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It depends on your definition of "lensless". You know those kids' books that have the bumpy plastic coating and when you turn the book one way you see one imag
by crusso 9y ago
It depends on your definition of "lensless".
You know those kids' books that have the bumpy plastic coating and when you turn the book one way you see one image - look at it from a different angle and you see another image?
This is the same concept. They have a bumpy plastic coating that sends the incoming light in different directions. They do some processing on standard images to determine how the scattering works and then use that scattering pattern to reconstruct new images.
I would view the bumpy coating as a myriad of lenses that change the character of the incoming light.
We have one of those windows in our bathroom with the glass that is warped so that it breaks up the light so much that it gives you privacy. I've often thought that it would be a fun project to create a camera system that you could calibrate to decrypt that scattered image by placing a known image behind the window and pre-determining how the light waves are refracted. It's cool to see that someone implemented something similar.
- saycheese 9y agoOn the same note, depends on how you define “scanning” sense they’re clearly scanning. You can do the same thing they’re doing with a bunch of pinhole, video feed with variation in the lighting, etc.
- nwatson 9y agoI think "scanning" would imply compositing info gathered at different instances of time to reconstruct 3-D models ... e.g., LIDAR captures a point cloud with points measured at different times and tries to reconstruct objects from that point cloud. Perhaps the time it takes LIDAR to gather the whole point cloud is small, but objects will drift during that time and the reconstruction algorithm might need to account for this. On the other hand, the article's method captures all info in one instantaneous image and reconstructs based on the known, recorded, bias of the irregular lens and the implied 3-D locations of objects.
- leeoniya 9y ago> You know those kids' books that have the bumpy plastic coating and when you turn the book one way you see one image - look at it from a different angle and you see another image? fyi: https://en.m.wikipedia.org/wiki/Lenticular_lens https://en.m.wikipedia.org/wiki/Lenticular_lens
- iaw 9y agoI don't think you know what the word 'lens' means[0]. It has a pretty solid definition, and the objects used in the paper do not meet it. To be a lens the object has to focus or disperse light via refraction, the objects used in the paper and then referenced in the article diffuse[1] light. Even relaxing the definition of lens to be an object designed to have particular optical properties, the diffusion filters referenced in the article weren't designed but chosen arbitrarily (they use the laminate from an ID badge at one point). That's the bulk of the reason this is valuable is because it eliminates one of the most expensive components required to accomplish the same result (the micro-array lens they reference in the article). Now, the lenticular lens you referenced is a lens because of how it operates, but the referenced in the article technique definitively does not require a lens because lenses aren't diffusers. Does that make sense? [0] https://en.wikipedia.org/wiki/Lens_(optics) https://en.wikipedia.org/wiki/Lens_(optics) [1] https://en.wikipedia.org/wiki/Diffuser_(optics) https://en.wikipedia.org/wiki/Diffuser_(optics)
- crusso 9y agoI don't think you know what the word 'lens' means I'm not really interested in having a semantic argument about the meaning of lens, but what the heck... To be a lens the object has to focus or disperse light via refraction, the objects used in the paper and then referenced in the article diffuse[1] light What do you think the "bumpy piece of plastic" in the article does, if not focus and disperse light using refraction? There's no separate optical effect called "diffusion" that isn't based upon dispersion. As a matter of fact, often a diffuser is referred to as a "diffuser lens": https://www.ylighting.com/element-lighting-accessory-lenses.html https://www.ylighting.com/element-lighting-accessory-lenses.... the diffusion filters referenced in the article weren't designed but chosen arbitrarily Nothing I said indicated that the specific bumpy plastic patterns needed to be designed. See my related thoughts on decoding images seen through privacy glass. It's the same concept, except they use the refracted images to specifically select for multiple incoming light angles to create 3D images (when they're doing the 3D image part). I actually understand how they did what they did fairly well. I read the first couple of lines in the article and knew that they had implemented the same concept that I had thought about years ago. Now, the lenticular lens you referenced is a lens because of how it operates, but the referenced in the article technique definitively does not require a lens because lenses aren't diffusers. Does that make sense? I think maybe you're coming at this subject from photography terminology? Perhaps that's why you think there's some kind of distinction between a "lens" and a "diffuser". I'm coming at it from a physics perspective where these are really the same thing.
- logfromblammo 9y agoFrosted glass can often be restored to transparency by putting a strip of clear tape over the rough side. And I agree that your privacy-glass camera would be a fun project. The kicker is that it may even be able to reconstruct portions of the 3-d scene behind the window that would not have been visible through a clear window. I recall seeing a project to create a camera that can see around corners by analyzing the diffuse reflections on surfaces visible to the camera. It would be almost the same principle.
- vorotato 9y agoActually that bumpy coating was the prior state of the art, this is instead a diffusing filter like scotch tape, and specifically works by not focusing light.
- deleted 9y ago[deleted]