Intel OPEN SOURCE COMPUTER VISION LIBRARY

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OpenCV

• Intel OPEN SOURCE COMPUTER VISION LIBRARY

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OpenCV Functionality(more than 350 algorithms)

• Basic structures and operations
• Image Analysis
• Structural Analysis
• Object Recognition
• Motion Analysis and Object Tracking
• 3D Reconstruction

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Basic Structures and Operations

• Multidimensional array operations
• Dynamic structures operations
• Drawing primitives
• Utility functions

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Image Analysis

• Thresholds
• Statistics
• Pyramids
• Morphology
• Distance transform
• Flood fill
• Feature detection
• Contours retrieving

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Image Thresholding

• Fixed threshold
• Adaptive threshold

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Image Thresholding Examples
Source picture
Fixed threshold
Adaptive threshold
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Statistics
Victor Eruhimov In addition to simple norm
calculation, there is a function that finds the
norm of the difference between two images.

• min, max, mean value, standard deviation over the
  image
• Norms C, L1, L2
• Multidimensional histograms
• Spatial moments up to order 3 (central,
  normalized, Hu)

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Image Pyramids

• Gaussian and Laplacian

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Pyramid-based color segmentation
On still pictures
And on movies
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Feature Detection

• Fixed filters (Sobel operator, Laplacian)
• Optimal filter kernels with floating point
  coefficients (first, second derivatives,
  Laplacian)
• Special feature detection (corners)
• Canny operator
• Hough transform (find lines and line segments)
• Gradient runs

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Canny Edge Detector
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Hough Transform
Detects lines in a binary image

• Probabilistic Hough Transform

• Standard Hough Transform

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Another Sample of the Hough Transform Using
Source picture
Result
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Using contours and geometry to classify shapes

• Given the contour classify the geometrical figure
  shape (triangle, circle, etc)

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Line and ellipse fitting

• Algebraic ellipse fitting
• Fitting lines by m-estimators

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Software Requirements

• Win32 platforms
• Win9x/WinNT/Win2000/WinXP
• C Compiler (makefiles for Visual C 6.0,Intel
  C Compiler 5.x,Borland C 5.5, Mingw GNU C/C
  2.95.3 are included ) for core libraries
• Visual C to build the most of demos
• DirectX 8.x SDK for directshow filters
• ActiveTCL 8.3.3 for TCL demos
• IPL 2.2 for the core library tests
• Linux/NIX
• C Compiler (tested with GNU C/C 2.95.x, 2.96,
  3.0.x)
• TCL 8.3.3 BWidgets for TCL demos
• Video4Linux Camera drivers for most of demos
• IPL 2.2 for the core library tests

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Data Types

• Image (IplImage)
• Matrix (CvMat)
• Histogram (CvHistogram)

Multi-dimensional array
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Portable GUI library (HighGUI)

• Reading/Writing images in several formats
  (BMP,JPEG,TIFF,PxM,Sun Raster)
• Creating windows and displaying images in it.
  HighGUI windows remember their content (no need
  to implement repainting callbacks)
• Simple interaction facilities trackbars, getting
  input from keyboard
• and mouse (new in Win32 version).

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Primitive Functions

• Open Window
• cvvNamedWindow( "image", 1 )
• Create Image
• IplImage work cvCreateImage( cvsize, depth,
  channel )
• Load Image
• IplImage img cvvLoadImage( filename )
• Copy Image
• img cvCloneImage( img )
• Show Image
• cvvShowImage( "image", img ) // show image in
  the window "image
• Release Image
• cvReleaseImage( img ) // release both images

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IplImage data Structure

• In OpenCV Library Reference Manaul
• typedef struct _IplImage
• .. .. ..
• char colorModel4
• int width
• int height
• int imageSize / useful size in bytes /
• char imageData / pointer to aligned image /
• .. .. ..
• IplImage

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Other Functions

• Most of functions are explained in
  OpenCVReferenceManual.pdf
• cvKMeans ( int numClusters, CvVect32f samples,
  int numSamples, int vecSize, CvTermCriteria
  termcrit, int cluster )
• cvCanny( IplImage img, IplImage edges, double
  lowThresh, double highThresh, int
  apertureSize3 )

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An example

• include ltstdio.hgt
• include ltmath.hgt
• include ltstring.hgt
• include "cv.h" // include core library
  interface
• include "highgui.h" // include GUI library
  interface
• class ImageProcessor
• IplImage img // Declare IPL/OpenCV image
  pointer
• public
• ImageProcessor(CString filename, bool
  displaytrue)
• img cvvLoadImage( filename ) // load
  image
• if (display)
• cvvNamedWindow( "Original Image", 1 )
  // create a window

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cvapp.h (cont.)

• void display()
• cvvNamedWindow( "Resulting Image", 1 ) //
  create a window
• cvvShowImage( "Resulting Image", img ) //
  display the image on window
• void execute()
• ImageProcessor()
• cvReleaseImage( img )

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cvapp.c

• include "stdafx.h"
• include "cvapp.h"
• ImageProcessor proc 0
• // Should have been declared as
• // void process(IplImage img)
• // but we will use it as a callback
• // in the next version.
• void process(void img)
• IplImage image reinterpret_castltIplImagegt(im
  g) // img must point to an IplImage
• cvErode( image, image, 0, 2 )
• void ImageProcessorexecute()
• process(img)

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Reference

• http//sourceforge.net/projects/opencvlibrary/
• Slides and Sample Programs
• CVPR01_course.zip
• http//www-scf.usc.edu/csci574/opencv/
• OpenCV Library Reference Manual
• OpenCVRefMan.pdf
• Installation of OpenCV
• InstallOpenCV.doc