1.1 Description of a Sampled Imager 3
1.2 Description of the Sampling Process 6
1.3 Linearity and Shift Invariance 9
1.4 Signal Reconstruction 13
1.5 Three Ways of Viewing the Sampling Process 15
1.5.1 The displayed image as the sum of its parts 16
1.5.2 The display as a filter of the image samples 18
1.5.3 The display as a filter of the sampled image 20
1.6 The Sampling Theorem 24
1.6.1 Theory 24
1.6.2 Example 26
1.6.3 Discussion 29
Bibliography 29
Chapter 2 Fourier Integral Representation of an Optical Image 31
2.1 Linear Shift-Invariant Optical Systems 31
2.2 Equivalence of Spatial and Frequency Domain Filters 34
2.3 Reducing LSI Imager Analysis to One Dimension 36
2.4 Perspectives on One-Dimensional Analysis 42
2.5 Imager Modulation Transfer Functions 45
2.5.1 Imager components 45
2.5.2 Line-of-sight jitter 47
2.5.2.1 Reduction of line-of-sight jitter by eye
tracking 50
2.5.2.2 Effect of temporal sampling on line-of-sight
jitter 52
2.5.3 Electronic stabilization 53
2.5.4 Motion blur 55
2.5.5 Field replication 56
2.5.6 Analog electronic filters 56
2.5.7 Display MTF 57
Bibliography 59
3.1 Fourier Transform of a Sampled Image 63
3.2 The Sampled Imager Response Function 67
3.3 Examples of Sampled Imager Response Functions 69
3.3.1 Example 1: The pictures of Lena in Chapter 1 69
3.3.2 Example 2: Effect of changing sample rate 71
3.3.3 Example 3: Midwave thermal imager 79
3.3.4 Example 4: Two-dimensional SIR example 81
Bibliography 85
6.1 Specifying and Evaluating Field Performance 118
6.2 Factors That Influence Target Identification 120
6.3 Measuring Target Signatures 121
6.4 Experimental Procedure 122
6.5 Field Test Procedure 125
6.6 Test Sets Other Than Tactical Vehicles 127
6.7 Field Testing Using Bar Targets 129
7.1 Imager Evaluation Procedure 132
7.2 Modeling Gain, Level, and the User Interface 134
7.3 Observer Vision 138
7.4 Predicting Probability of Identification 143
7.4.1 Comparing experimental data to model predictions 145
7.5 Test Sets Other Than Tactical Vehicles 146
Bibliography 147
Chapter 8 Quantifying the Effect of Aliasing on Visual
Task Performance 149
8.1 Model Treatment of Spatial Noise 150
8.2 Treatment of Temporal Noise in Detectivity Versus
Photon-Counting Models 152
8.3 Relating Target and Imager Coordinate Systems 155
8.4 Spatial Scaling of Aliasing Noise 161
Bibliography 163
9.1 Effective Blackbody Temperature 168
9.2 Signal and Noise in the Detectivity Model 172
9.3 Thermal Imager Contrast Threshold Function 175
9.4 Adding Aliasing Noise 177
9.5 Predicting Range Performance 179
9.6 Modeling Contrast Enhancement and Boost 180
9.7 Minimum Resolvable Temperature 182
9.7.1 Predicting minimum resolvable temperature 183
9.7.2 Predicting sampled imager minimum resolvable temperature 187
9.7.3 Improving the minimum resolvable temperature procedure 190
Bibliography 191
10.1 Calculating Target Set Contrast 193
10.2 System Contrast Threshold Function 196
10.2.1 Interlace 200
10.2.2 Snapshot and frame integration 201
10.3 Predicting Range Performance 202
Bibliography 203
Part III Applications
Chapter 11 Computer Programs and Application Data 207
11.1 Optics Modulation Transfer Function 208
11.1.1 Thermal imagers 208
11.1.2 Imagers of reflected light 211
11.2 Display Modulation Transfer Function 213
11.2.1 Cathode ray tubes 213
11.2.2 Liquid crystal displays 216
11.2.3 Display interface format 218
11.3 Atmospheric Transmission and Turbulence 218
11.3.1 Atmosphere in the reflective model 219
11.3.2 Atmosphere in the thermal model 221
11.3.3 Atmospheric turbulence 223
11.4 Detector Calculations 223
11.4.1 Detector noise 223
11.4.2 Detector modulation transfer function 226
11.5 Computer Program Description 227
11.6 Imager Analysis Using the Programs 235
11.6.1 Imager resolution 235
11.6.2 System contrast threshold function 236
11.6.3 Range plots 237
References 240
Bibliography 240