Human Visual System

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Human Visual System により Mind Map: Human Visual System

1. Psychophysics

1.1. Hierarchy of Scales: Nominal, Ordinal, Interval, Ratio

1.2. Absolute/Difference threshold; Sensitivity=1/threshold

1.3. Dark adaption curve

1.4. Four Laws

1.4.1. Weber's Law ∆I/I = K; sensor noise(dark current)

1.4.2. Fechner's Law S = k log(I)

1.4.3. Ricco's Law Log(L) = K-nlog(A), Spatial summation: The trade-off between spatial resolution and sensitivity

1.4.4. Bloch's Law Log(L) = K-nlog(t), Temporal summation: The trade-off between temporal resolution and sensitivity

1.5. Classical Psychophysical Methods

1.5.1. Adjustment

1.5.2. Limits

1.5.3. Constant Stimuli

1.5.4. (Multiple) Staircase (abbreviated limits)

1.5.5. Quest

1.5.6. Forced choice

1.6. The Theory of Signal Detection

1.6.1. Probability, Noise, Signal + Noise, criterion response

1.6.2. hit, miss, false alarm, correct rejection

1.6.3. ROC and d', criterion

1.6.4. d' = Z(hit) - Z(fa) = Z_N - Z_SN

1.6.5. Observer Criterion β=ordinate of SN / ... N β_opt = p(N)/P(SN) *[ (val(cj) - cost(fa)) / (val(hit)-cost(miss)) ], cost is negative

2. Visual Processing

2.1. Eye & Visual Optics

2.1.1. Front Structure Canal of Schlemm, Petinate ligament & trabecular mesh-work Corneal epithelium, transparent cornea, Opaque sclers Descemet's membrace, (Aqueous humor circulating in direction of arrows) Dilator pupil, Sphincter pupillae, Choroidal layer of iris, Double layer of pigment epithelium Lens epithelium(ectoderm), Lens fibres, "nucleus" of lens, lens capsule to which zonular fibres are attached Basement membrane to which fibres of the zonula are attached, ciliary muscle, circular fibres of ciliary muscle... ..., suspensory ligament of zonula of zinn, margin of vitreous humour

2.1.2. Back Structure Optic nerve and retinal vessels Optic disc(blind spot) Fovea Pigment (epithelium) Retina Sclera Choroid

2.1.3. Important Structure & concepts Optical axis, visual axis(5degree), nasal/temporal side, centre of rotation, posterior pole Iris Posterior chamber Zonules Ciliary body Optic disc Optic nerve Fovea Sclera Choroid Retina Gullstrand-LeGrand Model Eye, (Power of them plus "air") Cornea Aqueous humour Lens Vitreous humour

2.1.4. Refractive Power P=(n'-n)/R

2.1.5. Line/Point Spread Function Airy Disc: θ=1.22/d LSF/PSF graph with pupil size

2.1.6. Accomodation

2.1.7. Aberrations Chromatic Limit aperture Spectral selectivity Spherical Limit aperture Aspherical shape Gradient index Astigmatism Prism correction Spectacle correction Emmetropia Myopia Hyperopia Presbyopia S+[C*A] (Spectacle prescription) S: spherical power to correct for myopia or hyperopia C: Cylindrical power to correct for astigmatism A: Axis of cylindrical correction

2.2. Photoreceptors

2.2.1. Structure(250um) Pigmented cell Rod(120million) Cone(7million) Horizontal cell Amacrine cell Bipolar cell

2.2.2. Rods & Cones (distribution) Cone: Receptor Mosaic: L:M:S = 32:16:1 estimated spatial acuity: 5arcsec; 50cyc/deg

2.2.3. Spectral sensitivity graph 1 graph 2

2.2.4. Ganglion cell(1million, 127:1, but in fovea 1:3)

2.2.5. Rhodopsin

2.2.6. Graded potential vs action potential

2.2.7. Color Vision Screening Ishihara Pseudoisochromatic Plates Farnsworth-Munsell 100-Hue test

2.2.8. Color Matching Trichromacy vs. Opponent

2.3. Rental Processing

2.3.1. Receptive Field Top-view Lateral-view [inhibitory, excitatory] [Border Illusion example]

2.3.2. Receptive fields in the Retina Structure Rod Cone Bipolar cell (midget/diffuse) Ganglion cell (midget/parasol) - to optic nerve Vertical pathway/Lateral pathway

