Image acquisition and pre-processing for machine vision

750 Pages·2010·36.35 MB·English

by  P K Sinha

Bellingham, Washington USA
Library of Congress Cataloging-in-Publication Data

Sinha, P. K. (Pradip K.), 1947-
Image acquisition and preprocessing for machine vision systems / Pradip K. Sinha.
p. cm. -- (Press monograph ; 197)
Includes bibliographical references and index.
ISBN 978-0-8194-8202-0
1. Computer vision. 2. Identification. 3. Electronic data processing--Data preparation.
I. Title.
TA1634.S56 2012
006.3'7--dc22
2010038733

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Copyright © 2012 Society of Photo-Optical Instrumentation Engineers

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Cover image courtesy of Eastman Kodak, Rochester, NY

Printed in the United States of America.
First printing
ToNatalie,Michael,andlateMargotJane

Contents
Preface................................................................................................................ xv
Acknowledgments...............................................................................................xvii
AcronymsandAbbreviations............................................................................. xix
Chapter1 Introduction........................................................................................ 1
1.1 Acquisition......................................................................................................... 1
1.2 Preprocessing..................................................................................................... 3
1.3 AnalysisandMeasurement........................................................................... 5
1.4 OverviewofText.............................................................................................. 8
References....................................................................................................................... 11
Chapter2 HumanVision..................................................................................... 13
2.1 SourcesofLight............................................................................................... 13
2.2 TheHumanEye................................................................................................ 15
2.3 StimulusMeasurement................................................................................... 18
2.4 BrightnessThresholds.................................................................................... 24
2.4.1 Absolutethreshold........................................................................... 24
2.4.2 Differentialthreshold...................................................................... 25
2.4.3 Adaptation.......................................................................................... 26
2.5 Contrast............................................................................................................... 27
2.6 VisualAcuity..................................................................................................... 30
2.7 Flicker.................................................................................................................. 31
2.8 Spatio-TemporalEffects................................................................................ 32
References....................................................................................................................... 35
Chapter3 Image-FormingOptics......................................................................... 39
3.1 OpticalGlass...................................................................................................... 40
3.2 GeometricalOptics.......................................................................................... 41
3.3 LensEquations.................................................................................................. 44
3.3.1 Simplethinlens................................................................................ 44
3.3.2 Compoundthinlens........................................................................ 46
3.3.3 Thicklens........................................................................................... 48
3.3.3.1 Balllens............................................................................. 48
vii
viii Contents
3.3.3.2 Cylindricallens................................................................ 48
3.3.3.3 Condenserlens................................................................. 49
3.3.3.4 Fresnellens....................................................................... 50
3.3.3.5 Microlenses...................................................................... 50
3.3.3.6 Extensiontube.................................................................. 50
3.4 ApertureStop, f-Number,andSpeed....................................................... 52
3.5 FocusingandDepthofField........................................................................ 59
3.6 ResolvingPower............................................................................................... 60
3.7 Aberration........................................................................................................... 65
3.7.1 Monochromaticaberrations......................................................... 65
3.7.1.1 Sphericalaberrations..................................................... 65
3.7.1.2 Astigmatism...................................................................... 66
3.7.1.3 Coma................................................................................... 66
3.7.1.4 Fieldcurvature................................................................. 66
3.7.1.5 Distortion........................................................................... 66
3.7.2 Chromaticaberrations.................................................................... 68
3.8 OpticalCoatings............................................................................................... 69
3.9 OpticalFilters.................................................................................................... 70
3.9.1 Absorptionfilters............................................................................. 71
3.9.2 Interference(bandpass)filters..................................................... 71
3.10 Plasticlens.......................................................................................................... 72
References....................................................................................................................... 73
Chapter4 SceneIllumination............................................................................... 75
4.1 RadiantSources................................................................................................ 75
4.2 TypesofIlluminators...................................................................................... 77
4.3 OpticalPropertiesofTargets........................................................................ 78
4.3.1 Reflectivematerials......................................................................... 78
4.3.2 Transmissivematerials................................................................... 79
4.3.3 Absorptivematerials....................................................................... 80
4.4 LightingMethods............................................................................................. 80
4.4.1 Frontlighting..................................................................................... 80
4.4.2 Backlighting...................................................................................... 81
4.4.3 Specularillumination..................................................................... 82
4.4.4 Beamsplitterandsplitmirror....................................................... 83
4.4.5 Retroreflector.................................................................................... 83
4.4.6 Structuredlighting........................................................................... 85
4.5 PolarizationofLight....................................................................................... 85
4.6 FiberOpticLighting........................................................................................ 92
4.6.1 Lightgathering................................................................................. 95
4.6.2 Transmissioncharacteristics........................................................ 97
References....................................................................................................................... 101
Contents ix
Chapter5 ImageSensors....................................................................................103
5.1 Photogeneration................................................................................................ 104
