Despite the fact that Fuji’s X-Trans cameras have been out for several years now, and despite the fact that the issues with Lightroom are well known, there is still a surprising amount of misinformation being spread about this. What’s worse is that some of it comes from what you would think would be reliable sources. One of the most confusing issues surrounds what people call “worm artefacts”. Here is my attempt to set the record straight.

Before I get into discussing the “worm artefacts”, there are a few other things I want to talk about. The reason I’m writing this is that a short while ago my work on the issue of X-Trans processing in Lightroom was referred to in the context of larger discussions that seemed to imply that there’s actually no issue with Lightroom and X-Trans and that the issue is actually with the user just using it wrong (this has since been corrected). In case there's any confusion, I want to make it clear that I don't agree with that sentiment, nor would I ever blame the user for what Adobe themselves admitted is an issue with Lightroom and camera raw's processing. It reminds me of Apple’s infamous “you’re holding it wrong” excuse. Unfortunately, in my opinion, it’s this kind of thing that’s at least partially responsible for Lightroom’s conversions never getting fixed.

Secondly, it’s not “all about the sharpening”. The issue with Lightroom is due to the way Lightroom demosaics the files. This has a knock on effect down the processing chain. It’s made substantially worse by Lightroom’s default sharpening, but the sharpening isn’t the root cause of the problem. Conversely, you can reduce the effect of the demosaicing issues by using certain sharpening settings, but again, this isn’t getting rid of the problem, it’s just minimising it. The results are probably good enough for most people, but that’s not the same thing as there not being a problem in the first place. In fact, in some cases, Lightroom’s conversions are probably fine out of the box, so long as you don’t look too closely.

This is scaled to fit the web page - so click to view properly - Lightroom Default Sharpening 1:1 Crop - Smeared/Watercolour detail on the trunk - edge issues on the leaves. Click to view at actual resolution.

I keep getting questions from people about why I use X-Transformer with the sharpening turned off. This is because I only want to use it to demosaic the files. Once you do, the issues with Lightroom go away, and you can use it normally, without any special sharpening settings. Someone got a bit irate with me recently over this subject, as they couldn’t understand why I was doing it this way, because they’d read that it was all about the sharpening, and the only issue with Lightroom was the sharpening, therefore, that’s the only reason to use X-Transformer. It’s this kind of misinformation that is causing these problems.

This is scaled to fit the web page - so click to view properly. Same image as above with X-Transformer - better definition on the tree trunk - smearing greatly reduced. Only differnece is the demosiacing.

The issues with Lightroom conversions are manifest in several ways. Most notably, it leads to a smeary watercolour effect on fine detail, and it also leads to false detail in complex patterns. I’ve covered this multiple times in the past so I won’t go over it again. The “worm artefacts” are another side-effect, but they are not directly caused by the Lightroom’s X-Trans conversions. They are made worse by it, but that’s not the root cause.

These worm artefacts that everyone talks about, ARE actually caused by Lightroom’s sharpening, and you can see them on any file from any camera. If you turn the sharpening right up, you will encounter them. Normally though, you will need to have the sharpening amount turned up full, or nearly full to see the effect. This is not a setting you would normally ever have to use unless you’re shot was out of focus. Whatever Adobe is doing internally in Lightroom with X-Trans conversions means that these artefacts appear at a much lower value than they normally would. Even in ranges between 30 - 50 you can start to see them. This is where the problem arises. You can minimise this by tweaking the settings, or use a different sharpening method by using something like photoshop. In all of my books and articles on this, I never talked about these worm artefacts, as they’re not really part of the root issue.

1:1 Crop from a Nikon D700 With Sharpening turned up full - click to view at correct resolution.

I realise that this has turned into kind of a rant, but I can't believe that after several years this hasn't been resolved. On Adobe’s forums any discussion of this is buried under an avalanche of “you’re just using it wrong” responses, so it’s no wonder Adobe doesn’t really care about this issue. This is why brand fanaticism doesn’t help anyone, and actually probably puts people off the brand in the long run. You can like a brand and still point out problems with it. That I even have to write this is kind of ridiculous, as it's just a camera at the end of the day.

The thing is that for many users Lightroom’s conversions are good enough, and I have no problem with that. In all my writing on this subject, I've always tried to point out that what I was offering was just a suggestion, and if you're happy with it as it is, then stick with that. If it's good enough for what you do, that's great. However, and this may seem like a semantic difference, but “good enough” is not the same as being correct. There are problems with the basic raw conversion of X-Trans files in Lightroom, and even if you hide them with selective processing, and even if they don’t affect you personally, that’s not the same as them not being there at all. I get that for many users it doesn't matter, and personally, I regularly use Lightroom default conversion because it is good enough. But I still know it’s wrong. It’s not a case that “you just have to deal with it differently”. You do have to deal with it differently, but this is because it’s not right, to begin with, not because you the user is doing anything wrong or it’s just different.

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