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Saliency Detection via
 Divergence Analysis

Jia-Bin Huang        Narendra Ahuja

 Electrical and Computer Engineering
University of Illinois, Urbana-Champaign
Jia-Bin Huang         Narendra Ahuja
jbhuang1@illinois.edu
   n-ahuja@illinois.edu
What this talk is about?
1.  The saliency detection problem

2.  A unifying framework for bottom-up
    saliency detection algorithms

3.  Ways to improve the performance
Look for the unique item
 Clap when you find it
Saliency Detection via Divergence Analysis: A Unified Perspective ICPR 2012
Saliency Detection via Divergence Analysis: A Unified Perspective ICPR 2012
Saliency Detection via Divergence Analysis: A Unified Perspective ICPR 2012
What is Saliency?
•  Visual salience (or visual saliency) is the
    distinct subjective perceptual quality
    which makes some items in the world
    stand out from their neighbors and
    immediately grab our attention

                Where to look?
Example of Stimulus



 Color       Orientation




Motion     Natural scene
Why We Care?
•    Adaptive image compression
•    Object-of-interest image segmentation
•    Automatic image thumbnail
•    (Class-independent) Object detection and recognition
•    Visual tracking
•    Automatic Image collage
•    Content-aware image resizing
•    Non-photorealistic rendering
•    Understanding mechanism of human visual attention
Problem Setting
•  Input: Image -> Output: Saliency map
Design Principles
•  Rarity
   –  [Bruce NIPS 05] [Zhang JOV 08] [Rahtu ECCV 10] [Klein ICCV 11] [Borji
       CVPR 12]
•  Local complexity
   –  [Kadir IJCV 01]
•  Contrast
   –  [Itti PAMI 98] [Harel NIPS 05] [Ma MM 03] [Achanta CVPR 09] [Achanta
       ICIP 10] [Cheng CVPR 11] [Goferman CVPR 10] [Perazzi CVPR 12]
•  Spectral
   –  [Hou CVPR 07] [Guo CVPR 08] [Hou PAMI 12] [Li PAMI 12]
•  Learning
   –  [Liu CVPR 07] [Judd ICCV 09] [Oliva ICIP 03] [Torralba Psycho.Rev 06]
Complexity!                         Contrast!
Surprise!                                Spectral!                Learning!
            Information!       Rarity!                     WTH?
Which one is better?
Main Result
•  Most of the bottom-up saliency detection
   algorithms can be rewritten in the form of
   divergence between probabilistic
   distributions learned from center and
   surround
Center-Surround Divergence
Kullback-Leibler Divergence
From Center to Surround
From Center to Surround
From Surround to Center
From Surround to Center
From Surround to Center
Symmetrised Divergence
Symmetrised Divergence
How to Choose Support?
Experimental Results
•  Datasets
  –  MSRA salient object detection dataset
  –  1000 groundtruth binary mask are available from
      [Achanta CVPR 09]
•  Evaluation metric
  –  Precision and recall curves
State-of-the-art
Saliency Detection Methods
–  Center to surround
   •  AIM [Bruce NIPS 05] SUN [Zhang JOV 08], SW [Rahtu ECCV
       10]
–  Surround to center
   •  CA [Goferman CVPR 10], AC [Achanta ICIP 10], FT [Achanta
       CVPR 09], LC [Zhai-ACMMM 06]
–  Symmetrised divergence
   •  HC, RC, [Cheng CVPR 11], IT [Itti PAMI 98], GB [Harel NIPS
      07]
–  Spectrum-based
   •  SR [Hou CVPR 07]
•  Rarity-based
   –  AIM: image specific
   –  SUN: image indep.
•  Rarity-based
   –  SW: Patch/window
       based surround +
       scale space analysis
•  Contrast-based
   –  GB: spatial weighting
      for adaptive surround
•  Contrast-based
   –  AC: adaptive surround
      support
•  Contrast-based
   –  RC: region-based
      center support
•  Contrast-based
   –  FT: color feature
   –  LC: intensity feature
Lessons Learned
•  Most of the bottom-up saliency detection
   algorithms are in fact closely related
  –  Not exhaustive, e.g., spectral-based methods
•  How to improve the performance?
  –  Richer features
  –  Less approximation
  –  Adaptive center/surround support
Future Work
Input image     Saliency Map      Error Map




