The Inverse Compositional Algorithm for Parametric Motion Estimation
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*******
SUMMARY
*******

This program implements the modified inverse compositional algorithm for
parametric motion estimation. It computes a planar transformation between two
images, including translations, similarities, affinities and homographies. It
computes large displacements through a pyramidal scheme and uses robust
functionals to deal with noise and occlusions.

Reference articles:

[1] S. Baker and I. Matthews, Lucas-kanade 20 years on: A unifying framework,
International journal of computer vision, 56 (2004), pp. 221-255.

[2] S. Baker, R. Gross, I. Matthews, and T. Ishikawa, Lucas-kanade 20 years
on: A unifying framework: Part 2, Tech. Report CMU-RI-TR-03-01, Robotics
Institute, Pittsburgh, PA, February 2003.

This program is part of an IPOL publication:
http://www.ipol.im/


******
AUTHOR
******

Thibaud Briand <[email protected]>
Laboratoire d'information Gaspard Monge (LIGM)
Ecole Nationale des Ponts et Chaussées (ENPC)

Javier Sánchez Pérez <[email protected]>
Centro de Tecnologías de la Imagen (CTIM)
Universidad de Las Palmas de Gran Canaria


*******
VERSION
*******

Version 1, released on ???


*******
LICENSE
*******

This program is free software: you can use, modify and/or redistribute it
under the terms of the simplified BSD License. You should have received a
copy of this license along this program. If not, see
<http://www.opensource.org/licenses/bsd-license.html>.

Copyright (C) 2018, Thibaud Briand <[email protected]>
Copyright (C) 2015, Javier Sánchez Pérez <[email protected]>
All rights reserved.


***********
COMPILATION
***********

Required environment: Any unix-like system with a standard compilation
environment (make and C and C++ compilers)

Required libraries: libpng, lipjpeg, libtiff

Compilation instructions: run "make" to produce an executable
"inverse_compositional_algorithm"


*****
USAGE
*****

The program reads two input images, take some parameters and produce a
parametric model. The meaning of the parameters is thoroughly discussed on the
accompanying IPOL article. Usage instructions:

  <Usage>: inverse_compositional_algorithm image1 image2 [OPTIONS]

  OPTIONS:
  --------
	 -f name         Name of the output filename that will contain the
		           computed transformation
		           Default value transform.mat
         -o N            Output transformation format: 
                           0-Parametrization
                           1-3x3 Projective matrix
                           Default value 0
	 -n N            Number of scales for the coarse-to-fine scheme
		           Default value 0
	 -z F            Zoom factor used in the coarse-to-fine scheme
		           Values must be in the range (0,1)
		           Default value 0.50
	 -e F            Threshold for the convergence criterion
		           Default value 0.0010
	 -t N            Transformation type to be computed:
		           2-translation; 3-Euclidean transform; 4-similarity
		           6-affinity; 8-homography
		           Default value 8
	 -r N            Use robust error functions:
		           0-Non robust (L2 norm); 1-truncated quadratic
		           2-Geman & McLure; 3-Lorentzian 4-Charbonnier
		           Default value 3
	 -l F            Value of the parameter for the robust error function
		           A value <=0 if it is automatically computed
		           Default value 0
	 -s N            First scale used in the pyramid
		           Default value 0
	 -c N            Use grayscale conversion (1) or not (0)
		           Default value 1
	 -d N            Distance to the boundary
		           Default value 5
	 -p N            Parameter to discards boudary pixels (1) or not (0)
		           Default value 1
	 -g N            Use gradient type:
		           0-Central differences; 1-Hypomode
		           2-Farid 3x3; 3-Farid 5x5; 4-Sigma 3; 5-Sigma 6
		           Default value 3
	 -v              Switch on verbose mode.

Execution examples:

  1.Default parameters:

   >inverse_compositional_algorithm data/homography1.png data/homography2.png

  2.Computing an affinity with the truncated quadratic and verbose mode:

   >inverse_compositional_algorithm data/homography1.png data/homography2.png
                                    -t 6 -r 1 -v

If a parameter is given an invalid value it will take a default value.


*************
LIST OF FILES
*************
bicubic_interpolation.cpp: Computes the bicubic interpolation of an image
file.cpp:   Functions for input/output
iio.c:      Functions to read and write images
inverse_compositional_algorithm.cpp: Implementation of the method
main.cpp:   Main algorithm to read the command line parameters
mask.cpp:   Function to compute the gradient of an image and apply a Gaussian
matrix.cpp: Multiplication of matrices and vectors and calculating the inverse
transformation.cpp: Compute the Jacobian and the composition of transformations
zoom.cpp:   Compute the zoom-out of an image and the zoom-in of the parameters

Complementary programs (used for the online demo only):
equalization.c: Program to equalize the constrast of two images
mt19937ar.c   : Program to generate random numbers, used in noise.cpp
noise.cpp     : Program to add Gaussian noise to the input images
output.cpp    : Program to compute some images and error metrics from the results