人眼视觉特性.

1、人眼视觉特性-人眼视紀人艰非正常视弦-人腋错觉Q 口口S一.-Fr*n.'熔：4.'二行 立沁T 亠 / * * A- r >? 人眼视觉感 光细胞(photoreceptoT cells)： 杆状细胞(rod)t单色夜视 锥状细胞(cone)：彩色视就绿(green)Primary Color 基色r .:也 -”空'"忆一 r, '( -V - I -*'二扌二 八f-pg / 亠;貳貳n,y X *r* J (Kt今 HiarorjarCi a 山却卩1 斜3 FcveaInsI_3Ujg f>iacII vhoroiti6屜

2、M81?TWe ofCMiwisRetiraOptic nerveOptic radiationsVisual cortexMaster DiagrWore detsiiled lock hN LGK a ccricxOptic chiasma LdtfrrdI g令rliculdto nucleusc tex or PUfnbored labels nr mor? inrofmatMiPh&iICorrear 4 E*4z aocuiaf Mua (删15 wwj" Pow那 oTin# Bran1ID OpSC-vnmousJTM5 Lens%veiltfl cuius

3、pars -centralis git - T ：*ri&iviiE. aptkitK dabulbul *1*0为4cp timini 診tnulkioi训 Un 氟jeng optUuR' sinExample Image ot VOXEL-MANPrttn ,994 IMDM Un*ver$it/ Hamburg, GermanyIMBi &頫 M 7,ami wt0r：u£ 4烦 /弘corm 狛 Icrios dcxl MAntri toulus gusrtusiImage formation in the Eyenauviri丁*<|nS(i

4、*i*Kn t.1 IDlWib|n|«4 , tpiniiH* hwn V 0 Ibv rtutIErticf W far hem丨RetinaYoj staemenRRuwiU 峠mr«Ml列:lsiiiUtl*fV rW1Ta U» of CQifaa1 llnuwt wiMLight enters the retina on the side containing theoplic nerves and iravcU ihrough all the layer beforereaching the receptors.How light enters th

5、e retina and is transmitted out the optic nerveThis animaied cartocn illustrates how light (while dot) enters the reiina'<>n the side containing the optic nerves and travels through nil of the retinal layers before finally being absorbed by the photopigment s in the outer segments of the r

6、eceptors. A neural signal yellow do() is generated in the receptors which then travels through the neurons of the various retind layers and finally travels out through th?optic nerve： yp(o ihe hurrol geniculfue nucleus.2 A汙二釦严* 4八Electron Micrograph of Human Visual Receptorsh;列期10RefractionWhen look

7、ing at an object that is far away the lens is kind of skinny. What hap pens when looking at a nearby object?When looking at nearby otjecis the lens gees fatter, causing the image of the object to be focused on to the retina in the fovea. Whal would happen if the lens did noi gel fatter ?By the way,

8、the technical term for this change in lens shape is accominodation. We frequently call it focusing.If the lens can nol properly focus light on Lhe retina, the image will fall either behind or in front of lhe retina. Can you guess what would hap pen if the lens is too fat?If you guessed iluit when th

9、e lens is loo fa( that light is focussed in from of the rtlina, you were right.Is there a remedy for kns problems that do not allow light to be propcriy focused on the retina? Sure.Contact lensJMany people wear contact lenses to help image light properly on to ihe retina. Anolher solution is for a p

10、erson lo wear glasses. This places a lens in front of the eye not on the cornea as is the case with contact lenses.A recent solution is to use a laser to reshapc the cornea, this soluLion is jwssible only in some cases.AstigmatismThere are two kinds of asliginalism; I. leniicutnr und 2. corneal.Asli

11、gmatisin occurs when (he surface of the cornea or of the lens is noi perfectly smooth. If, for example, there is a small flat Bpo【on your cornea (he image in a certain direclinn on your retina will nol be in perfeci focus.9If the figure on (he right was consirucied with all (he radial lines of equal