              Method parameters
Saliency Detection via Divergence Analysis: A Unified Perspective ICPR 2012
Questions?
•  Comments or questions:

Jia-Bin Huang
jbhuang1@illinois.edu
https://netfiles.uiuc.edu/jbhuang1/www/
References
•  Saliency Detection via Divergence Analysis: An Unified Perspective
   J.B. Huang and N. Ahuja. ICPR, 2012
•  Frequency-tuned salient region detection
   R. Achanta, S. Hemami, F. Estrada, and S. Susstrunk., CVPR 2009
•  Saliency detection using maximum symmetric surround.
   R. Achanta and S. Susstrunk, ICIP, 2010.
•  State-of-the-art in visual attention modeling
   A. Borji and L. Itti. PAMI 2012
•  Saliency based on information maximization.
   N. Bruce and J. Tsotsos. NIPS, 2005
•  Global contrast based salient region detection.
   M. M. Cheng, G. X. Zhang, N. J. Mitra, X. Huang, and S. M. Hu. CVPR, 2011
•  The discriminant center-surround hypothesis for bottom-up saliency.
•  D. Gao, V. Mahadevan, and N. Vasconcelos. NIPS 2007
References
•  Context-aware saliency detection.
   S. Goferman, L. Zelnik-Manor, and A. Tal. CVPR, 2010.
•  Graph-based visual saliency.
   J. Harel, C. Koch, and P. Perona. NIPS, 2006
•  Saliency detection: A spectral residual approach.
   X. Hou and L. Zhang. CVPR, 2007
•  A model of saliency based visual attention for rapid scene analysis.
   L. Itti, C. Koch, and E. Niebur. PAMI 1998
•  Learning to predict where humans look.
   T. Judd, K. Ehinger, F. Durand, and A. Torralba. ICCV, 2009
•  Center-surround divergence of feature statistics for salient object detection.
   D. A. Klein and S. Frintrop. ICCV, 2011
•  Saliency detection based on frequency and spatial domain analyses
   J. Li, M. Levine, X. An, and H. He. BMVC 2011
References
•  Learning to detect a salient object
   T. Liu, J. Sun, N. N. Zheng, X. Tang, and H. Y. Shum, CVPR 2007
•  Contrast-based image attention analysis by using fuzzy growing
   Y. Ma and H. Zhang, ACM MM 2003
•  Top-down control of visual attention in object detection
   A. Oliva, A. Torralba, M. Castelhano, and J. Henderson. ICIP 2003
•  Segmenting salient objects from images and videos
   E. Rahtu, J. Kannala, M. Salo, and J. Heikkil., ECCV 2010
•  Computational versus psychophysical image saliency: A comparative
    evaluation study, A. Toet. PAMI 2011
•  Visual attention detection in video sequences using spatiotemporal cues
   Y. Zhai and M. Shah. ACM MM 2006
•  Sun: A bayesian framework for saliency using natural statistics
   L. Zhang, M. Tong, T. Marks, H. Shan, and G. Cottrell. JOV 2008

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Saliency Detection via Divergence Analysis: A Unified Perspective ICPR 2012

