Volume deformation correction in UWA images

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Digital Nigel Veteran Member • Posts: 9,458
Volume deformation correction in UWA images
2

There has been some discussion of volume deformation correction in UWA images in the other UWA thread. There were getting mixed up and confused with the entirely different perspective (keystone) correction and lens corrections, so I thought it would be better to started a different thread looking only at volume deformation correction.

Volume deformation is inevitable in ultra wide angle shots. It's not a lens error, camera fault, or user mistake. It has the effect of fattening people at the edges of such images. This can be corrected manually, but not easily, but DxO Viewpoint provides two completely automatic ways of fixing it. Neither is perfect, and it's often worth trying both and choosing the better looking result.

Let's look at an example. First, the image with no perspective or volume deformation correction applied:

No volume correction applied. Note how people at the edges are fattened. Image uploaded full size,  8028x5304

Now let's apply Horizontal/Vertical volume deformation correction. This keeps straight lines straight, but stretches corners:

H/V correction. People at the edges no longer fattened, and straight lines kept straight, but corners are stretched; image size 7270x5304.

DxO also provides an alternative volume correction correction, called Diagonal correction:

Diagonal correction. People no longer fattened, but the image edges are cropped and straight lines are bent, giving more of a fish-eye effect. Corners not stretched. Image size 7956x5304

In both cases, people in the middle are not distorted, while the distortions of those at the edges are corrected.

Now let's look at a different (APS-C) camera and different UWA lens. As before, I've not applied any perspective correction. Again, the first image has no volume correction:

No volume correction (6013x4000)

Horizontal volume correction (5303x4000)

Diagonal volume correction (6004x4000)

.

And another set with the same lens but a different camera:

No volume correction, people fattened

HV volume correction

Diagonal volume correction (more cropping, straight lines are bent, but it does the best job with people,)

.

Note that these corrections are completely automatic: you just have to turn them on, which I do by default (in other words, HW corrections are applied as required to every image I process, with zero clicks needed). No manual tweaking is needed, though it's possible if desired. And as I mentioned upfront, this is nothing to do with adjusting perspective or lens geometry corrections.

Perhaps these corrections could be created manually in other software, image by image, but I know of no other software that does it automatically.

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IanYorke Veteran Member • Posts: 3,532
Re: Volume deformation correction in UWA images

Digital Nigel wrote:

There has been some discussion of volume deformation correction in UWA images in the other UWA thread. There were getting mixed up and confused with the entirely different perspective (keystone) correction and lens corrections, so I thought it would be better to started a different thread looking only at volume deformation correction.

Volume deformation is inevitable in ultra wide angle shots. It's not a lens error, camera fault, or user mistake. It has the effect of fattening people at the edges of such images. This can be corrected manually, but not easily, but DxO Viewpoint provides two completely automatic ways of fixing it. Neither is perfect, and it's often worth trying both and choosing the better looking result.

Let's look at an example. First, the image with no perspective or volume deformation correction applied:

No volume correction applied. Note how people at the edges are fattened. Image uploaded full size, 8028x5304

Now let's apply Horizontal/Vertical volume deformation correction. This keeps straight lines straight, but stretches corners:

H/V correction. People at the edges no longer fattened, and straight lines kept straight, but corners are stretched; image size 7270x5304.

DxO also provides an alternative volume correction correction, called Diagonal correction:

Diagonal correction. People no longer fattened, but the image edges are cropped and straight lines are bent, giving more of a fish-eye effect. Corners not stretched. Image size 7956x5304

In both cases, people in the middle are not distorted, while the distortions of those at the edges are corrected.

Now let's look at a different (APS-C) camera and different UWA lens. As before, I've not applied any perspective correction. Again, the first image has no volume correction:

No volume correction (6013x4000)

Horizontal volume correction (5303x4000)

Diagonal volume correction (6004x4000)

.

And another set with the same lens but a different camera:

No volume correction, people fattened

HV volume correction

Diagonal volume correction (more cropping, straight lines are bent, but it does the best job with people,)

.

Note that these corrections are completely automatic: you just have to turn them on, which I do by default (in other words, HW corrections are applied as required to every image I process, with zero clicks needed). No manual tweaking is needed, though it's possible if desired. And as I mentioned upfront, this is nothing to do with adjusting perspective or lens geometry corrections.

Perhaps these corrections could be created manually in other software, image by image, but I know of no other software that does it automatically.

Yes, one of DXO-Photolab's strengths is that it tries to make raw processing "simple".  This is why I always recommend it to jpg shooters who want to try raw.  I mainly use C1Pro but DXO's PRIME noise reduction and lens corrections are superior to C1Pro.

Ian

Michael W00d Contributing Member • Posts: 989
Re: Volume deformation correction in UWA images

Thanks Nigel. The results with Viewpoint are excellent, so I shall give it a go.

Michael

Sailor Blue
Sailor Blue Forum Pro • Posts: 15,010
Re: Volume deformation correction in UWA images

Until recently I haven't had a lens wide enough to show this type of distortion.  I'm still getting used to the lens so I haven't investigated doing distortion corrections.

Adobe provides free software to create a lens correction profile for your specific lens with your specific camera that can be used in Lightroom or in ACR.

Adobe - Adobe Lens Profile Creator : For Windows : Adobe Lens Profile Creator 1.0.4

Adobe - Lensprofile Creator Userguide.pdf

Have you tried this as a way of reducing or eliminating volume deformation?

