great article for people that are using linux, or just can’t simply afford Photoshop.
I use a Nikon D60 and the built in sensor cleaner does a pretty good job.
Good Tips and Great Photos!
Thanks! Definitely going to check it out. I’ve also used Picasa for this kind of work and it also does a great job.
Thanks for taking the time to write this. As another person commented, this technique should be needed less frequently as new models of DSLR’s have anti-dust systems. Also, regular sensor cleaning will help reduce dust and prevention is always better than cure.
[...] Cleaning dust on photos: or “In Gimp We Trust!” | Eugeni's blog "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)" (tags: gimp photo) Leave a Comment [...]
There’s a script for linux/gimp users called dustcleaner, unfortunately no Windows binary. Another great way to remove dust blobs is built in the Gimp, the healing brush. It works much better and faster than the clone brush, once you understand what it does. It copies the texture from a selected spot to the spot you want to heal and copies colour from near the blob.
Best way to prevent sensor dust: -Always keep your camera body pointing down when exchanging lenses -on Ebay you can buy special sticky stickers to stick inside your lens caps. You’ll be surprised how much dust these collect.