optFlowLk

PURPOSE ^

Calculate optical flow using Lucas & Kanade. Fast, parallel code.

SYNOPSIS ^

function [Vx,Vy,reliab]=optFlowLk( I1, I2, winN,winSig, sigma, thr, show )

DESCRIPTION ^

 Calculate optical flow using Lucas & Kanade.  Fast, parallel code.

 Note that the window of integration can either be a hard square window of
 radius winN or it can be a soft 'gaussian' window with sigma winSig.
 In general the soft window should be more accurate.

 USAGE
  [Vx,Vy,reliab]=optFlowLk( I1, I2, winN, ...
    [winSig], [sigma], [thr], [show] )

 INPUTS
  I1, I2  - input images to calculate flow between
  winN    - window radius for hard window (=[] if winSig provided)
  winSig  - [] sigma for soft 'gauss' window (=[] if winN provided)
  sigma   - [1] amount to smooth by (may be 0)
  thr     - [3e-6] ABSOLUTE reliability threshold (min eigenvalue)
  show    - [0] figure to use for display (no display if == 0)

 OUTPUTS
  Vx, Vy  - x,y components of flow  [Vx>0->right, Vy>0->down]
  reliab  - reliability of flow in given window (cornerness of window)

 EXAMPLE
  % create square + translated square (B) + rotated square (C)
  A=zeros(50,50); A(16:35,16:35)=1;
  B=zeros(50,50); B(17:36,17:36)=1;
  C=imrotate(A,5,'bil','crop');
  optFlowLk( A, B, [], 2, 2, 3e-6, 1 );
  optFlowLk( A, C, [], 2, 2, 3e-6, 2 );
  % compare on stored real images (of mice)
  load optFlowData;
  [Vx,Vy,reliab] = optFlowLk( I5A, I5B, [], 4, 1.2, 3e-6, 1 );
  [Vx,Vy,reliab] = optFlowCorr( I5A, I5B, 3, 5, 1.2, .01, 2 );
  [Vx,Vy] = optFlowHorn( I5A, I5B, 2, 3 );

 See also OPTFLOWHORN, OPTFLOWCORR

 Piotr's Image&Video Toolbox      Version 2.0
 Copyright 2008 Piotr Dollar.  [pdollar-at-caltech.edu]
 Please email me if you find bugs, or have suggestions or questions!
 Licensed under the Lesser GPL [see external/lgpl.txt]

CROSS-REFERENCE INFORMATION ^

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