Camouflage Detection

An introductionPresented by: Ani Starrenburg

General Camouflaging Strategies

Cryptic Camouflage

Little Button Quail Traditional US Army Camouflage Pattern

General Camouflaging Strategies

Mimicry

Dronefly Rose Greenbow,Confederate Spy

General Camouflaging Strategies

Disruption

Sumatran Tiger Dazzle Camouflage

General Camouflaging Strategies

Countershading

Impala Non-Countershaded Warship

Translucence/Transparency

Seawasp Invisibility Cloak

General Camouflaging Strategies

Detecting Camouflaged Objects:

Camouflage Detection Methods

Standard Object Detection Methods Edge Detection Models Contrast Energy Detection Model

Motion Detection Correlation Models Gradient Models Energy Models

Edge Detectors:

Gradient Laplacian LaplacianWith Gaussian

Gaussian

Canny Detector

Optimal Edge Detector Multiple Stage Algorithm

Perform Gaussian smoothing Find edge strengths

|G| = |Gx| + |Gy| Detection of edge direction

theta = invtan(Gy/Gx) Relate edge direction to

a direction that can be traced

in an image Apply non-maximum

suppression Use hysteresis to eliminate streaking

LaPlacian or LoG

Smooth with a Gaussian mask Calculate the second derivatives Search for zero crossings

Or Convolve the image with the

Laplacian of the Gaussian

Contrast Energy (CE) Model

Uses the output signal from similarly-orientedodd o[x] and even e[x] filters.

Energy function is defined as:E2(x) = e2(x) + o2(x)

Always positive

Shows high output when o(x), e(x) or both are high.

Camouflage DetectionMethods to be Discussed

Convexity-Based Detection – exploits the principle of countershading to detect camouflaged objects

Texture Detection – intensive texture analysis distinguishes camouflaged object from background. Also, uses Canny detector to bring up edges

Motion Breaks Camouflage

Region of common velocity is perceivedAs a unit and stands out against the staticbackground

Reichardt Correlation Model

Computes motion as the ratio of the partial derivatives of the input image brightness with respect to space and time.

Two spatially-separate detectors. Output of one of the detectors is delayed. The two outputs are multiplied to determine if there is

a correlation.

Multichannel Gradient Model

Uses multiple channels of higher derivatives

The more derivatives used lowers the chance of that all will be zero at the same time

Uses a least sqaures approximation of the derivatives

Motion Energy Model

Uses two sets of oriented detectors(leftwards and rightwards), each composed of an odd and an even filter.

Energy is calculated by summing the squares of the two similarly-oriented filters.

Calculate opponent energy (difference of leftward and rightward results)

Normalize by dividing by static energy to give velocity estimates

An aside: Research on Active Camouflage

Animals that can escape edge detection

Animals that can camouflage motion

To Do List:

Apply edge detectors and contrast energy detectors to camouflaged and illusory images and view results.

Research visual models developed from observing animal behavior and development.

Research studies in psychology for further understanding of vision process.

Is there a core visual system?

CAMOUFLAGE

ART

Bibliography Motion Illusions and Active Camouflage, Lewis Dartnell

,http://www.ucl.ac.uk/~ucbplrd/motion/motion_middle.html Canny Edge Detection Tutorial, Bill Green,

http://www.pages.drexel.edu/~weg22/can_tut.html Honeybee, http://www.gpnc.org/honeybee.htm Ground-dwelling birds, http://www.birdobservers.org.au/ground_birds.htm Sumatran tiger, http://www.saczoo.com/3_kids/20_camouflage/camouflage_disruptive.htm Biomimicry, http://www.wordspy.com/words/biomimicry.asp Countershading, http://www.shipcamouflage.com/ships2_3_43_countershading.htm Translucence, http://www.gla.ac.uk/ibls/DEEB/teg/project_pages/counter_shading.htm Canny Edge Detection,

http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/OWENS/LECT6/node2.html Optical Camouflage, http://projects.star.t.u-tokyo.ac.jp/projects/MEDIA/xv/VRIC2003.pdf Multi-Channel Gradient Model, http://www.psychol.ucl.ac.uk/pmco/McGM.html