  • 1. Saliency Detection via Divergence Analysis Jia-Bin Huang Narendra Ahuja Electrical and Computer Engineering University of Illinois, Urbana-Champaign
  • 3. What this talk is about? 1.  The saliency detection problem 2.  A unifying framework for bottom-up saliency detection algorithms 3.  Ways to improve the performance
  • 4. Look for the unique item Clap when you find it
  • 8. What is Saliency? •  Visual salience (or visual saliency) is the distinct subjective perceptual quality which makes some items in the world stand out from their neighbors and immediately grab our attention Where to look?
  • 9. Example of Stimulus Color Orientation Motion Natural scene
  • 10. Why We Care? •  Adaptive image compression •  Object-of-interest image segmentation •  Automatic image thumbnail •  (Class-independent) Object detection and recognition •  Visual tracking •  Automatic Image collage •  Content-aware image resizing •  Non-photorealistic rendering •  Understanding mechanism of human visual attention
  • 11. Problem Setting •  Input: Image -> Output: Saliency map
  • 12. Design Principles •  Rarity –  [Bruce NIPS 05] [Zhang JOV 08] [Rahtu ECCV 10] [Klein ICCV 11] [Borji CVPR 12] •  Local complexity –  [Kadir IJCV 01] •  Contrast –  [Itti PAMI 98] [Harel NIPS 05] [Ma MM 03] [Achanta CVPR 09] [Achanta ICIP 10] [Cheng CVPR 11] [Goferman CVPR 10] [Perazzi CVPR 12] •  Spectral –  [Hou CVPR 07] [Guo CVPR 08] [Hou PAMI 12] [Li PAMI 12] •  Learning –  [Liu CVPR 07] [Judd ICCV 09] [Oliva ICIP 03] [Torralba Psycho.Rev 06]
  • 13. Complexity! Contrast! Surprise! Spectral! Learning! Information! Rarity! WTH?
  • 14. Which one is better?
  • 15. Main Result •  Most of the bottom-up saliency detection algorithms can be rewritten in the form of divergence between probabilistic distributions learned from center and surround
  • 18. From Center to Surround
  • 19. From Center to Surround
  • 25. How to Choose Support?
  • 26. Experimental Results •  Datasets –  MSRA salient object detection dataset –  1000 groundtruth binary mask are available from [Achanta CVPR 09] •  Evaluation metric –  Precision and recall curves
  • 27. State-of-the-art Saliency Detection Methods –  Center to surround •  AIM [Bruce NIPS 05] SUN [Zhang JOV 08], SW [Rahtu ECCV 10] –  Surround to center •  CA [Goferman CVPR 10], AC [Achanta ICIP 10], FT [Achanta CVPR 09], LC [Zhai-ACMMM 06] –  Symmetrised divergence •  HC, RC, [Cheng CVPR 11], IT [Itti PAMI 98], GB [Harel NIPS 07] –  Spectrum-based •  SR [Hou CVPR 07]
  • 28. •  Rarity-based –  AIM: image specific –  SUN: image indep.
  • 29. •  Rarity-based –  SW: Patch/window based surround + scale space analysis
  • 30. •  Contrast-based –  GB: spatial weighting for adaptive surround
  • 31. •  Contrast-based –  AC: adaptive surround support
  • 32. •  Contrast-based –  RC: region-based center support
  • 33. •  Contrast-based –  FT: color feature –  LC: intensity feature
  • 34. Lessons Learned •  Most of the bottom-up saliency detection algorithms are in fact closely related –  Not exhaustive, e.g., spectral-based methods •  How to improve the performance? –  Richer features –  Less approximation –  Adaptive center/surround support
  • 35. Future Work Input image Saliency Map Error Map Method parameters
  • 37. Questions? •  Comments or questions: Jia-Bin Huang [email protected] https://netfiles.uiuc.edu/jbhuang1/www/
  • 38. References •  Saliency Detection via Divergence Analysis: An Unified Perspective J.B. Huang and N. Ahuja. ICPR, 2012 •  Frequency-tuned salient region detection R. Achanta, S. Hemami, F. Estrada, and S. Susstrunk., CVPR 2009 •  Saliency detection using maximum symmetric surround. R. Achanta and S. Susstrunk, ICIP, 2010. •  State-of-the-art in visual attention modeling A. Borji and L. Itti. PAMI 2012 •  Saliency based on information maximization. N. Bruce and J. Tsotsos. NIPS, 2005 •  Global contrast based salient region detection. M. M. Cheng, G. X. Zhang, N. J. Mitra, X. Huang, and S. M. Hu. CVPR, 2011 •  The discriminant center-surround hypothesis for bottom-up saliency. •  D. Gao, V. Mahadevan, and N. Vasconcelos. NIPS 2007
  • 39. References •  Context-aware saliency detection. S. Goferman, L. Zelnik-Manor, and A. Tal. CVPR, 2010. •  Graph-based visual saliency. J. Harel, C. Koch, and P. Perona. NIPS, 2006 •  Saliency detection: A spectral residual approach. X. Hou and L. Zhang. CVPR, 2007 •  A model of saliency based visual attention for rapid scene analysis. L. Itti, C. Koch, and E. Niebur. PAMI 1998 •  Learning to predict where humans look. T. Judd, K. Ehinger, F. Durand, and A. Torralba. ICCV, 2009 •  Center-surround divergence of feature statistics for salient object detection. D. A. Klein and S. Frintrop. ICCV, 2011 •  Saliency detection based on frequency and spatial domain analyses J. Li, M. Levine, X. An, and H. He. BMVC 2011
  • 40. References •  Learning to detect a salient object T. Liu, J. Sun, N. N. Zheng, X. Tang, and H. Y. Shum, CVPR 2007 •  Contrast-based image attention analysis by using fuzzy growing Y. Ma and H. Zhang, ACM MM 2003 •  Top-down control of visual attention in object detection A. Oliva, A. Torralba, M. Castelhano, and J. Henderson. ICIP 2003 •  Segmenting salient objects from images and videos E. Rahtu, J. Kannala, M. Salo, and J. Heikkil., ECCV 2010 •  Computational versus psychophysical image saliency: A comparative evaluation study, A. Toet. PAMI 2011 •  Visual attention detection in video sequences using spatiotemporal cues Y. Zhai and M. Shah. ACM MM 2006 •  Sun: A bayesian framework for saliency using natural statistics L. Zhang, M. Tong, T. Marks, H. Shan, and G. Cottrell. JOV 2008

