When you take a digital photo, the camera you use receives light through its lens, but the light information it gets can be slightly distorted. Because of this, cameras often use lens correction to create JPEGs from the original light information, or when converting RAW files into JPEGs.
If you shoot RAW files, many apps that process these files can also apply lens correction, using metadata stored with the files, to create better images. In some cases, this can even be using a huge database of information about lenses and cameras.
It’s interesting to know that Apple’s Photos app also applies lens correction, yet doesn’t tell you anything about it. This lens correction is not only applied in the Photos app, but also within macOS; if you have a RAW file and view it using Quick Look (select the file and press the space bar), lens correction is applied.
I haven’t been able to find a database of which lenses Apple is aware of, but there is a document showing which cameras are supported for RAW files. It’s likely that Apple supports those lenses that add metadata to the RAW files, which covers most lenses people are likely to use. This said, if you’re using a non-digital lens on a camera with an adapter, you won’t get any such information; it’s possible that some third-party software may be able to apply correction for this type of lens.
So what is lens correction? Let me quote an explanation from an Adobe document about its Camera Raw app:
- Vignetting causes the edges, especially the corners, of an image to be darker than the center.
- Barrel distortion causes straight lines to appear to bow outward.
- Pincushion distortion causes straight lines to appear to bend inward.
- Chromatic aberration is caused by the failure of the lens to focus different colors to the same spot.
Here is a good explanation of these types of distortion, with a number of images showing how each one presents in photos.
Not all of these types of distortion will be obvious with all lenses; you have more pincushion distortion in a wide angle lens than a telephoto, and chromatic aberration may be very visible, or may be hard to spot, and it may depend on your subject and lighting. But have a look at an example to see how different a RAW file can look without and with lens correction.
The first screenshot below shows a file opened in Affinity Photos with the lens correction setting turned off; this makes the app display the RAW file with no alteration. The second version is from a screenshot taken when viewing the same file with Quick Look in the macOS Finder. I then scaled both screenshots to the same size.
The correction is most obvious if you look at the top corners. In correcting the distortion, the photo cuts off the corners a bit to make them straighter. You can also see an overall difference in lighting; this is a bit surprising, but both Apple Photos and Affinity Photo show the corrected photo like this. If you look very closely, you can also see the curves are a bit different, correcting the distortion.
My camera also made the same corrections to this photo in creating a JPEG. Since the information about lens distortion is included in the metadata in the RAW file, either the camera can correct when creating a JPEG or software can correct later, if you only shoot in RAW. (I generally shoot RAW + JPEG.)
Some cameras offer a setting to enable or disable lens correction, but mine don’t. And some software also has its own database of lens and camera information to correct distortion. However, “Olympus says it does not disclose its RAW file format to third-party software providers,” according to DPReview, but I see lens correction in photos shot with my Olypmus lenses in Photos and other apps. (The photo above was show with a Panasonic Lumix 20mm f 1.7 lens on an Olympus Pen-F.) It may be that software developers reverse engineer some lenses to be able to apply correction.
So why don’t camera manufacturers make better lenses? I would expect that the more expensive the lens, the less correction needed, but since this correction is possible via software, as Olympus says, quoted in this article, “[this] enables us to greatly reduce the length and volume of a lens, and gives manufacturers flexibility of small and light weight designs.”
So it’s good to know that, if you shoot RAW, Apple’s Photos applies lens correction to some or all of your images. This can save you from having to use third-party software to process your RAW files, if this distortion is problematic. It’s also interesting to know that Apple does this and doesn’t mention it; I think it would be a useful point to make to get users to stick with Apple’s simpler photo management and editing tool rather than buying a third-party app to get this feature.
(It’s interesting that DxO makes an app called DxO OpticsPro for Photos, which claims to apply optical corrections as an editing extension to Photos. However, unless it supports a much broader range of lenses and cameras than Photos itself, this optical correction is useless. It’s worth pointing out that it doesn’t support RAW files from my Fuji X100F, something that Photos does support. Go figure…)
What bothers me about this is that Apple does this without your knowledge.
It’s true that there might be cases where you might not want it applied. But if you know enough to not want it, you know how to use other apps with your RAW files.
What bothers me about this is that Apple does this without your knowledge.
It’s true that there might be cases where you might not want it applied. But if you know enough to not want it, you know how to use other apps with your RAW files.
