readme

图象前景提取程序

This package contains an implementation of the matting algorithm described in
the CVPR2006 paper:
"A Closed Form Solution to Natural Image Matting" 
by A.Levin D.Lischinski and Y.Weiss

Usage of this code is free for research purposes only. 
Please refer to the above publication if you use this code. 

Copyrights: The Hebrew University of Jerusalem, 2006.
All rights reserved.

Written by Anat Levin. 
Please address comments/suggestions/bugs to [e-mail]
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To run the matting algorithm, use the runMatting script. 
The scripts runMatting_*.m are example scripts, calling runMatting on the 
images used in the paper.
simple examples to start with, could be:
runMatting_Kid2.m, runMatting_Hair.m, runMatting_Dandelion.m 

The runMatting script uses the arguments described below.


Input arguments:

img_name - input image file

scribs_img_name - input image with black&white scribbles 
                  Note that since the code uses a simple diff to find the 
                  scribbled pixels, you should not place scribbles with fuzzy 
                  boundaries. Photoshop users- use pencil tool, hard brushes.  


Output arguments:

alpha, F,B - representing the alpha matte and the estimation of foreground 
             and background colors.



Additional (optional) input arguments: (if you don't define them a default 
                                        value will be used)
 
epsilon - regularization term (see eq 3 in the paper)
          The default value is epsilon=0.1^7. For jpeg or noisy images use
          epsilon=0.1^5.

win_size - size of the windows in which the linear model is used 
           (default is 3x3 windows) 


For running matting using multi resolutions:

levels_num - number of levels to use

active_levels_num - use active_levels_num<=levels_num. 
                    If active_levels_num<levels_num then in the finer 
                    resolutions alpha is not computed explicitly. Instead the 
                    linear coefficients of the coarser resolution are 
                    interpolated.

thr_alpha - threshold on alpha, determines which pixels will be considered as 
            constraints when passing from a coarser level to a finer one.

Note: when multi-resolution is used, verify that the scribbles are wide enough.
Thin scribbles might disappear in the coarser resolutions. 

The examples in this package were tested on a 2GB RAM machine. 
Some of them might run out of memory on machines with less RAM.