Editor's Notes

  • #2: Thanks for the introduction. I am Jia-Bin Huang. Today I am going to talk about some interesting facts about saliency detection.
  • #3: This is a joint work with Prof. Narendra Ahuja at the University of Illinois, Urbana-Champaign
  • #4: I will start with an overview of the problem. Then, introducing a unifying framework for bottom-up saliency detection algorithms. Later, we suggest ways to improve the performance.
  • #8: Let’s play a game first. Please clap when you see something different.
  • #9: Saliency is the distinct subjective quality which makes some items pop out from their neighbors and grab our attention. It guides us where to look.
  • #10: Here are some examples of stimulus.
  • #11: The reasons that this problem is important because it can facilitate numerous applications in computer vision and computer graphics.
  • #12: Here is the problem setting. Given an input image, our goal is to produce a saliency map locating the salient regions.
  • #13: There have been many design principles that guide the development of saliency detection algorithms. For example, rarity, complexity, contrast, spectral methods, and learning-based approaches.
  • #14: However, since some of the principles are inspired from psychological experiments, some are from intuitions, and others are purely computational, it’s often difficult to see their relations and more practically, which one is better?
  • #16: In this paper, we provide the bridges between these methods. Our claim is that most of the bottom-up saliency detection algorithms can be rewritten in the form of divergence between the probabilistic distributions learned from center and surround.
  • #18: Let’s start with KL-divergence. KL divergence is a contrast function between two probabilistic distributions. It has the following forms. It has many important operational meanings in detection, estimation, and information theory. In the following few slides, I will explicitly show the connections between various models.
  • #19: If we assume that the center support is a single pixel x_i, the KL-divergence from center to surround will become the so-called Shannon’s self-information. This class of saliency is called rarity-based saliency.
  • #20: If we take the difference between the self-information of center and surround, it yields the saliency in Rahtu’s paper at ECCV. If we make the assumption of feature channel independence, we can derive the saliency measure in Klein at ICCV.
  • #21: So how about switch the order? From the likelihood theory we know that the divergence can be rewritten as likelihood function. This forms the basics of contrast-based saliency methods.
  • #22: Assume that the distribution of the center follows Laplacian distributions. The saliency measure has this form.
  • #23: Similarly, assuming that the distribution is Gaussian. Using various approximation approaches gives rises to various measures.
  • #24: Now let’s look at some symmetrised divergence measure. The first one is the symmetric KL divergence. This measure has been widely used from feature selection. In the context of saliency detection, it corresponds to combine local and global rarity. Lambda divergence is another symmetric measure. It corresponds to the mutual information-based saliency.