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I know in a portrait photo we use distance between camera and the subject in such a way as to create a pleasing and hopefully natural-looking perspective. I think it's good on 1 ~ 1.5 meter to get a best portrait photo.

I'm computer engineer and have a constraint in distance. The person (subject) and camera should be at 50 cm distance.

Is there any camera or lens or any hardware filter that I can use to get a best portrait (head-shot) and prevent perspective distortion with this distance limitation?

Update 1: this is my figure captured but I think all of them is not good as well (perspective distorted):

headshot 1 headshot 2 headshot 3

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    \$\begingroup\$ What is your real problem? What are you trying to achieve? Is it some sort of computer-vision applicaiton, or photo booth, or what? In other words, why is it important that "I'm computer engineer and have a constraint in distance"? Do you want to take self-portrait using your laptop? \$\endgroup\$
    – aaaaa says reinstate Monica
    Jun 11, 2018 at 22:09
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    \$\begingroup\$ Constraint is a selfie with distance restricted to arm length 😝  No lens can correct for perspective because perspective is strictly a function of distance (as in answers by @mattdm @WayneF). But it might be doable with mutiple lenses and some 3D modeling. (Unaware of any such existing software.) \$\endgroup\$
    – xiota
    Jun 11, 2018 at 22:35
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    \$\begingroup\$ @mattdm really this is a computer capture program that need portrait picture but real and nice one and store image for rhinoplasty use. but this is a photography question not computer engineering question. Is it clear? help me to improve my question. \$\endgroup\$
    – Akj
    Jun 12, 2018 at 8:17
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    \$\begingroup\$ @Akj You need to consider your objectives. If this is a technical photograph that is being used for a technical purpose then don't worry about aesthetics and concentrate on capturing the technical information that is required for the application. If you also want to capture an aesthetically pleasing portrait of a rhinoplasty patient after the procedure, simply for marketing or patient feedback purposes, then just take a second photograph with the correct equipment for that purpose. \$\endgroup\$
    – J...
    Jun 12, 2018 at 14:19
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    \$\begingroup\$ No, as in explain why you can't have the camera farther away. \$\endgroup\$
    – JonathanReez
    Jun 12, 2018 at 20:48

2 Answers 2

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There is no hardware solution, short of some crazy* arrangement of mirrors to extend the actual optical distance. That's because perspective distortion solely related to distance, but there might be a software one, if you're able to throw a computer at the problem and able to accept some limitations.

For a computational approach, see this paper: Perspective-aware Manipulation of Portrait Photos (pdf link) — the basic idea is that you build a 3D model of the head and then use that to distort the image to match a photograph taken from a different distance. Unlike many computer graphics or computational photography papers, this one is quite readable by the layperson (e.g. me), although I admit to glossing over the actual hard part about the tensor model.

@Ian points out that there is an online demo. I ran your example through that, with this result:

animation of the magic

This solution uses a single image; I'm not sure if that's part of your constraint. Having more information for doing this kind of sorcery in software is one of the uses for multiple simultaneous cameras — think some of the new smartphones.

* If you're got a fixed location, it doesn't actually have to be so crazy. Place a large mirror pointing up at a 45° angle against the wall. Mount your camera near the ceiling. Keep the mirror clean!

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  • \$\begingroup\$ wow that paper is some cool stuff, from perspective of science. \$\endgroup\$
    – Horitsu
    Jun 12, 2018 at 4:58
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    \$\begingroup\$ Very good article! There is a link to an interactive website where you can actually try out this program with demo photos or your own: faces.cs.princeton.edu \$\endgroup\$
    – Ian
    Jun 12, 2018 at 6:39
  • \$\begingroup\$ @Horitsu I see what you did there :) \$\endgroup\$
    – mattdm
    Jun 12, 2018 at 20:32
  • \$\begingroup\$ @Ian I see your demo, you means this calculate by software or anything else? \$\endgroup\$
    – Akj
    Jun 12, 2018 at 21:41
  • \$\begingroup\$ @Akj The software is a demo by the authors of the paper. It is a software approach. \$\endgroup\$
    – mattdm
    Jun 12, 2018 at 21:51
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Classic standards have always been more like 2 meters Minimum distance for portraits. 3 meters is common in professional studios, for even better perspective. Too little distance (like 1 meter) will exaggerate and enlarge closer features like noses. This distortion will not please the subjects.

The standard notions are the 105 mm lens is good for head and shoulders portraits on full frame 35 mm film, simply because the field of view will demand and force the proper minimum distance for good perspective. And for example, a crop factor 1.5 camera would use the equivalent 105/1.5 = 70 mm equivalent focal length for proper perspective. The distance will be the same either way.

Perspective is NOT about the lens. Perspective is ONLY about the distance, i.e., where the camera stands, and the view it necessarily sees from there. If you want to improve perspective, you must change where you stand. The chosen lens might change where you must stand (for the desired field of view), but the perspective result is only about where you stand.

So stand back some. Zoom in all you want for the view you want, but stand back some if you want proper portrait perspective. Any kind of proper planning will include standing at the necessary distance. Perspective is the view seen standing at that distance.

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  • \$\begingroup\$ you means there is no way, no technique, nothing else for this close distance? am I clear? \$\endgroup\$
    – Akj
    Jun 11, 2018 at 20:38
  • \$\begingroup\$ I doubt about the meaning of "The chosen lens might change where you must stand" so you means with specific lens we can stand near? \$\endgroup\$
    – Akj
    Jun 11, 2018 at 20:41
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    \$\begingroup\$ The chosen lens can affect the size of the field of view, i.e., maybe creating a head and shoulders view. But only the distance controls the perspective, which can avoid enlargement of the near features (like the nose) caused by standing too close. \$\endgroup\$
    – WayneF
    Jun 11, 2018 at 20:45
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    \$\begingroup\$ To be fair, a "lens" could in principle create distance greater than any external dimension of the lens if it's actually a system of mirrors and lenses by bouncing light rays back and forth multiple times. \$\endgroup\$
    – R.. GitHub STOP HELPING ICE
    Jun 11, 2018 at 23:05
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    \$\begingroup\$ @R Thus, the popularity of the "bathroom mirror" selfie. \$\endgroup\$
    – Michael C
    Jun 12, 2018 at 7:57

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