Volume deformation correction in UWA images

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Digital Nigel Veteran Member • Posts: 9,251
Volume deformation correction in UWA images
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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,)

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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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