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OP Digital Nigel Veteran Member • Posts: 9,458
Re: Volume deformation correction in UWA images

Sailor Blue wrote:

Until recently I haven't had a lens wide enough to show this type of distortion. I'm still getting used to the lens so I haven't investigated doing distortion corrections.

Adobe provides free software to create a lens correction profile for your specific lens with your specific camera that can be used in Lightroom or in ACR.

Adobe - Adobe Lens Profile Creator : For Windows : Adobe Lens Profile Creator 1.0.4

Adobe - Lensprofile Creator Userguide.pdf

Have you tried this as a way of reducing or eliminating volume deformation?

No, but volume deformation is something quite different to lens distortion, so I don't think you could get the same correction effect. Of course, I don't need to, as I have Viewpoint, which automatically does it for me with zero clicks.

I do notice the volume deformation (ie, fattened people at the edges) in most published UWA images, so it would appear that not even most professional photographers are aware of the problem, or able to fix it.

And now that high end smartphones often come with an UWA camera, a lot more people will be taking such images. Of course, it may be that those phone cameras automatically apply some form of volume deformation corrections themselves — I don't know. If not already available, it does appear that researchers are working on the problem:

https://www.androidauthority.com/ultra-wide-distortion-algorithm-google-999272/

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Ernie Misner
Ernie Misner Veteran Member • Posts: 5,398
Re: Volume deformation correction in UWA images

Thanks for this and it is educational.  You have it turned on by default, but there are two methods, right?  So which method does default activate?  Thanks.

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OP Digital Nigel Veteran Member • Posts: 9,458
Re: Volume deformation correction in UWA images
1

Ernie Misner wrote:

Thanks for this and it is educational. You have it turned on by default, but there are two methods, right? So which method does default activate? Thanks.

I've set it for horizontal distortion to be applied by default, as that keeps straight lines straight and doesn't crop. That's good for shots that include buildings, so it seems like the better general-purpose solution.

It only takes one click to switch to diagonal correction, which does a better job with people near the corners, but at the expense of bending straight lines and cropping the (now curved) edges.  You can also experiment with the extent of the correction by moving the slider.

Note that either of these corrections changes the aspect ratio of the shot, making it narrower. You may then choose to crop it to the original aspect ratio, which takes out some of the sky and foreground, which is actually a very good idea if you've taken a UWA shot with the camera held horizontal, as you've probably picked up more foreground than you want in the composition.

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Pieloe
Pieloe Forum Member • Posts: 72
Re: Volume deformation correction in UWA images
3

Very clear Nigel.

I wrote a complete tutorial to ViewPoint

http://tuto.dxo.free.fr/EN/ViewPoint/ViewPoint.html

Pascal

OP Digital Nigel Veteran Member • Posts: 9,458
Re: Volume deformation correction in UWA images
1

Pieloe wrote:

Very clear Nigel.

I wrote a complete tutorial to ViewPoint

http://tuto.dxo.free.fr/EN/ViewPoint/ViewPoint.html

Thanks, Pascal. In particular, in the context of this thread, your section on volume distortion correction is well worth a read:

http://tuto.dxo.free.fr/EN/ViewPoint/ViewPoint.html#10_Correction_Deformation_de_Volume

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tokumeino Senior Member • Posts: 2,757
Re: Volume deformation correction in UWA images

IanYorke wrote:

Yes, one of DXO-Photolab's strengths is that it tries to make raw processing "simple". This is why I always recommend it to jpg shooters who want to try raw. I mainly use C1Pro but DXO's PRIME noise reduction and lens corrections are superior to C1Pro.

I agree.

As a former DXO user (former because I use Fuji X, now), I think that DXO's NR is very overrated and that what really makes DXO stand over the crowd is Viewpoint. When compared to Adobe which doesn't even let you disable a built-in lens profile, it's miles ahead.

I wish that one day, DXO supports XTrans.

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Ernie Misner
Ernie Misner Veteran Member • Posts: 5,398
Re: Volume deformation correction in UWA images

Digital Nigel wrote:

Ernie Misner wrote:

Thanks for this and it is educational. You have it turned on by default, but there are two methods, right? So which method does default activate? Thanks.

I've set it for horizontal distortion to be applied by default, as that keeps straight lines straight and doesn't crop. That's good for shots that include buildings, so it seems like the better general-purpose solution.

It only takes one click to switch to diagonal correction, which does a better job with people near the corners, but at the expense of bending straight lines and cropping the (now curved) edges. You can also experiment with the extent of the correction by moving the slider.

Note that either of these corrections changes the aspect ratio of the shot, making it narrower. You may then choose to crop it to the original aspect ratio, which takes out some of the sky and foreground, which is actually a very good idea if you've taken a UWA shot with the camera held horizontal, as you've probably picked up more foreground than you want in the composition.

Great explanation, thank you.

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cwinte Regular Member • Posts: 387
Re: Volume deformation correction in UWA images

Useful info, thanks. I also experimented with open source defishing and geometry tools and there are many ways to bend images.

But something that integrates a few simple basic options that suit many common situations is great.

For the OP the issue is to be aware of this stuff! There are choices to be made and the £d volume cannot be made flat without some consequences. Just like map making there are many projections available and they all have the good and bad points - an informed choice is needed.

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