[Computer Vision 3] The Plenoptic Function and the Elements of Early Vision

The Plenoptic Function

The image information available from a single viewing position, is defined by the pencil of light rays passing through the pupil.

The plenoptic function describes the information available to an observer at any point in space and time. (connection between objects and eyes)

P(θ, φ, λ, t, Vx, Vy, Vz), or P(x, y, λ, t, Vx, Vy, Vz): P(θ, φ): spherical coordinate, P(x, y): spatal coordinate, P(λ): wavelength (color information), P(t): movie, time dimension, P(Vx, Vy, Vz): observable light intensity at every viewing position.

The Plenoptic Structure

(x, y): information about instantaneous form;

(x, λ): information about color variation along x-axis;

(x, Vx/Vy/Vz): information as eye position shift from left to right (up and down/ forward and backward).

Elemental Measurements in Early Vision/ Extracting Plenoptic Structure

Task 1: Deliver a small set of useful measurements of each observable location

Task 2: Measure local changes along various directions within plenoptic function (compute low order derivatives/ local average derivatives)