このアプリについて
目を横から切った断面で、光線を1本ずつ計算しています。面ごとにスネルの法則（屈折の法則）で曲げ、虹彩（ひとみ）を通った光だけを網膜まで追います。目の寸法と屈折率は、研究で使われる目の模型（Navarro ほか 1985）の値です。近くを見るときの水晶体の形の変化（調節）も、その論文の式で計算しています。
ピント合わせは「網膜のぼけがいちばん小さくなる調節」を、その年齢でできる範囲（Hofstetter 1950 の平均の式）の中で探しています。ひとみの大きさは明るさから Crawford 1936 の式で決めています（明るさの値はおおよその例）。
見る先や明るさを変えると、目はすぐには追いつきません。ピント合わせは約 0.3 秒の遅れのあと、動く量が大きいほど速く動きます（Bharadwaj & Schor 2006 が測った速さの関係）。ひとみは明るくなると約 0.2 秒の遅れのあと 1 秒ほどで縮み、暗くなると 20 秒ほどかけてゆっくり開きます（Mathôt 2018、Gray ほか 2024）。「時間の流れ」のグラフは、そのあいだのぼけ・調節・ひとみ・暗さ慣れの変わり方です。
乱視は、角膜の丸みが向きによって少しちがう目です。ここでは角膜の前の面の丸みを、ある向き（縦・横・斜め）だけ 0.75〜3 D 分きつくして、その向き（強い向き）と直角の向き（弱い向き）に切った断面をそれぞれ光線で計算しています。見え方は、向きによって広さのちがうぼかし（だ円のぼけ）です。乱視用のメガネ（円柱レンズ）は、2つの向きで度をそれぞれ決めています。
暗い所に入ると、目は分の単位でだんだん敏感になります（暗順応）。見える最小の明るさ（しきい値）を、明るい所で働く錐体と暗い所で働く桿体の2つで計算しています。強い光のあとは、錐体が数分で頭打ちになり、7分ごろに桿体へ切りかわって（Patryas ほか 2013 で 約7分）、桿体は 1 分に 0.23 桁ずつ（45歳以上はおそい）敏感になり、30分ほどでいちばん敏感になります。桿体だけで見ているときは、見え方のまん中がぬけます。中心窩には桿体がないためです（直径 1.25°、Curcio ほか 1990）。しきい値は2つの分の和です。いまの光そのものの分は、暗くなると数秒以内に消えます（Baker 1953 の、はじめの速い下がり）。光で分解された色素の分は、色素がもどるまで残ります（錐体の色素: 半分分解される明るさ 20000 td・もどる時定数 2 分、Rushton & Henry 1968）。だから晴れた屋外から夕方へ出ると、1〜2 秒でうす暗く見えはじめ、数分かけて見やすくなります。晴れた屋外から街灯のない夜道へ出て見えはじめるまでの約14分は、Lamb & Pugh（2004）の色素がもどる式で計算した約15分と合います。
暗い所では視力も下がります。明るさと視力の関係は Shlaer（1937）の測定に Larson ほか（1997）があてはめた式で、夕方（1 cd/m²）は明るい所の約6割、街灯のない夜道（0.001 cd/m²）は約6%です。
残像: 色の図をじっと見つめると、網膜の神経細胞（神経節細胞）がその信号に慣れて、見える信号から少しずつ引き算されます（順応）。図を消して白い面を見ると、引き算だけが残り、反対の色の残像が見えます。その時定数は、サルの網膜の神経節細胞で 5〜12 秒ほど（Zaidi ほか 2012）、人が見る残像で 4〜8 秒（Kelly & Martinez-Uriegas 1993）と測られています。ここでは図の色を3種類の錐体（L・M・S）の信号の差にして、順応の時定数 7 秒で計算しています。残像の表を見ているときは、目の断面の拡大鏡の代わりに「網膜の中」のしくみの図（とどく光 → 錐体 → 神経節細胞の引き算 → 見える色）が出ます。数は残像の計算と同じものです（細胞の絵は模式図）。
簡単にしているところ
- 断面の上下の1平面だけで光線を追っています。網膜は半径 12 mm の球としています（実際はやや平たいだ円体）。
- 水晶体の屈折率は一様としています（本物は中心ほど高い）。調節で、形をゆがめる度合い（非球面の係数）は変えていません。10 D をこえる調節は、式をそのままのばした推定です。
- 年齢で変わるのは調節できる幅と、暗さに慣れる速さだけです（水晶体の形・ひとみの大きさの年齢による変化は入れていません）。近視・遠視は目の長さだけを変えています。
- 光の回折、色によるずれ（色収差）、網膜の細胞の細かさは入れていません。「見え方」は、網膜のぼけの広がりを同じ広がりのぼかしにして近似したものです。「ぼやける」は、ぼけの円が 2 分（1/30 度）より大きいときとしています（このアプリの目安）。
- メガネは角膜の 12 mm 手前のうすいレンズとし、度は 0.25 D きざみ。遠く用は遠くがいちばんくっきりする度、近く用は 40 cm を調節の半分の力で見られる度（このアプリの決め方）です。
- 時間の変化: ピント合わせとひとみは、遅れのあと指数関数で近づくとしています。ピント合わせの速さ（時定数）は、測られたピーク速度の式から「動く量 ÷ ピーク速度」で決めています（遅れは遠くへの切りかえで測られた約 0.3 秒を、近くへにも使用）。ひとみの縮む・開く時定数（0.35 秒・6 秒）は、論文に書かれた経過に合うように決めた推定です。年齢によるピント合わせの速さの変化、ピントのわずかなゆれ、近くを見るときにひとみが縮む反応は入れていません。
- 乱視: 角膜の前の面だけを、ある向きで強くしています（水晶体による乱視は入れていません）。光線は強い向きと弱い向きの2つの断面の中だけで追い、見え方のぼけはその2つの広がりを、その向きにそろえただ円のぼかしにしています（2つの断面の外を斜めに進む光線は計算していません）。ピント合わせは、2つのぼけの平均がいちばん小さくなる所をねらうとしています。
