Appendix+a OpenCV+Tutorial+v012

8/8/2019 Appendix+a OpenCV+Tutorial+v012

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Appendix 2

Introduction to OpenCV

Speaker:


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Contents

Introduction

Image Displaying

Image Copying

OpenCV Library


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Introduction

Overview

OpenCV is an open source computer vision library

It implements thousands of high-level functions for

computer vision and image processing.

Each function name in OpenCV starts with cv :

cvCreateImage, cvSobel, cvAdd,

It includes many high-level datatypes, such as, Sets,Trees, Graphs, and Matrices. . .


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Introduction

Why OpenCV?

Computer vision market is large and still

continues to grow.

There is no standard APIs like OpenGL forgraphics.

Research Code

Very expensive commercial toolkits

Specialized solution bundled withhardware

Standard library would simplify development of

new applications and solutions much easier.

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Introduction

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Introduction

Library Design

Initial Goal: build high-level and ready-to-use

components, such as gesture recognition.

But, the computer vision problem is alwayscomplex and hard to be solved directly.

The design is to split complex problem into

building block which is a function in OpenCV

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Introduction

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No free libraries could do this.

We have to do it ourselves.


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Introduction

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Introduction

OpenCV Installation

Download the OpenCV 2.1 from website

http://sourceforge.net/projects/opencvlibrary/

Execute the file OpenCV-2.1.0-win32-vs2008.exeto install the OpenCv 2.1

VC2008 Installation

Download the VC2008 from website

Install the VC2008 on your computer


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Introduction

Project Creation

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Introduction

Project Creation

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Introduction

Environment Setup

Include the header files: C:\Program

Files\OpenCV2.1\include\opencv


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Introduction

Environment Setup

Include the header files: C:\Program

Files\OpenCV2.1\include\opencv

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Introduction

Environment Setup

Include the library files: C:\Program

Files\OpenCV2.1\lib

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Introduction

Environment Setup

Input the library files to project: cv210.lib

highgui210.lib cxcore210.lib cvaux210.lib

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Introduction

Environment Setup

Input the library files to project: cv210.lib

highgui210.lib cxcore210.lib cvaux210.lib

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Image Displaying

Application

Load the well-known lena.jpg from the file

Display the loaded image on the window

Save the loaded image as result.jpg


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Image Displaying

Lena Application: Sample Code

#include "cv.h"

#include "highgui.h "

int _tmain(int argc, _TCHAR* argv[]){

..

return 0;}/* End of main body */


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Image Displaying

Lena Application: Sample Code


IplImage* pImage1=NULL;

pImage1 = cvLoadImage("lena.jpg");

cvNamedWindow("Lena", 1);

cvShowImage("Lena", pImage1);

cvWaitKey(0);

if(pImage1 != NULL)

cvSaveImage(result.jpg, pImage1);

return 0;

}/* End of main body */


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Image Copying

IplImage Data Structure

typedef struct_IplImage {

int nChannels; /* support 1,2,3 or 4 channels */

int depth; /* pixel depth in bits*/

int width; /* image width in pixels */

int height; /* image height in pixels */

char *imageData; /* pointer to aligned image data */

} IplImage;


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Image Copying

IplImage Data Structure

nDepths: data type of the channel

imageData: one-dimensional array

IPL_DEPTH_8U,

IPL_DEPTH_8S,

IPL_DEPTH_16S,

IPL_DEPTH_32S,

IPL_DEPTH_32FIPL_DEPTH_64F


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Image Copying

Image Creating: cvCreateImage();

IplImage* pImage2 = NULL;

pImage2 = cvCreateImage(cvSize(512, 512), IPL_DEPTH_8U, 1);


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Image Copying

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#include "cv.h"

#include "highgui.h "


..

unsigned char* ptr1 = (unsigned char*) pImage1->imageData;


..

return 0;

}/* End of main body */


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Image Copying

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Image Copying

Image Data Indexing

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offset: i+ j*width R offset: 3*(i+ j*width) + 0G offset: 3*(i+ j*width) + 1B offset: 3*(i+ j*width)+2


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Image Copying



int width = pImage1->width;

int height= pImage1->height;

for(int h=0; h < height; h++)

for(int w=0; w < width; w++){

int sum = 0;

sum += ptr1[3 * (w + h * width) + 0];

sum += ptr1[3 * (w + h * width) + 1];sum += ptr1[3 * (w + h * width) + 2];

ptr2[w + h * width] = sum / 3;

}/* End of for-loop */


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Image Copying


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OpenCV Library

Description

There are three main OpenCV libraries

cxcore library

cv library

highgui library

The detailed documentation can be found through

the website.

\docs\index.htm

There are many available samples codes for

testing


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OpenCV Library

cxcore Library

Basic Data/Support Linear Algebra Structures CvPoint :2D point with integer coordinates

CvPoint2D32f:2D point with floating-point coordinates CvMat :Multi-channel matrix

IplImage: IPL image header

Operations

IplImage* cvCreateImage( CvSize size, int depth, intchannels );

IplImage* cvCloneImage( const IplImage* image );

void cvSetImageROI( IplImage* image, CvRect rect );


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OpenCV Library

cv Library

It includes many useful algorithms Image Processing

Structural Analysis

Motion Analysis Algorithm

Algorithms void cvCanny : for edge-detection

void cvGoodFeaturesToTrack: determine strong corners on

image void cvCvtColor :Converts image from one color space to

another


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OpenCV Library

Edge-detection Segmentation

Histogram


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OpenCV Library

Highgui Library It includes operations for I/O manipulation

Simple GUI

Loading and Saving Images

Video I/O

CvCapture* capture = 0;

capture = cvCaptureFromCAM() / cvCaptureFromAVI()

IplImage* frame = 0;

frame = cvQueryFrame(capture );


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OpenCV Library

Useful Links

OpenCV for Linux : basic tutorial

http://easynews.dl.sourceforge.net/sourceforge/opencvlibra

ry/ippocv.pdf

Overview of all the capabilities of OpenCV

http://www.intel.com/research/mrl/research/opencv/overvie

w.htm


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Appendix+a OpenCV+Tutorial+v012