Hi, I am a novice photographer transitioning from Lightroom to RawTherapee and F/OSS tools. I was wondering, are there any GIMP analogues of Lightroom’s “Visualize Spots” feature for dust removal? For reference, it is described under “Cleaning up a photo with the Visualize Spots feature” on this Adobe help page: https://helpx.adobe.com/lightroom/help/enhanced-spot-removal.html
It looks likes I just need some edge-detection in GIMP and then I can apply spot healing to remove dust spots. What is the best way to do this?
Thanks for the link. It appears the method described there involves using the alpha/infrared channel of an image to detect dust. Unfortunately it seems that RawTherapee (which I am trying to learn to use) does not permit exporting images with that channel. So I am not sure that is a viable solution.
The alpha channel results in an additional scan with infrared illumination, which is supported by many film scanners. However, if you do not have this information, there are other possibilities to reduce dust spots, e.g. the despeckle filter from the G’MIC gimp plugin. But you asked for something else …
A solution for what you require could be the “edges” filter from the G’MIC gimp plugin.
Thanks for the suggestion. I came across the despeckle filter while Googling, however the documentation states: “You should select isolated defects before applying this filter, in order to avoid unwanted changes in other areas of your image.” So I am still left with the problem of isolating the defects somehow. I would also like to be able to do this removal “by hand” for maximal control over the results.
I will look into the “edges” filter. That may be the ticket for replicating Lightroom’s tool.
May I ask what source material you have and where the dust originates from? If it’s from film scans, I would really recommend to use an infrared capable scanner, this works like a miracle (at least for colour film, not for most b/w unfortunately).
Manual correction is what works best for me if I do not have an infrared layer, e.g. from image scans. However, for an automatic tool, the despecle filter is quite good, at least as far as I remember.
The dust is sensor dust that appears while shooting at narrow apertures on an entry-level DSLR.
I agree that manual correction is best in this case, and my question is really how best to go about that correction. I guess you use the “edges” filter?
If you’re shooting many shots at the same settings, as is the case when shooting panoramas or focus stacks, then using a flat-field can remove the dust with no effort.
No, in the case of sensor dust I just correct what I can see in the picture directly with the healing brush and do not use additional aids, everything I cannot spot by looking at it I do not care about. But I never had much dust issues on my cameras, but I have to admit that I tend to shoot wide open, especially since during recent years my (growing) family made me photograph more and more people and less landscapes.
Thank you, Morgan. The flat-field technique is quite interesting. Extra effort, but perhaps more precise pictures as a reward.
I’m still open to suggestions for manual correction, however, given that I do not (yet) have a flat field filter and would like to retain manual control over my processing.
The best I can think of is some negative filter and then the edges filter recommended above. Any other suggestions are appreciated.
The sensor I am much more scared of doing, given the potential for screw-ups. Perhaps this an unfounded fear, but if the dust ever really bothered me, I’d bring it to a licensed shop to be cleaned. Luckily things are not bad at all right now.
(But I would like to focus on the topic of dust detection and manual removal in post, not my camera maintenance failings )
Reading up a bit more, I am now curious if the LR “visualize spots” feature could be imitated or improved using the GIMP wavelet features. It seems they are quite useful for selective sharpening of edges, so I imagine they would also be useful here.
edit: Indeed, it seems GIMP’s wavelet decompose is essentially a better version of that LR feature.
@ nik: I was a little concerned as well, thus I took my camera to a center to get it “professionally” cleaned. They did it, although at the time I remember it didn’t seem to me they were taking particular care while doing it. The annoying part was when I later tried the camera and the spots were still there!
I finally decided to buy this:
I tried it, taking just some simple care, and the spots were gone!
Now I feel I don’t need to rely on any “services” to do something I can do by myself whenever I need it
The only thing to check is the right size for the cleaning swab, but usually the description is pretty accurate and, in case, just read what other buyers say about the product.
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