2007 Theo Schouten 1

Introduction

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Human Eye

•6-7 106 Cones, 120 106 Rods•Reaction time: 0.1 sec (enough for transferring 100 nerve stimuli)•Parallel processing by 1010 nerve cells (neurons)•Adjustment to light intensity (factor 1010)•Stereo: 2 eyes and their continuous movement, focusing•Continuous assimilation of moving images

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Visual effects

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Steps in image processing

• Production (CCD camera, CT, MRI ) • Storage, transmission and compression • Transformation eg to a Fourier or Wavelet space • Restoration, e.g. lens distortions or movement • Enhancement: making suitable for an application • Segmentation: finding (parts of) relevent objects

– finding edges: local deviations in an image – finding surface areas: local similarities

• Describing and measuring of regions and objects • Image understanding (Pattern recognition, classical,

neural networks, AI)

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Special methods

• 2 and 3 D Computed Tomography (CT) images to make it possible to view the interior of an object.

• binary images, e.g. mathematical morphology • color and in general multispectral images • texture (fine structures on a surface)• 3-D reconstruction out of stereo images • video processing (movement, 3-D)• 3D image processing

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Computing challenges

• the large amount of data • high complexity of algorithms• high speed requirements

– parallel machines, algorithms– special purpose chips, CPU’s

• real-time requirements– image recorders, robots, production machines

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Optimizing code/* slow.c */

#define SIZE 4096float imin[SIZE][SIZE], imout[SIZE][SIZE];

int main(int argc, char **argv){  int i, j, k, l;/* initialize image */  for(i=0; i < SIZE; i++) for(j=0; j < SIZE; j++) imin[j][i] = (i+j) % 256;/* average each pixel with its neighbours */  for(i=0; i < SIZE; i++) {    for(j=0; j < SIZE; j++) {      if( i == 0 || j == 0 ) imout[j][i] = imin[j][i];      else if( i == SIZE-1 || j == SIZE-1 ) imout[j][i] = imin[j][i];      else {        imout[j][i] = 0;        for(k=-1; k < 2 ; k++) for(l=-1; l < 2; l++) imout[j][i] += imin[j+l][i+k];        imout[j][i] /= 9 ;

}}}}

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Relation other science fields

• Signal Analysis; 1D signal. • Geometry; position, orientation and size of objects from 3-D measurements• Linear Algebra • Estimation Theory; eg compression of images or in determining the

movement of objects. • Statistical Pattern recognition; classification• Syntactical Pattern recognition; structure of an image• Artificial Intelligence; representation and manipulation of knowledge

information that is extracted from images. • Real Time Systems; interaction with other machines. • System and Computer Architecture; parallel (1 CPU per pixel); special

processors • Computer Graphics; for projecting the images and showing the results of

the manipulations • User Interfaces; for good interaction with the software systems used for

image manipulations.

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Uses of image processing

• Medical Imaging • Machine en Robot vision (industrial production and

inspection )• Remote Sensing (satellite and aerial photos) • graphical and game industry, image editing in

combination with computer graphics • consumer photo and video editing

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Integrated Examination

• 4 assignments• 1st individual, rest in groups• working towards a goal• all assignments must have been handed in• final grade is average if all grades are 5 or more

– otherwise the lowest grade

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FEED

Fast Exact Euclidean Distance transformationJoint research with Egon van den Broek en Harco Kuppens

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Video Surveillance

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Depth from floor contact