
Distortion-Free Wide-Angle Portraits on Camera Phones [video] - Ultramanoid
https://people.csail.mit.edu/yichangshih/wide_angle_portrait/#supp
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bitL
I always wondered why Zorin's original work [1] didn't make it to photography
nor 3D rendering/gaming; we basically had 2 decades of ugly perspective
distortions everybody got used to.

[1]
[http://graphics.stanford.edu/~dzorin/perception/sig95/index....](http://graphics.stanford.edu/~dzorin/perception/sig95/index.html)

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dTal
I can't quite see why this is a hard problem. Surely simply converting to a
spherical projection would do the job?

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Luc
But then straight lines become curves. This maintains straight lines.

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diydsp
I would have liked to see the results compared to ground truth. ie a picture
of the person taken from the center the lense.

And i would have like to see more false-positive rejection. e.g. stuff that
gets detected as a face but isn't- at the edges of photos, but really that
relies on the robustness of the face detect heuristic, so it's a short and
sweet heuristic that will make people look more normal at the edges of photos.

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bufferoverflow
I think some of their examples are either fake or not shown in full.

[https://i.imgur.com/eRP0fZc.jpg](https://i.imgur.com/eRP0fZc.jpg)

Look at the top-right corner.

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yorwba
The examples are not shown in full, because they also correct for
nonlinearities in the lens projection.
[https://people.csail.mit.edu/yichangshih/wide_angle_portrait...](https://people.csail.mit.edu/yichangshih/wide_angle_portrait/shih_sig19_supp.pdf)

The image on the left is a rectangular crop of the image after lens
correction, the one on the right combines lens correction and their warping
method. That combination allows them to pull in a few pixels that would've
been outside the rectangular region otherwise.

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jimbo1qaz
Going into this paper, i expected they would be correcting for barrel
distortion. I was disappointed to read that they instead:

>we formulate an optimization problem to create a content-aware warping mesh
which locally adapts to the stereographic projection on facial regions, and
seamlessly evolves to the perspective projection over the background.

Reminds me of this person who wrote a youtube tutorial with the factually
incorrect title "Manually correct perspective in Photoshop". He did not
correct the (already correct) perspective, but rather selectively distorted
parts of scenery photographs so bridges looked "vertical". In fact, he was
making those parts of the image no longer conform to the mathematical photo
projection. Instead of picking a better-suited image projection, that video
and this paper selectively fudge parts of the image to use a different
projection.

[https://youtu.be/BocAGkS8yRQ](https://youtu.be/BocAGkS8yRQ)

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antpls
Wow, Let's hope it will be included in the next release of Camera apps of
major phone OSes

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Ultramanoid
Given that the authors are all from Google, I guess we can expect this to be
working on the coming Pixel 4 at the very least.

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makr
This is actually already working on my Pixel 3 right now.

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nitrogen
Samsung's camera app as well on the newer Galaxy phones

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app4soft
What about testing it for aerial imagery?

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ris
It works by detecting faces and using a different projection for them. How
exactly would this be useful?

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randyrand
what projection do our eyes use?