- 暗順応: 錐体の頭打ちの高さ（−1.4 log cd/m²）・桿体のいちばん低いしきい値（−4.6）・色素の分解の割合からしきい値の上がりへの換算（強い光のあと約 1.3 log 上）・いまの光の分（錐体は明るさの 1%、桿体は 10%）とそれが消える速さ（時定数 1 秒）・終わりのゆっくりした部分・前の明るさから決める桿体のはじめの高さ・明るくなったときの速さ（数秒）は、測られた値（切りかわり約7分、30分後 −4.4、強い光で約5桁感度が下がる、錐体は 5〜10 分で頭打ち）に合うように決めた推定です。しきい値は 1° の光の点が見えるかどうかの値で、視力表の見え方の明るさは「その場の明るさ（対数で 0.001 cd/m² → 3割、100 cd/m² 以上 → そのまま）× しきい値をどれだけ上回るか」から決めた目安です。視力（Shlaer 1937・Larson ほか 1997。桿体だけのときは 0.16 まで）は、すきま 0.5÷視力 分がやっと分かるぼかしで表しています（推定）。うす暗いときと桿体だけのときは色みのない灰色にしています。色の見え方のくわしい変化は入れていません。錐体の色素の分解はひとみの明るさ（Crawford）での網膜の明るさで計算しています。
- 残像: 順応の時定数 7 秒と、はねかえりの大きさ（順応しきったとき図の 42%。Zaidi ほか 2012 の、はねかえりの反応と最大の反応の比 0.42 から）は推定です。目はまったく動かず、ピントは合っているとしています。L・M・S の3つの錐体の時定数は同じとし、白い面に変えたときの明るさへの合わせ（光受容体のすばやい順応）は一瞬としています。画面の色から錐体の信号へは、sRGB → XYZ → LMS（Hunt–Pointer–Estévez）の標準の式で換算しています。見る人自身の目にも残像が出るので、画面の残像と重なって見えることがあります。
- 視神経は、場所を示すために断面に描いています（実際は中心窩より鼻の側にあります）。
学習用に簡単にしたものです。目の病気や視力の判断、メガネの度を決めることには使えません。目のことは眼科で相談してください。
おもな出どころ
- Navarro R, Santamaría J, Bescós J (1985) Accommodation-dependent model of the human eye with aspherics. Journal of the Optical Society of America A 2(8):1273–1281. doi:10.1364/JOSAA.2.001273（目の寸法・屈折率・調節の式）
- Hofstetter HW (1950) Useful age-amplitude formula. Optometric World 38:42–45（年齢と調節できる幅の平均: 18.5 − 0.30 × 年齢 D）
- Watson AB, Yellott JI (2012) A unified formula for light-adapted pupil size. Journal of Vision 12(10):12（ひとみの大きさの式のまとめ。ここでは その中の Crawford 1936 の式を使用）
- Bharadwaj SR, Schor CM (2006) Dynamic control of ocular disaccommodation: first and second-order dynamics. Vision Research 46(6–7):1019–1037. doi:10.1016/j.visres.2005.06.005（ピント合わせの遅れ 約 300 ms、ピーク速度の式: 近くへ 1.58 × 動く量 ＋ 3.42 D/s、遠くへ 1.4355 × はじめの調節 ＋ 1.13 D/s）
- Metlapally S, Tong JL, Tahir HJ, Schor CM (2016) Potential role for microfluctuations as a temporal directional cue to accommodation. Journal of Vision 16(6):19（反応の遅れ 175–375 ms）
- Mathôt S (2018) Pupillometry: psychology, physiology, and function. Journal of Cognition 1(1):16. doi:10.5334/joc.18（ひとみ: 光をつけて 0.2 秒まで動かず、1.5 秒までに縮む。消すと 10〜30 秒でゆっくり戻る）
- Gray NS ほか (2024) Measuring the pupillary light reflex using portable instruments in applied settings. Vision 8(4):60. doi:10.3390/vision8040060（ひとみの遅れ 200〜300 ms、最小になるのは 800〜1200 ms）
- Patryas L ほか (2013) Assessment of age changes and repeatability for computer-based rod dark adaptation. Graefe's Archive for Clinical and Experimental Ophthalmology 251:1821–1827. doi:10.1007/s00417-013-2324-5（暗順応: 切りかわり 約7分、桿体の速さ 0.23（45歳以上 0.19）・終わり 0.05 log/分、30分後 −4.4 log cd/m²）
- Bakdalieh A ほか (2025) Dark adaptometry as a diagnostic tool in retinal diseases. Journal of Clinical Medicine 14(11):3742. doi:10.3390/jcm14113742（錐体は 5〜10 分で頭打ち、桿体は 40 分ほどまで）