Does this apply to the iOS Photos app as well?
No, because you can’t shoot raw with the iOS camera. I’m not sure what happens when you shoot raw with a third-party app. I’ll look into that.
Does this apply to the iOS Photos app as well?
No, because you can’t shoot raw with the iOS camera. I’m not sure what happens when you shoot raw with a third-party app. I’ll look into that.
One additional question. What if for example I use a X100F with one of the Fuji converter lens (TLC or WCL) attached? JPEGs generated by the camera would be corrected, but, what about RAF files? I suppose they will have distortion, and I’m not sure if any other photo edition app or OS would be able to discover and solve that only by reading metadata info.
Great post.
I’m not sure. If you want to send me a file show with one of the converters, I can try it out and see what happens. It all depends on whether the exif data for the converter is written in the file. Email me through my contact link at the top of the page if you want to send me a file. (Which you would have to do via Dropbox or similar, given the file size.)
One additional question. What if for example I use a X100F with one of the Fuji converter lens (TLC or WCL) attached? JPEGs generated by the camera would be corrected, but, what about RAF files? I suppose they will have distortion, and I’m not sure if any other photo edition app or OS would be able to discover and solve that only by reading metadata info.
Great post.
I’m not sure. If you want to send me a file show with one of the converters, I can try it out and see what happens. It all depends on whether the exif data for the converter is written in the file. Email me through my contact link at the top of the page if you want to send me a file. (Which you would have to do via Dropbox or similar, given the file size.)
Appreciate the post, as this is the top Google result when you search for “macOS Photos lens correction.” There’s a dearth of information about this subject, as I guess most people who deal with RAWs have an already established workflow with Lightroom or similar, and the people who care about lens correction in Photos is an even smaller subset.
From what I can gather, the RAW engine in macOS will do lens corrections for m43 cameras, as that information is a standardized part of their RAW format. Fuji also apparently burns in lens correction data into at least some of its RAWs. The RAW engine will also do lens corrections for fixed lens cameras. As for the rest, who knows? I recently picked up a Canon M100 and EF-M 22m and Photos does nothing to fix the egregious vignetting at wide apertures.
I’m pretty sure that it handles a lot of lenses, not just micro four-thirds, but I do wish there was a list of which lenses are supported.
You would think it wouldn’t be difficult for a company with Apple’s resources to maintain lens correction data for the most popular 100 lenses, or hell, the most popular 1000 lenses.
But apparently, even the Canon EF-S 18-55 kit lens isn’t corrected for, and that has to be one of the most common lenses on the planet!
https://discussions.apple.com/thread/8117790
As the applicable variable in CoreImage is called Vendor Lens Correction, perhaps Apple is only working off of what data lens manufacturers provide to them.
https://developer.apple.com/documentation/coreimage/kciinputenablevendorlenscorrectionkey
Appreciate the post, as this is the top Google result when you search for “macOS Photos lens correction.” There’s a dearth of information about this subject, as I guess most people who deal with RAWs have an already established workflow with Lightroom or similar, and the people who care about lens correction in Photos is an even smaller subset.
From what I can gather, the RAW engine in macOS will do lens corrections for m43 cameras, as that information is a standardized part of their RAW format. Fuji also apparently burns in lens correction data into at least some of its RAWs. The RAW engine will also do lens corrections for fixed lens cameras. As for the rest, who knows? I recently picked up a Canon M100 and EF-M 22m and Photos does nothing to fix the egregious vignetting at wide apertures.
I’m pretty sure that it handles a lot of lenses, not just micro four-thirds, but I do wish there was a list of which lenses are supported.
You would think it wouldn’t be difficult for a company with Apple’s resources to maintain lens correction data for the most popular 100 lenses, or hell, the most popular 1000 lenses.
