iPhone 13 wide angle files

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iPhone 13 wide angle files

Postby patrick » Thu Mar 10, 2022 7:48 pm

Hi,

I'm having issues with SNS-HDR Pro and iPhone 13 Pro wide angle images.

The attached image shows HDS-SNS output at the top with a photoshop derived HDR image below (from 7 exposures).

As you can see the images is distorted by HDR-SNS with severe curvature at the edges..

Many thanks,

Patrick

[attachment=0]HDR.jpg[/attachment]
Attachments
HDR.jpg
HDR.jpg (1.78 MiB) Viewed 1092 times
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Re: iPhone 13 wide angle files

Postby mak_kawa » Sun Mar 13, 2022 12:17 am

SNS-HDR has no lens correction functionality. So, it is reasonable if you input your photo to SNS-HDR *before* some distortion corrections applied. It is not a bug.

Generally, the RAW editing software as Photoshop (Camera RAW) applies lens correction as chromatic aberration and distortion based on embedded correction parameters within the RAW file itself. But SNS-HDR doesn't.
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Re: iPhone 13 wide angle files

Postby patrick » Mon Mar 14, 2022 2:53 pm

Hi,

Thank you for your reply.

If I open the DNG files in Photoshop and save them as JPG then the final image in SNS-HDR is undistorted.

If I understand correctly then the problem is with the RAW converter?

Does this mean LibRaw needs to be updated ?

Kind regards,

Patrick
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Re: iPhone 13 wide angle files

Postby patrick » Mon Mar 14, 2022 5:16 pm

7 identical DNG files taken using iPhone 13 Pro wide angle lens and the ProCamera app.

GIF below showing the distortion difference between the Photoshop processed image and the SNS-HDR image.

This is only happening with the wide angle lens and RAW format, the other two lens's are processed identical in both software.

HDR.gif
HDR.gif (428.79 KiB) Viewed 1038 times
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Re: iPhone 13 wide angle files

Postby mak_kawa » Mon Mar 14, 2022 11:11 pm

As far as I know, it is not LibRaw matter. LibRaw just extracts demosaiced pixel data, metadata and preview thumbnail image from RAW.
https://www.libraw.org/about

The lens corrections are Raw converter's job. Camera RAW, CaptureOne, DxO PhotoLab... etc. do that, but SNS-HDR doesn't, as I already said.
The reason why this issue happens in only wide lens is that normal and tele lenses have almost no distortion originally.

Your issue is the same with my MFT camera, Panasonic G-85 and wide lens. So, my workflow/workaround is... First, process the RAW with SNS-HDR to TIFF file. And second, correct its chromatic aberration and distortion using Lightroom. Maybe there is some IQ degradation, but no choice.
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Re: iPhone 13 wide angle files

Postby patrick » Mon Mar 14, 2022 11:46 pm

Hi mak_kawa,

Thank your for your reply.

I understand what you are saying but don't understand your suggested workflow! Or at least I understand it as much as the suggested process is not to ask SNS-HDR to process RAW files?

If I pre-process the DNG files to TIFF or JPG the SNS-HDR output is an image without edge distortion. Processing DGN files directly in SNS-HDR results in a file that no amount of lens correction/chromatic aberration can fix. Geometrically it is completely screwed.

Logically the problem is with the RAW converter? Indeed, throwing the same DGN files at Aurora HDR results in the same problem. But not Photoshop.

Where is the "Raw converter" in the SNS-HDR process?

SNS-HDR is not "passive" in this process - the resulting file is geometrically distorted compared to the original DGN files. If LibRaw just extracts data then where in the SNS process is the geometry getting screwed?

Patrick
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Re: iPhone 13 wide angle files

Postby mak_kawa » Tue Mar 15, 2022 8:38 am

I didn't suggest the workflow to you. That is *my* workflow.

> (Your question:) Where is the "Raw converter" in the SNS-HDR process?

In the SNS-HDR process, there is only LibRaw *without* lens correction capability.

And, you also said "the resulting file is geometrically distorted compared to the original DGN files". I think the original DNG data has lens distortion optically induced, and there are only parameters for RAW converter (e.g. Camera RAW) to correct them. So, when you see the photo image as a result of RAW conversion by Photoshop, there is no lens distortion, because it was already corrected by internal functionality of the Camera RAW.

Ideally, it is the best that Sebastian implemented "built-in" lens correction functionality to SNS-HDR. Some time ago, I have already proposed such implementation. But is seems to difficult to achieve. So, I am doing "my workflow" just as a workaround.
Possibly, I must move from SNS-HDR to another HDR software, but I am not sure what is the best.
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