- Hecht S, Haig C, Chase AM (1937) The influence of light adaptation on subsequent dark adaptation of the eye. Journal of General Physiology 20(6):831–850. doi:10.1085/jgp.20.6.831（前の光が弱いと桿体だけ、強いほど桿体の出番がおそい）
- Curcio CA, Sloan KR, Kalina RE, Hendrickson AE (1990) Human photoreceptor topography. Journal of Comparative Neurology 292(4):497–523. doi:10.1002/cne.902920402（中心窩の桿体のない所 直径 1.25°）
- Shlaer S (1937) The relation between visual acuity and illumination. Journal of General Physiology 21(2):165–188. doi:10.1085/jgp.21.2.165（桿体で見るときの視力 0.16 まで）
- Larson GW, Rushmeier H, Piatko C (1997) A visibility matching tone reproduction operator for high dynamic range scenes. IEEE Transactions on Visualization and Computer Graphics 3(4):291–306. doi:10.1109/2945.646233（明るさと視力の式。Shlaer 1937 のデータへのあてはめ）
- Rushton WAH, Henry GH (1968) Bleaching and regeneration of cone pigments in man. Vision Research 8(6):617–631. doi:10.1016/0042-6989(68)90040-0（錐体の色素: 半分分解される明るさ 4.3 log td、もどる時定数 約2分）
- Baker HD (1953) The instantaneous threshold and early dark adaptation. Journal of the Optical Society of America 43(9):798–803. doi:10.1364/JOSA.43.000798（暗くなった直後のしきい値の速い下がり）
- Lamb TD, Pugh EN Jr (2004) Dark adaptation and the retinoid cycle of vision. Progress in Retinal and Eye Research 23(3):307–380. doi:10.1016/j.preteyeres.2004.03.001（桿体の色素がもどる式（ν 0.094/分、Km 0.17）で、晴れのあと夜道で見えるまでを確かめた）
- Zaidi Q, Ennis R, Cao D, Lee B (2012) Neural locus of color afterimages. Current Biology 22(3):220–224. doi:10.1016/j.cub.2011.12.021（残像は網膜で生まれる。神経節細胞の引き算の順応の時定数 4.8〜17.6 秒、ほとんど 5〜12 秒）
- Kelly DH, Martinez-Uriegas E (1993) Measurements of chromatic and achromatic afterimages. Journal of the Optical Society of America A 10(1):29–37. doi:10.1364/josaa.10.000029（残像の濃さは図の濃さに比例、強まるのも消えるのも時定数 4〜8 秒）
- Kovesi P (2010) Fast almost-Gaussian filtering. DICTA 2010（見え方のぼかしの計算のしかた）
- Atchison DA ほか (2005) Shape of the retinal surface in emmetropia and myopia. Investigative Ophthalmology & Visual Science 46(8):2698–2707（網膜の形）
- ISO 8596（ランドルト環による視力表の形）
使っているもの
フォント: Google Fonts（SIL Open Font License）
About this app
The eye is cut in half and each ray of light is calculated one by one. At every surface the ray is bent with Snell’s law (the law of refraction), and only light that passes through the pupil is followed to the retina. The eye’s sizes and refractive indices come from an eye model used in research (Navarro et al. 1985). How the lens changes shape to look at near things (accommodation) also uses that paper’s formulas.
