Mercurial > thoughts
comparison org/adelson-notes.org @ 66:eae81fa3a8e0
add camera timing idea.
| author | Robert McIntyre <rlm@mit.edu> |
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| date | Thu, 03 Oct 2013 17:42:48 -0400 |
| parents | |
| children | 036fe1b13120 |
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| 65:1c6af9dd64d5 | 66:eae81fa3a8e0 |
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| 1 #+title: Notes for "Special Topics in Computer Vision" | |
| 2 #+author: Robert McIntyre | |
| 3 #+email: rlm@mit.edu | |
| 4 #+description: | |
| 5 #+keywords: | |
| 6 #+SETUPFILE: ../../aurellem/org/setup.org | |
| 7 #+INCLUDE: ../../aurellem/org/level-0.org | |
| 8 #+babel: :mkdirp yes :noweb yes :exports both | |
| 9 | |
| 10 * Fri Sep 27 2013 | |
| 11 | |
| 12 Lambertian surfaces are a special type of Matt surface. They reflect | |
| 13 light in all directions equally. They have only one parameter, the | |
| 14 amount of energy that is absorbed/re-emitted. | |
| 15 | |
| 16 [[../images/adelson-checkerboard.jpg]] | |
| 17 #+caption: Lol checkerboard illusion. | |
| 18 | |
| 19 Look into Helmholtz' stuff, it might be interesting. It was the | |
| 20 foundation of both vision and audition research. Seems to have took | |
| 21 a sort of Baysean approach to inferring how vision/audition works. | |
| 22 | |
| 23 - Homomorphic filtering :: Oppenhiem, Schafer, Stockham, 1968. also | |
| 24 look at Stockham, 1972. | |
| 25 | |
| 26 Edwin Land was Adelson's hero back in the day. He needed to create a | |
| 27 color photo for the Polaroid camera. In order to process for | |
| 28 automatic development of film, he had to get a good approximation for | |
| 29 the illumination/reflectance decomposition that humans do, which he | |
| 30 called Retinex. | |
| 31 | |
| 32 Cornsweet square wave grating is cool. | |
| 33 | |
| 34 - Retinex :: use derivatives to find illumination. Sort of | |
| 35 implicitly deals with edges, etc. Can't deal with | |
| 36 non-lambertian objects. | |
| 37 | |
| 38 | |
| 39 Adelson introduces the problem as an "inverse" problem, where you | |
| 40 try to "undo" the 3-d projection of the world on your retina. | |
| 41 | |
| 42 On the functional view of vision : "What it takes" is to build a | |
| 43 model of the world in your head. The bare minimum to get success in | |
| 44 life is to have a model of the world. Even at the level of a single | |
| 45 cell, I think you still benefit from models. | |
| 46 | |
| 47 Spatial propagation is ABSOLUTELY required to separate embossed | |
| 48 stuff from "painted" stuff. Edges, likewise, MUST have spatial | |
| 49 context to disambiguate. The filters we use to deal with edges must | |
| 50 have larger spatial context to work, and the spatial extent of this | |
| 51 context must be the ENTIRE visual field in some cases! | |
| 52 | |
| 53 ------------------------------------------------------------ | |
| 54 | |
| 55 ** Illumination, shape, reflectance all at once | |
| 56 | |
| 57 What if we tried to infer everything together? Some images are so | |
| 58 ambiguous it requires propagation from all three qualities to | |
| 59 resolve the ambiguity. | |
| 60 | |
| 61 Brain has a competing painter, sculptor, and gaffer which each try | |
| 62 to "build" the things in the world. There is a cost to everything | |
| 63 such as paints, lights, and material, and then you try to optmize | |
| 64 some cost function using these primitives. | |
| 65 | |
| 66 | |
| 67 Horn, technical report, 1970 |