Human Visual System

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Human Visual System by 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

1.4.1.1. ∆I/I = K; sensor noise(dark current)

1.4.2. Fechner's Law

1.4.2.1. S = k log(I)

1.4.3. Ricco's Law

1.4.3.1. Log(L) = K-nlog(A), Spatial summation: The trade-off between spatial resolution and sensitivity

1.4.4. Bloch's Law

1.4.4.1. 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

1.6.5.1. β=ordinate of SN / ... N

1.6.5.2. 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

2.1.1.1. Canal of Schlemm, Petinate ligament & trabecular mesh-work

2.1.1.2. Corneal epithelium, transparent cornea, Opaque sclers

2.1.1.3. Descemet's membrace, (Aqueous humor circulating in direction of arrows)

2.1.1.4. Dilator pupil, Sphincter pupillae, Choroidal layer of iris, Double layer of pigment epithelium

2.1.1.5. Lens epithelium(ectoderm), Lens fibres, "nucleus" of lens, lens capsule to which zonular fibres are attached

2.1.1.6. Basement membrane to which fibres of the zonula are attached, ciliary muscle, circular fibres of ciliary muscle...

2.1.1.7. ..., suspensory ligament of zonula of zinn, margin of vitreous humour

2.1.2. Back Structure

2.1.2.1. Optic nerve and retinal vessels

2.1.2.2. Optic disc(blind spot)

2.1.2.3. Fovea

2.1.2.4. Pigment (epithelium)

2.1.2.5. Retina

2.1.2.6. Sclera

2.1.2.7. Choroid

2.1.3. Important Structure & concepts

2.1.3.1. Optical axis, visual axis(5degree), nasal/temporal side, centre of rotation, posterior pole

2.1.3.2. Iris

2.1.3.3. Posterior chamber

2.1.3.4. Zonules

2.1.3.5. Ciliary body

2.1.3.6. Optic disc

2.1.3.7. Optic nerve

2.1.3.8. Fovea

2.1.3.9. Sclera

2.1.3.10. Choroid

2.1.3.11. Retina

2.1.3.12. Gullstrand-LeGrand Model Eye, (Power of them plus "air")

2.1.3.12.1. Cornea

2.1.3.12.2. Aqueous humour

2.1.3.12.3. Lens

2.1.3.12.4. Vitreous humour

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

2.1.5. Line/Point Spread Function

2.1.5.1. Airy Disc: θ=1.22/d

2.1.5.2. LSF/PSF graph with pupil size

2.1.6. Accomodation

2.1.7. Aberrations

2.1.7.1. Chromatic

2.1.7.1.1. Limit aperture

2.1.7.1.2. Spectral selectivity

2.1.7.2. Spherical

2.1.7.2.1. Limit aperture

2.1.7.2.2. Aspherical shape

2.1.7.2.3. Gradient index

2.1.7.3. Astigmatism

2.1.7.3.1. Prism correction

2.1.7.4. Spectacle correction

2.1.7.4.1. Emmetropia

2.1.7.4.2. Myopia

2.1.7.4.3. Hyperopia

2.1.7.5. Presbyopia

2.1.7.6. S+[C*A] (Spectacle prescription)

2.1.7.6.1. S: spherical power to correct for myopia or hyperopia

2.1.7.6.2. C: Cylindrical power to correct for astigmatism

2.1.7.6.3. A: Axis of cylindrical correction

2.2. Photoreceptors

2.2.1. Structure(250um)

2.2.1.1. Pigmented cell

2.2.1.2. Rod(120million)

2.2.1.3. Cone(7million)

2.2.1.4. Horizontal cell

2.2.1.5. Amacrine cell

2.2.1.6. Bipolar cell

2.2.2. Rods & Cones (distribution)

2.2.2.1. Cone: Receptor Mosaic: L:M:S = 32:16:1

2.2.2.1.1. estimated spatial acuity: 5arcsec; 50cyc/deg

2.2.3. Spectral sensitivity

2.2.3.1. graph 1

2.2.3.2. 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

2.2.7.1. Ishihara Pseudoisochromatic Plates

2.2.7.2. Farnsworth-Munsell 100-Hue test

2.2.8. Color Matching

2.2.8.1. Trichromacy vs. Opponent

2.3. Rental Processing

2.3.1. Receptive Field

2.3.1.1. Top-view

2.3.1.2. Lateral-view [inhibitory, excitatory]

2.3.1.3. [Border Illusion example]