Focusing searches for the accommodation that makes the blur on the retina smallest, within what is possible at that age (the average formula of Hofstetter 1950). Pupil size comes from the light level using Crawford’s 1936 formula (the light levels are rough examples).
When you change where you look or how bright it is, the eye does not catch up at once. Focusing starts after a delay of about 0.3 s and then moves faster for bigger changes (the speed relation measured by Bharadwaj & Schor 2006). The pupil shrinks in about 1 s after a delay of about 0.2 s when it gets bright, and slowly opens over about 20 s when it gets dark (Mathôt 2018; Gray et al. 2024). The “Over time” graph shows how blur, focusing, the pupil and dark adaptation change meanwhile.
Astigmatism means the cornea is curved a little differently in different directions. Here the front of the cornea is made 0.75–3 D more curved in one direction (vertical, horizontal or diagonal), and rays are calculated in two slices: along that “stronger” direction and at right angles to it (the “weaker” direction). What you see uses a blur whose size differs by direction (an oval blur). Glasses for astigmatism (a cylinder lens) get a separate power for each of the two directions.
In the dark, the eye slowly becomes more sensitive over minutes (dark adaptation). The dimmest light you can see (the threshold) is calculated for two kinds of cells: cones, which work in bright light, and rods, which work in dim light. After bright light, the cones level off within a few minutes; around 7 min the rods take over (about 7 min in Patryas et al. 2013), become 0.23 log units more sensitive per minute (slower over age 45), and reach their best after about 30 min. When only rods are seeing, the middle of the view goes missing, because the fovea has no rods (1.25° across; Curcio et al. 1990). The threshold is the sum of two parts. The part caused by the light itself disappears within seconds when it gets dark (the fast initial drop in Baker 1953). The part caused by pigment bleached by the light stays until the pigment recovers (cone pigment: half bleached at 20,000 td, recovery time constant 2 min; Rushton & Henry 1968). So going from sunny outdoors into dusk, you start to see dimly within 1–2 s, and it gets easier over a few minutes. Going from sunny outdoors to an unlit night road, you start to see after about 14 min, which agrees with the about 15 min calculated from the pigment-recovery formula of Lamb & Pugh (2004).
Acuity also drops in dim light. Light level and acuity follow the formula Larson et al. (1997) fitted to Shlaer’s (1937) measurements: at dusk (1 cd/m²) acuity is about 60% of that in bright light, and on an unlit night road (0.001 cd/m²) about 6%.
Afterimages: when you stare at a colored figure, nerve cells in the retina (ganglion cells) get used to its signal, and it is slowly subtracted from what you see (adaptation). When the figure is replaced by a white surface, only the subtraction remains, so you see an afterimage in the opposite colors. Its time constant was measured as about 5–12 s in monkey retinal ganglion cells (Zaidi et al. 2012) and 4–8 s for afterimages people see (Kelly & Martinez-Uriegas 1993). Here the figure’s colors are turned into differences in the signals of the three cone types (L, M, S) and adapted with a 7 s time constant. While the afterimage chart is shown, the magnifier on the eye is replaced by a diagram of the inside of the retina (light in → cones → the ganglion cell’s subtraction → the color seen). Its numbers are the same as the afterimage calculation (the cells are drawn schematically).
What is simplified
- Rays are followed only in one up-and-down slice. The retina is treated as a sphere of radius 12 mm (really a slightly flattened ellipsoid).