But apparently, even the Canon EF-S 18-55 kit lens isn’t corrected for, and that has to be one of the most common lenses on the planet!
https://discussions.apple.com/thread/8117790
As the applicable variable in CoreImage is called Vendor Lens Correction, perhaps Apple is only working off of what data lens manufacturers provide to them.
https://developer.apple.com/documentation/coreimage/kciinputenablevendorlenscorrectionkey
„(It’s interesting that DxO makes an app called DxO OpticsPro for Photos, which claims to apply optical corrections as an editing extension to Photos. However, unless it supports a much broader range of lenses and cameras than Photos itself, this optical correction is useless. It’s worth pointing out that it doesn’t support RAW files from my Fuji X100F, something that Photos does support. Go figure…)“
Frankly, this is nonsense. Normally, lens manufacturers embed simple lens correction parameters into the lens metadata so that the lens imperfections get corrected automatically. However, these correction parameters are obviously fairly simplistic. DXO maintains a database of camera-lens combinations(!), and each combination is measured extensively and profiled. As a result, their correction profiles are far superior to the run-of-the-mill profiles embedded with lenses. Just look at any lens review and typically you see that things like distortion and vignetting are still present to some extend even in the automatically corrected photos. Not so with DXO profiles! And due to the extensive lens data they collect, they can also optimize their sharpening algorithms to each lens. The result is far more sophisticated and effective than anything else on the market.
TL;DR: The simple correction parameters provided by the lens manufacturers can correct optical imperfections fairly well, but DXO really does go the extra mile and gets the most out of every supported lens. If you want to really optimize your photos, this is the way to go. In my practical experience, the difference is striking.
Of course, DXO also has a denoising algorithm that is far superior to anything Apple has ever developed. DXO Prime is pretty much the king of denoising algorithms (even next to Adobe), so if you often shoot at high ISOs, DXO Optics is, again, an amazing extension. DXO Photolab, the standalone app, is even more powerful.
DXO Prime is also the reason why DXO doesn’t support mid- to high-end Fuji cameras. Fuji has a special sensor technology called X-Trans that doesn’t use a typical Bayer sensor to record color information. Hence, DXO would have to develop special versions of all their algorithms just for Fuji. Additionally, as far as I know Fuji doesn’t really like to cooperate in that area. Only Fuji’s cheaper cameras that use standard CMOS sensors are supported. It’s unfortunate, but it is what it is.
What’s nonsense? The fact that Photos has built in lens correction for many cameras and lenses? I find Photos’ corrections better than, say, Affinity Photos. And too bad that they would have to do a bit of work to support Fujifilm cameras; it’s their loss.
„(It’s interesting that DxO makes an app called DxO OpticsPro for Photos, which claims to apply optical corrections as an editing extension to Photos. However, unless it supports a much broader range of lenses and cameras than Photos itself, this optical correction is useless. It’s worth pointing out that it doesn’t support RAW files from my Fuji X100F, something that Photos does support. Go figure…)“
Frankly, this is nonsense. Normally, lens manufacturers embed simple lens correction parameters into the lens metadata so that the lens imperfections get corrected automatically. However, these correction parameters are obviously fairly simplistic. DXO maintains a database of camera-lens combinations(!), and each combination is measured extensively and profiled. As a result, their correction profiles are far superior to the run-of-the-mill profiles embedded with lenses. Just look at any lens review and typically you see that things like distortion and vignetting are still present to some extend even in the automatically corrected photos. Not so with DXO profiles! And due to the extensive lens data they collect, they can also optimize their sharpening algorithms to each lens. The result is far more sophisticated and effective than anything else on the market.
TL;DR: The simple correction parameters provided by the lens manufacturers can correct optical imperfections fairly well, but DXO really does go the extra mile and gets the most out of every supported lens. If you want to really optimize your photos, this is the way to go. In my practical experience, the difference is striking.
Of course, DXO also has a denoising algorithm that is far superior to anything Apple has ever developed. DXO Prime is pretty much the king of denoising algorithms (even next to Adobe), so if you often shoot at high ISOs, DXO Optics is, again, an amazing extension. DXO Photolab, the standalone app, is even more powerful.
DXO Prime is also the reason why DXO doesn’t support mid- to high-end Fuji cameras. Fuji has a special sensor technology called X-Trans that doesn’t use a typical Bayer sensor to record color information. Hence, DXO would have to develop special versions of all their algorithms just for Fuji. Additionally, as far as I know Fuji doesn’t really like to cooperate in that area. Only Fuji’s cheaper cameras that use standard CMOS sensors are supported. It’s unfortunate, but it is what it is.
What’s nonsense? The fact that Photos has built in lens correction for many cameras and lenses? I find Photos’ corrections better than, say, Affinity Photos. And too bad that they would have to do a bit of work to support Fujifilm cameras; it’s their loss.