This book examines contrast sensitivity of the human visual system--concerning the eye's ability to distinguish objects from each other or from the background--and its effects on the image-forming process. The text provides equations for determining various aspects of contrast sensitivity, in addition to models (mathematical expressions) that can easily be adapted for practical applications.

1 Introduction 1 References 5 2 Modulation threshold and noise 7 2.1 Introduction 2.2 Psychometric function 8 2.3 Basic properties of image noise 15 2.4 Effect of noise on modulation threshold 18 2.5 Summary and conclusions 22 References 22 3 Model for the spatial contrast sensitivity of the eye 25 3.1 Introduction 25 3.2 Outline of the model 25 3.3 Optical MTF 27 3.4 Photon noise 29 3.5 Neural noise 31 3.6 Lateral inhibition 32 3.7 Monocular versus binocular vision 36 3.8 Complete model 36 3.9 Comparison with measurements 38 3.9.1 Measurements by DePalma and Lowry 38 3.9.2 Measurements by Patel 39 3.9.3 Measurements by Robson 40 3.9.4 Measurements by van Nes and Bouman 3.9.5 Measurements by Campbell and Robson 44 3.9.6 Measurements by Watanabe et al. 45 3.9.7 Measurements by Sachs et al. 46 3.9.8 Measurements by van Meeteren and Vos 48 3.9.9 Measurements by Howell and Hess 49 3.9.10 Measurements by Virsu and Rovamo 50 3.9.11 Measurements by Carlson 51 3.9.12 Measurements by Rovamo et al. (1992) 52 3.9.13 Measurements by Rovamo et al. (1993a) 54 3.9.14 Measurements by Rovamo et al. (1993b) 55 3.9.15 Survey of the measurements 56 3.10 Summary and conclusions 57 Appendix A. Photon conversion factor 58 References 62 4 Extension of the contrast sensitivity model to extra-foveal vision 65 4.1 Introduction 65 4.2 Density distribution of cones and ganglion cells 66 4.2.1 Geometrical relations 66 4.2.2 Cone density distribution 67 4.2.3 Ganglion cell density distribution 69 4.3 Effect of eccentricity on the different constants used in the model 4.3.1 Effect of eccentricity on resolution 72 4.3.2 Effect of eccentricity on neural noise 74 4.3.3 Effect of eccentricity on lateral inhibition 75 4.3.4 Effect of eccentricity on quantum efficiency 76 4.3.5 Effect of eccentricity on the maximum integration area 77 4.4 Comparison with measurements 78 4.4.1 Measurements by Virsu and Rovamo 79 4.4.2 Measurements by Robson and Graham 81 4.4.3 Measurements by Kelly 83 4.4.4 Measurements by Mayer and Tyler 84 4.4.5 Measurements by Johnston 85 4.4.6 Measurements by Pointer and Hess 86 4.4.7 Survey of the measurements 88 4.5 Summary and conclusions 89 References 90 5 Extension of the contrast sensitivity model to the temporal domain 91 5.1 Introduction 91 5.2 Generalization of the spatial contrast sensitivity model 92 5.3 Temporal filter functions 93 5.4 Spatiotemporal contrast sensitivity measurements 94 5.5 Temporal contrast sensitivity measurements 98 5.6 Effect of a surrounding field 100 5.7 Effect of retinal illuminance and field size on the time constants 5.8 Flicker sensitivity: Ferry-Porter law 110 5.9 Temporal impulse response 114 5.10 Summary and conclusions 116 References 117 6 Effect of nonwhite spatial noise on contrast sensitivity 121 6.1 Introduction 121 6.2 Model for the masking effect of nonwhite spatial noise 121 6.3 Measurements with narrow noise bands by Stromeyer and Julesz 124 6.4 Measurements with nonwhite noise by van Meeteren and Valeton 127 6.5 Summary and conclusions 129 References 130 7 Contrast discrimination model 131 7.1 Introduction 131 7.2 Evaluation of the psychometric function 132 7.3 Evaluation of the contrast discrimination model 136 7.4 Comparison with contrast discrimination measurements 139 7.5 Generalized contrast discrimination model 143 7.6 Summary and conclusions 147 References 147 8 Image quality measure 149 8.1 Introduction 149 8.2 Nonlinear effect of modulation 150 8.3 Image quality metrics 154 8.3.1 Modulation transfer area (MTFA) 155 8.3.2 Integrated contrast sensitivity (ICS) 155 8.3.3 Subjective quality factor (SQF) 156 8.3.4 Discriminable difference diagram (DDD) 156 8.3.5 Square-root integral (SQRI) 157 8.4 Two-dimensional aspects 158 8.5 Functional analysis of image quality metrics 159 8.6 Effect of differently shaped MTFs 165 8.7 Summary and conclusions 169 References 169 9 Effect of various parameters on image quality 171 9.1 Introduction 171 9.2 Resolution and image size 172 9.3 Luminance and image size 174 9.4 Anisotropic resolution 176 9.5 Viewing distance, display size, and number of scan lines size 177 9.6 Contrast 179 9.7 Gamma 181 9.8 Noise 185 9.9 Pixel density and luminance quantization 190 9.10 Summary and conclusions 193 References 194 10 Epilogue 197 Summary 199 Samenvatting 203 Acknowledgement 207 Curriculum Vitae 209