- The lens has one refractive index throughout (a real lens is higher in the middle). Accommodation does not change how much the surfaces bend away from a sphere (the asphere constants). Accommodation above 10 D extends the formula as is (an estimate).
- Age changes only how much the eye can focus and how fast it gets used to the dark (age changes in lens shape and pupil size are not included). Near- and farsightedness change only the eye’s length.
- Diffraction, color fringes (chromatic aberration) and the fineness of retinal cells are not included. “What you see” approximates the spread of the blur on the retina with a blur of the same spread. “Blurry” means the blur circle is larger than 2 arcmin (1/30°) (this app’s rough guide).
- Glasses are a thin lens 12 mm in front of the cornea, in 0.25 D steps. “For distance” is the power that makes far things sharpest; “for reading” is the power that lets you see 40 cm with half of your focusing effort (this app’s rule).
- Over time: focusing and the pupil approach their targets exponentially after a delay. The focusing speed (time constant) is “size of change ÷ peak speed” using the measured peak-speed formulas (the about-0.3 s delay was measured when switching to far; it is also used for near). The pupil’s shrinking and opening time constants (0.35 s and 6 s) are estimates chosen to match the time courses described in the papers. Age changes in focusing speed, tiny focusing wobbles, and the pupil shrinking when looking near are not included.
- Astigmatism: only the front of the cornea is made stronger in one direction (astigmatism from the lens is not included). Rays are followed only in the two slices (stronger and weaker), and the blur in “What you see” is an oval blur lined up with those directions (rays traveling outside the two slices are not calculated). Focusing aims for the smallest average of the two blurs.
- Dark adaptation: the cone level-off (−1.4 log cd/m²), the lowest rod threshold (−4.6), the conversion from bleached pigment to threshold rise (about 1.3 log units after bright light), the part from the light itself (1% of the light level for cones, 10% for rods) and how fast it goes away (time constant 1 s), the slow last part, the rods’ starting height set from the earlier light level, and the speed of readjusting to bright light (a few seconds) are estimates chosen to match measured values (switch to rods at about 7 min, −4.4 after 30 min, about 5 log units of sensitivity lost after bright light, cones level off within 5–10 min). The threshold is for seeing a 1° spot of light; how bright the chart looks is a rough guide: “light level (on a log scale, 0.001 cd/m² → 30%, 100 cd/m² or more → full) × how far the light is above the threshold”. Acuity (Shlaer 1937, Larson et al. 1997; at most 0.16 with rods only) is shown as a blur that just lets a gap of 0.5 ÷ acuity arcmin be seen (an estimate). In dim light and with rods only the chart is a neutral gray. Detailed changes in color vision are not included. Cone pigment bleaching uses the retinal illuminance with the pupil size from the light level (Crawford).
- Afterimages: the 7 s time constant and the rebound size (42% of the figure when fully adapted, from the 0.42 ratio of rebound to maximum response in Zaidi et al. 2012) are estimates. The eye is assumed to stay perfectly still and in focus. The three cone types share one time constant, and the quick brightness adjustment of the photoreceptors when switching to white is treated as instant. Screen colors are converted to cone signals with the standard sRGB → XYZ → LMS (Hunt–Pointer–Estévez) formulas. Your own eyes also make afterimages, which may mix with the one on screen.
- The optic nerve is drawn in this slice only to show it (it really lies toward the nose from the fovea).
This is simplified for learning. It cannot be used to judge eye diseases or eyesight, or to choose glasses. Please see an eye doctor about your eyes.
