# Is it possible to 'reconstruct" (?) an entire photo from a piece of the negative? **URL:** \ **Category:** Factual Questions\ **Created:** [February 18, 2023, 6:50am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972 "2023-02-18T06:50:21Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Amikejo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/amikejo/32/13637_2.png) [@Amikejo](https://boards.straightdope.com/u/Amikejo)\ **Post date:** [February 18, 2023, 6:50am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/1 "2023-02-18T06:50:21Z")
I don’t know how ask the question better because I know nothing about photography and I only heard a vague description of this. The only other thing I can remember is that it involves lasers. So is possible to recreate a whole photo by using only a piece of the negative? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [February 18, 2023, 7:20am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/2 "2023-02-18T07:20:42Z")
You are thinking of holograms. > **[Why does a hologram, when broken, behave like the full complete original...](https://www.quora.com/Why-does-a-hologram-when-broken-behave-like-the-full-complete-original-picture-only-smaller)** > > Answer (1 of 4): Interesting challenge! This is one of the situations where a bit of math explains it much better, but since five years old don't know Fourier transforms, I will try to go around it. > > One way to describe an object is by enumerating... ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 18, 2023, 11:48am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/3 "2023-02-18T11:48:14Z")
To finish answering the other side of that question … For an ordinary film photograph taken under ordinary light by an ordinary camera … No, it is not possible to reconstruct any part of the negative that is missing. Each little spot on the surviving negative of whatever color and transparency only contains information about the corresponding spot of the scene that it represents. ---
**Author:** ![Amikejo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/amikejo/32/13637_2.png) [@Amikejo](https://boards.straightdope.com/u/Amikejo)\ **Post date:** [February 18, 2023, 12:02pm UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/4 "2023-02-18T12:02:44Z")
I see. Thanks. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 18, 2023, 2:50pm UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/5 "2023-02-18T14:50:29Z")
Further detail on how holograms work: A hologram works, roughly speaking, like a window. You look through the window, and you see what’s on the other side. But the size of the window has essentially no relation to the size of the scene you can see on the other side of the window. You can look through a window that’s only a few inches across, and see an entire landscape stretching across miles. When people say that even a small piece of a hologram contains the entire image, that’s basically the same as saying that, if you take a large picture window and paint over everything except a small clear spot, you can still see the entire scene through that small clear spot. But you won’t get as good a view of the scene through the small spot as you would through the entire large window, because you can only see it from a very limited point of view. Maybe, from that tiny spot, you can’t see the street sign across the street, because from that vantage point, there’s a tree branch covering it, but if you had the whole window, you could move over a bit to see past the tree branch. So too with holograms: A small piece of the hologram still shows the whole scene, but not as well, because some things will be obstructed. ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [February 18, 2023, 9:01pm UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/6 "2023-02-18T21:01:41Z")
A hologram captures the light wave form as it hits the photographic plate. This works because a laser is just one pure wavelength of light; the hologram photographic plates are thicker than a wavelength, so they are essentially capturing the 3D image of the reflected waves. (Technically, they are capturing the interference pattern between the reflected light and a pure “reference” beam. And to view the hologram, shine a reference beam on the photo plate and it “recreates” to reflected wavefront - much the same as a small hole turns a horizontal wave hitting it into a circular wave around the hole on the other side.) ---
**Author:** ![fordgt100](https://avatars.discourse-cdn.com/v4/letter/f/5daacb/32.png) [@fordgt100](https://boards.straightdope.com/u/fordgt100)\ **Post date:** [March 1, 2023, 4:39am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/7 "2023-03-01T04:39:45Z")
No. Think about it, how could you recreate what ain’t there? By the way, all I do regarding photography is film photography, darkroom printing, etc. Your negative is the blueprint for your print. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [March 1, 2023, 6:31am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/8 "2023-03-01T06:31:12Z")
Perhaps the high level way of thinking about the implicit question of photograph versus hologram is this. A conventional photograph is capturing a mapping from 3D space via a simple projection onto a 2D plane. The negative is a 1-1 mapping of this projection. If you cut a corner out of the negative you just have your record of that corner of the projection. A hologram is also a mapping from 3D into a 2D plane, but it isn’t a simple projection. In a useful sense the hologram is a frequency space representation of the source. If you take a corner from a hologram that corner contains _some_ frequency space information for everything in the source field. Reconstruction of the field yields a version of the entire source but with an information content limited by how big the corner is relative to the entire hologram. Everything is there. Just in very degraded resolution. So the corner of each contains the same quantity of information. But the negative corner has full information of a small part of the source, the corner of the hologram has partial information of the whole. In a very deep way there are no free lunches. ---
**Author:** ![Amikejo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/amikejo/32/13637_2.png) [@Amikejo](https://boards.straightdope.com/u/Amikejo)\ **Post date:** [March 1, 2023, 7:04am UTC](https://boards.straightdope.com/t/is-it-possible-to-reconstruct-an-entire-photo-from-a-piece-of-the-negative/979972/9 "2023-03-01T07:04:02Z")
I understand now. It must be holograms I was thinking of. Thanks for the explanation. @Francis_Vaughan