2.3.2. Receptive fields in the Retina

2.3.2.1. Structure

2.3.2.1.1. Rod

2.3.2.1.2. Cone

2.3.2.1.3. Bipolar cell (midget/diffuse)

2.3.2.1.4. Ganglion cell (midget/parasol) - to optic nerve

2.3.2.1.5. Vertical pathway/Lateral pathway

2.4. Cortical Processing

2.4.1. Receptive fields beyond the retina

2.4.1.1. Structure

2.4.1.1.1. Optic nerve

2.4.1.1.2. Optic chiasm

2.4.1.1.3. Optic tract

2.4.1.1.4. Lateral Geniculate Nucleus(LGN) [cells are monocular]

2.4.1.1.5. Optic radiation

2.4.1.1.6. Primary visual cortex(V1)

2.4.1.2. Segregate by right/left eye; visual field

2.4.2. Receptive fields beyond LGN

2.4.2.1. Diagram

2.4.2.2. Tuning curves

2.4.2.2.1. Cone

2.4.2.2.2. Simple Cells

2.4.2.2.3. Complex Cells[position(phase) insensitive]

2.4.2.3. Model

2.4.2.3.1. Single Channel

2.4.2.3.2. Multi-resolution Model

2.4.2.4. Oblique Effect : oblique stimuli not so effective as hori/vert

2.4.2.5. Temporal effects: high temp-freq, low CSF

3. Vision and Perception

3.1. Spatial Vision

3.1.1. MTF

3.1.1.1. Modulation = (max-min)/(max+min)

3.1.1.2. MTF = Mod out / Mod in

3.1.2. Contrast Sensitivity Function

3.1.2.1. CSF vs MTF

3.1.3. Fovea

3.1.4. Visual Acuity: Foveal cone spacing ~ 120 samp/deg

3.1.4.1. Snellen acuity: 1 arcmin

3.1.4.2. Grating acuity: 60 cyc/deg

3.1.4.3. 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

3.2.1.1. Space-time-oriented receptive field

3.2.1.2. A method for creating a space-time-oriented receptive field

3.2.1.3. Apparent motion ("fool" HVS)

3.2.1.4. 24 frames/sec sufficient but flicker

3.2.1.5. Aperture problem

3.2.1.5.1. Barber-pole effect

3.2.1.6. Akinetopsia: no perception of motion

3.2.1.7. Untitled

3.2.1.7.1. First order motion: change of luminance

3.2.1.7.2. Second order motion: change in contrast or texture

3.3. Eye movements

3.3.1. Compromise

3.3.1.1. Limited neural resources / bandwidth

3.3.1.2. compromise between field-of-view and acuity

3.3.1.2.1. critical to the surival of prey/predator respectively

3.3.1.3. rods: wide FOV, scotopic sensitivity, cones...

3.3.2. Six muscles

3.3.2.1. Superior/inferior oblique

3.3.2.2. Superior/inferior rectus

3.3.2.3. Lateral/Medial rectus

3.3.3. Eye movement system

3.3.3.1. Image destabilization

3.3.3.1.1. Saccadic eye movements: shifting gaze

3.3.3.2. Image Stabilization

3.3.3.2.1. Object in motion

3.3.3.2.2. Observer in motion

3.3.3.2.3. Large field in motion

3.3.3.2.4. Object in motion (depth)

3.3.3.3. Minature eye movements: tremor/drift/microsaccades

3.3.4. serial execution, spatial and temporal integration

3.4. Depth Perception

3.4.1. Depth Information

3.4.1.1. Oculomotor('ocular')

3.4.1.1.1. Accomodation (intraocular) [ABSOLUTE]

3.4.1.1.2. Convergence (extraocular) [ABSOLUTE]

3.4.1.2. Visual('optical')

3.4.1.2.1. Monocular

3.4.1.2.2. Binocular disparity

3.4.2. Binacular disparity

3.4.2.1. Panum's fusional zone

3.4.2.1.1. Panum's fusional zone

3.4.2.1.2. Horopterline

3.4.2.1.3. diplopia / stereoscopic viewing

3.4.2.2. Vieth-Muller circle

3.5. Color vision

3.5.1. Cone mosaic

3.5.2. Specifying colors

3.5.2.1. Source

3.5.2.2. Object

3.5.2.3. Ocular Media

3.5.2.3.1. aqueous humor transmittance

3.5.2.4. Cone Responses

3.5.2.4.1. S--M-L

3.5.2.4.2. int_380^780 source(wavelength) * object(wl) * T_oc-media(wl) * S(or M, L) (wl) d(wl) = S(or M, L)

3.5.2.5. Opponent Processing

3.5.2.6. Perception

3.5.3. Color matching

3.5.3.1. tristimulus value(z,y,x-bar)

3.5.3.1.1. 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

3.5.6.1. Trichromacy: S,M,L

3.5.6.2. Opponent color hue cancellation : R/G, Y/B, (B/W)

3.5.6.2.1. Unique B/G/Y/ (~R): 475 / 500 / 580 nm

3.5.7. Color Reproduction

3.5.7.1. Additive (RGB)

3.5.7.1.1. Superposition, spatial(partitive) mixing(TV), temporal mixing(DLP)

3.5.7.2. Subtract (CMY[K]) Color Mixing

3.5.8. Color images

3.5.8.1. 24-bit RGB

3.5.8.2. Indexed color images

3.5.8.3. Color compression

3.5.8.3.1. separation into 3 channels, subtraction or Lab

3.5.8.3.2. redundancy

3.5.8.3.3. limitation of HVS: the amount of info carried in RGB channels is similar, but the value of that to the HVS is not

3.5.8.3.4. Lab/n and L(ab/n)

3.5.9. Color blindness: Monochromats, Dichromats, Anomalous Trichromats

3.5.10. The retinex theory

3.5.10.1. Mondrian experiment

3.5.10.2. color constancy: adjust different area to same energy in 3 channels at eye

3.5.10.3. Difference: retinex allowed the extraction of the ratio of LMS signals carrying info about both illuminant & surface

3.5.11. Image display

3.5.11.1. Cathode Ray Tube

3.5.11.2. Flat Panel Displays

3.5.11.2.1. Liquid Crystal

3.5.11.2.2. Plasma Display

3.5.11.2.3. OLED

3.5.11.2.4. eInk

3.5.11.3. Digital Light Processing (DLP)