5.1.1 Criticalwavelength......................................................................... 104
5.1.2 Absorptioncoefficient.................................................................... 105
5.2 Photoconductor................................................................................................. 107
5.3 Photodiode.......................................................................................................... 109
5.4 CMOSImageSensor...................................................................................... 115
5.5 Metal-OxideGate............................................................................................. 118
5.6 Charge-CoupledDevices............................................................................... 121
5.6.1 Charge-transferefficiency............................................................. 125
5.6.2 Blooming............................................................................................ 127
5.6.3 Illuminationgeometry.................................................................... 127
5.7 Line-ScanImaging.......................................................................................... 127
5.8 Area-ScanImaging.......................................................................................... 130
5.9 RelatedTopics................................................................................................... 136
5.9.1 Pixelsize............................................................................................. 136
5.9.2 Color-filterarray.............................................................................. 137
5.9.3 Noise.................................................................................................... 139
5.9.4 CMOSversusCCD......................................................................... 140
5.9.5 Scanpattern....................................................................................... 142
5.9.6 Pixelordering.................................................................................... 145
5.9.7 Incidentphotons............................................................................... 146
Appendix5A:SemiconductorProperties............................................................. 150
5A.1 OpticalMaterials.............................................................................. 151
5A.2 DopingofSemiconductors........................................................... 151
5A.3 CarrierGeneration........................................................................... 152
5A.4 OpticalSensors................................................................................. 154
5A.5 SemiconductorTerminology........................................................ 154
References....................................................................................................................... 156
Chapter6 ImagingHardware...............................................................................161
6.1 ImageDisplay................................................................................................... 161
6.2 LiquidCrystalDisplay................................................................................... 169
6.3 Framegrabber..................................................................................................... 173
6.3.1 Analogfrontend.............................................................................. 179
6.3.2 Timingpulses.................................................................................... 179
6.3.3 Pixelclock.......................................................................................... 179
6.3.4 Gray-leveldigitization................................................................... 180
6.3.5 Look-uptable.................................................................................... 180
6.3.6 Imagestore......................................................................................... 181
6.3.7 Dedicatedprocessor........................................................................ 182
6.3.8 Videosamplingfrequency............................................................ 182
x Contents
6.4 LatencyParameters.......................................................................................... 184
6.4.1 Capturelatency................................................................................. 185
6.4.2 Transferlatency................................................................................ 190
6.4.3 Effectsoflatency............................................................................. 191
6.5 Resolution........................................................................................................... 194
6.5.1 Gray-levelresolution...................................................................... 194
6.5.2 Pixelresolution................................................................................. 194
6.5.3 Spatialresolution............................................................................. 194
6.5.4 Assessmentofresolution.............................................................. 198
References....................................................................................................................... 201
Chapter7 ImageFormation.................................................................................203
7.1 FieldofView..................................................................................................... 208
7.2 DepthofField.................................................................................................... 211
7.3 ImageIntensity.................................................................................................. 215
7.4 ImageFunctions .............................................................................................. 221
7.4.1 Point-spreadfunction..................................................................... 222
7.4.2 Line-spreadfunction....................................................................... 227
7.4.3 Edge-spreadfunction...................................................................... 227
7.4.4 Opticaltransferfunction................................................................ 228
7.4.5 MTFandcontrast............................................................................. 230
7.5 ImageModeling................................................................................................ 234
7.5.1 Wavefrontmodel............................................................................. 235
7.5.2 Diffraction ......................................................................................... 237
7.6 LensMTF........................................................................................................... 241
7.6.1 Resolution.......................................................................................... 251
7.6.2 Imagequality..................................................................................... 255
7.7 SensorMTF....................................................................................................... 261
7.7.1 SpatialMTF....................................................................................... 261
7.7.2 DiffusionMTF.................................................................................. 266
7.7.3 Charge-transferMTF...................................................................... 271
References....................................................................................................................... 279
Chapter8 CameraCalibration.............................................................................283
8.1 Projection............................................................................................................ 284
8.2 IdealIntrinsicModel....................................................................................... 289
8.3 ExtrinsicModel................................................................................................ 292
8.3.1 Translation.......................................................................................... 294
8.3.2 Rotation............................................................................................... 294
8.4 GeneralCameraModel.................................................................................. 295
8.5 TsaiCalibration................................................................................................ 298
8.5.1 Cameramodel................................................................................... 298
8.5.2 Scalingandorigintransfer............................................................ 300