2.4. Cortical Processing

2.4.1. Receptive fields beyond the retina Structure Optic nerve Optic chiasm Optic tract Lateral Geniculate Nucleus(LGN) [cells are monocular] Optic radiation Primary visual cortex(V1) Segregate by right/left eye; visual field

2.4.2. Receptive fields beyond LGN Diagram Tuning curves Cone Simple Cells Complex Cells[position(phase) insensitive] Model Single Channel Multi-resolution Model Oblique Effect : oblique stimuli not so effective as hori/vert Temporal effects: high temp-freq, low CSF

3. Vision and Perception

3.1. Spatial Vision

3.1.1. MTF Modulation = (max-min)/(max+min) MTF = Mod out / Mod in

3.1.2. Contrast Sensitivity Function CSF vs MTF

3.1.3. Fovea

3.1.4. Visual Acuity: Foveal cone spacing ~ 120 samp/deg Snellen acuity: 1 arcmin Grating acuity: 60 cyc/deg Vernier acuity (hyperacuity): ~5 arcsec (6X)

3.1.5. CSF: with temporal/spatial/color

3.2. Temporal vision and motion

3.2.1. Motion Perception Space-time-oriented receptive field A method for creating a space-time-oriented receptive field Apparent motion ("fool" HVS) 24 frames/sec sufficient but flicker Aperture problem Barber-pole effect Akinetopsia: no perception of motion Untitled First order motion: change of luminance Second order motion: change in contrast or texture

3.3. Eye movements

3.3.1. Compromise Limited neural resources / bandwidth compromise between field-of-view and acuity critical to the surival of prey/predator respectively rods: wide FOV, scotopic sensitivity, cones...

3.3.2. Six muscles Superior/inferior oblique Superior/inferior rectus Lateral/Medial rectus

3.3.3. Eye movement system Image destabilization Saccadic eye movements: shifting gaze Image Stabilization Object in motion Observer in motion Large field in motion Object in motion (depth) Minature eye movements: tremor/drift/microsaccades

3.3.4. serial execution, spatial and temporal integration

3.4. Depth Perception

3.4.1. Depth Information Oculomotor('ocular') Accomodation (intraocular) [ABSOLUTE] Convergence (extraocular) [ABSOLUTE] Visual('optical') Monocular Binocular disparity

3.4.2. Binacular disparity Panum's fusional zone Panum's fusional zone Horopterline diplopia / stereoscopic viewing Vieth-Muller circle

3.5. Color vision

3.5.1. Cone mosaic

3.5.2. Specifying colors Source Object Ocular Media aqueous humor transmittance Cone Responses S--M-L int_380^780 source(wavelength) * object(wl) * T_oc-media(wl) * S(or M, L) (wl) d(wl) = S(or M, L) Opponent Processing Perception

3.5.3. Color matching tristimulus value(z,y,x-bar) Color signal(Src*Obj) -> CIE color matching functions -> tristimulus values -> chromaticity coordinates

3.5.4. x,y Chromaticity diagram

3.5.5. CIE Lab: L a b from tristimulus values and them in reference white

3.5.6. Trichromacy vs. Opponent Trichromacy: S,M,L Opponent color hue cancellation : R/G, Y/B, (B/W) Unique B/G/Y/ (~R): 475 / 500 / 580 nm

3.5.7. Color Reproduction Additive (RGB) Superposition, spatial(partitive) mixing(TV), temporal mixing(DLP) Subtract (CMY[K]) Color Mixing

3.5.8. Color images 24-bit RGB Indexed color images Color compression separation into 3 channels, subtraction or Lab redundancy limitation of HVS: the amount of info carried in RGB channels is similar, but the value of that to the HVS is not Lab/n and L(ab/n)

3.5.9. Color blindness: Monochromats, Dichromats, Anomalous Trichromats

3.5.10. The retinex theory Mondrian experiment color constancy: adjust different area to same energy in 3 channels at eye Difference: retinex allowed the extraction of the ratio of LMS signals carrying info about both illuminant & surface

3.5.11. Image display Cathode Ray Tube Flat Panel Displays Liquid Crystal Plasma Display OLED eInk Digital Light Processing (DLP)