Main sources
- Navarro R, Santamaría J, Bescós J (1985) Accommodation-dependent model of the human eye with aspherics. Journal of the Optical Society of America A 2(8):1273–1281. doi:10.1364/JOSAA.2.001273 (eye sizes, refractive indices, accommodation formulas)
- Hofstetter HW (1950) Useful age-amplitude formula. Optometric World 38:42–45 (average focusing range by age: 18.5 − 0.30 × age D)
- Watson AB, Yellott JI (2012) A unified formula for light-adapted pupil size. Journal of Vision 12(10):12 (a review of pupil-size formulas; this app uses Crawford’s 1936 formula from it)
- Bharadwaj SR, Schor CM (2006) Dynamic control of ocular disaccommodation: first and second-order dynamics. Vision Research 46(6–7):1019–1037. doi:10.1016/j.visres.2005.06.005 (focusing delay about 300 ms; peak-speed formulas: to near 1.58 × change + 3.42 D/s, to far 1.4355 × starting focus + 1.13 D/s)
- Metlapally S, Tong JL, Tahir HJ, Schor CM (2016) Potential role for microfluctuations as a temporal directional cue to accommodation. Journal of Vision 16(6):19 (response delay 175–375 ms)
- Mathôt S (2018) Pupillometry: psychology, physiology, and function. Journal of Cognition 1(1):16. doi:10.5334/joc.18 (pupil: no change for 0.2 s after a light turns on, shrinks by 1.5 s; after it turns off, slowly recovers over 10–30 s)
- Gray NS et al. (2024) Measuring the pupillary light reflex using portable instruments in applied settings. Vision 8(4):60. doi:10.3390/vision8040060 (pupil delay 200–300 ms; smallest at 800–1200 ms)
- Patryas L et al. (2013) Assessment of age changes and repeatability for computer-based rod dark adaptation. Graefe’s Archive for Clinical and Experimental Ophthalmology 251:1821–1827. doi:10.1007/s00417-013-2324-5 (dark adaptation: switch to rods at about 7 min; rod speed 0.23 (0.19 over age 45) and final part 0.05 log units/min; −4.4 log cd/m² after 30 min)
- Bakdalieh A et al. (2025) Dark adaptometry as a diagnostic tool in retinal diseases. Journal of Clinical Medicine 14(11):3742. doi:10.3390/jcm14113742 (cones level off within 5–10 min; rods keep improving up to about 40 min)
- Hecht S, Haig C, Chase AM (1937) The influence of light adaptation on subsequent dark adaptation of the eye. Journal of General Physiology 20(6):831–850. doi:10.1085/jgp.20.6.831 (after dim light only rods adapt; the brighter the earlier light, the later the rods take over)
- Curcio CA, Sloan KR, Kalina RE, Hendrickson AE (1990) Human photoreceptor topography. Journal of Comparative Neurology 292(4):497–523. doi:10.1002/cne.902920402 (the rod-free zone of the fovea is 1.25° across)
- Shlaer S (1937) The relation between visual acuity and illumination. Journal of General Physiology 21(2):165–188. doi:10.1085/jgp.21.2.165 (acuity with rods is at most 0.16)
- Larson GW, Rushmeier H, Piatko C (1997) A visibility matching tone reproduction operator for high dynamic range scenes. IEEE Transactions on Visualization and Computer Graphics 3(4):291–306. doi:10.1109/2945.646233 (formula for acuity vs. light level, fitted to Shlaer 1937)
- Rushton WAH, Henry GH (1968) Bleaching and regeneration of cone pigments in man. Vision Research 8(6):617–631. doi:10.1016/0042-6989(68)90040-0 (cone pigment: half bleached at 4.3 log td, recovery time constant about 2 min)
- Baker HD (1953) The instantaneous threshold and early dark adaptation. Journal of the Optical Society of America 43(9):798–803. doi:10.1364/JOSA.43.000798 (fast drop of the threshold right after it gets dark)
- Lamb TD, Pugh EN Jr (2004) Dark adaptation and the retinoid cycle of vision. Progress in Retinal and Eye Research 23(3):307–380. doi:10.1016/j.preteyeres.2004.03.001 (rod pigment recovery formula (ν 0.094/min, Km 0.17), used to check the time until you see on a night road after sun)
- Zaidi Q, Ennis R, Cao D, Lee B (2012) Neural locus of color afterimages. Current Biology 22(3):220–224. doi:10.1016/j.cub.2011.12.021 (afterimages arise in the retina; ganglion-cell subtractive adaptation time constants 4.8–17.6 s, mostly 5–12 s)
- Kelly DH, Martinez-Uriegas E (1993) Measurements of chromatic and achromatic afterimages. Journal of the Optical Society of America A 10(1):29–37. doi:10.1364/josaa.10.000029 (afterimage contrast is proportional to the figure’s contrast; builds up and fades with a 4–8 s time constant)
- Kovesi P (2010) Fast almost-Gaussian filtering. DICTA 2010 (how the blur in “What you see” is computed)
- Atchison DA et al. (2005) Shape of the retinal surface in emmetropia and myopia. Investigative Ophthalmology & Visual Science 46(8):2698–2707 (shape of the retina)
- ISO 8596 (the Landolt-ring eye chart)
What it uses
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