Closed-Form Matting

Python implementation of image matting method proposed in A. Levin D. Lischinski and Y. Weiss. A Closed Form Solution to Natural Image Matting. IEEE Conf. on Computer Vision and Pattern Recognition (CVPR), June 2006, New York

The repository also contains implementation of background/foreground reconstruction method proposed in Levin, Anat, Dani Lischinski, and Yair Weiss. "A closed-form solution to natural image matting." IEEE Transactions on Pattern Analysis and Machine Intelligence 30.2 (2008): 228-242.

Requirements

python 3.5+ (Though it should run on 2.7)
scipy
numpy
opencv-python

Usage

Closed-Form matting

CLI inerface:

# Scribbles input
./closed_form_matting.py input_image.png -s scribbles_image.png  -o output_alpha.png

# Trimap input
./closed_form_matting.py input_image.png -t scribbles_image.png  -o output_alpha.png

# Add flag --solve-fg to compute foreground color and output RGBA image instead
# of alpha.

Python interface:

import closed_form_matting
...
# For scribles input
alpha = closed_form_matting.closed_form_matting_with_scribbles(image, scribbles)

# For trimap input
alpha = closed_form_matting.closed_form_matting_with_trimap(image, trimap)

# For prior with confidence
alpha = closed_form_matting.closed_form_matting_with_prior(
    image, prior, prior_confidence, optional_const_mask)

# To get Matting Laplacian for image
laplacian = compute_laplacian(image, optional_const_mask)

Foreground and Background Reconstruction

CLI interface (requires opencv-python):

./solve_foreground_background.py image.png alpha.png foreground.png background.png

Python interface:

from solve_foreground_background import solve_foreground_background
...
foreground, background = solve_foreground_background(image, alpha)

Results

Original image	Scribbled image	Output alpha	Output foreground

More Information

The computation is generally faster than the matlab version thanks to more vectorization. Note. The computed laplacian is slightly different due to array ordering in numpy being different than in matlab. To get same laplacian as in matlab change,

indsM = np.arange(h*w).reshape((h, w)) ravelImg = img.reshape(h*w, d) to indsM = np.arange(h*w).reshape((h, w), order='F') ravelImg = img.reshape(h*w, d, , order='F'). Again note that this will result in incorrect alpha if the D_s, b_s orderings are not also changed to order='F'F.

For more information see the original paper http://www.wisdom.weizmann.ac.il/~levina/papers/Matting-Levin-Lischinski-Weiss-CVPR06.pdf The original matlab code is here http://www.wisdom.weizmann.ac.il/~levina/matting.tar.gz

Disclaimer

The code is free for academic/research purpose. Use at your own risk and we are not responsible for any loss resulting from this code. Feel free to submit pull request for bug fixes.

zhf459/closed-form-matting