12、 sharpness and contrast u person without astigmaiisin would see all these radial lines as perfeeily sharp and with the same contrasr The diagram on ihe right has been fudged to illustrate how it might Qppear 10 a person withThis condition can be corrected with a corneal contavl tens croUnder km in a

13、 pair of spectacles.12113456A cornea lens.yvmcn «the typemosi ccntart A-wreruse Qoats on a tsarA wn% s li on in© scierd ollteeye And becLc© the 1«<1515 自I昭d z,枷 lud. 5om« of nhich geUoU nbnlTeI如5 is aoplwd to th©it is neidContact Lenseson aCorneal Contact LensA very

14、ihin plastic lens, often flexible (soft lenses) flg£ on a layer of tears t)n the corneal surface of rhe eye. These lenses can be of the permanent variety or dis posable. The p ermanent ,variety need to be properly cleanedLand tared i()n The disposable are often眾worn coiUinuously and the ihrowna

15、way when removed. Note how (he bollom edge of the lens is againsl (he lower eye lid. If lhe wearer lookK down, the lens is pushed up a link. This "trick"' can be used to provide bilocal contact lenses. These lenses have different powers in lhe center than in the pcriphcry. When ihc wea

16、rer looks down lo read lhe lens is moved to a new position to facilitate seeing sharply at nonniil reading distances. If there is an inregularily on lhe cornea (astigmatism) it is aulomalicatly coirecleil by the combination of the tear layer and (he contact lens.A cylinder lens is different than a s

17、pherical lens which is what one normally sees in spectacles. Although a cylindrical componenl iny be built in to that which sppears sp hericaLAs can be seen in the left diagram a cylinder lens has power only an one axis. In the left it is ihe horizontal axis.This lens does not refnid light in (he ve

18、rtical diKction.Qoueqjosqe 虽MmalozSpectral Sensitivity Curves of Rods & Cones400500560Vdeergfn inmft£tWavelength (rm) After BowraK"皐 DenraM, i9605400Dark Adap tationWhen you firsi enEer an extremely bright eBvironiiwnt for exam pie. when emerging from a dark movies hou&e into a ver

19、y bright sunlit :irea ihe man carving rhe dwek would ap pear lake this. But in less ihan aniiiiuie he will a ppearassetn below. In the left phoic ilie contrast is very low. Below die contrasi is nonnak When ligM adapted a scene rntht look like this.p-olis¥1Time in dark (minutes)For approximatel

20、y the first 10 minulcs in the dark, the cones require less light to reach a threshold response than do the rods. Thereafter, the rods require less light. The poini at which the rods become more sensitive is called the rod<onc break.1 憑>2(KI>p；I8TOG V' 4001 i60av-/ Ou I lOOw 300、SOCKFigu

21、re The plKXcmuItipItcr uibs人眼视觉Color vision defects causeproblems in the real worldThe following demonstration isan exampfe of how the wor/dappears to a person with asevere type of color blindness, deutersnopia.See how you woufd do in a cofor blind wotid2othoroughly cooked?Which meat is the mostJ&qu

22、ot;ZjWhich meat is the mostthoroughly cooked?*忑0 *icn flask contains 合 TlTpink soluHdnPoink solution?” BA.就眄匸El遢昆MHWWhich of the toltowrng slides contains a pink cell?Which of thg following slides contains a pink cell?Which picture contains a red crayon?!V'7-iiTA核1琢a ?Which picture contains a re

23、d crayon?« toVTrichromSlic Vision otchrornatic VisionPtOtUOH -Oobf MiC«*iXyqooKM 童A*爲tnanomsters)In Its most severe forms, color blindness is caused by the absence of one of the cone visual pigments. Shown here, the spectral sensitivities of the cone pigments in color normal trichromats ar

24、e compared with those of a color blind person. Also compare the spectrum as it appears to a color normal person with the illustration of how it might look to a red-green color blind person.Trichromatic visionDichromatic VisionThe difficulties with certain colors can be illustrated on a color wheel.

25、For a severely red-green color blind person there are only two hues, the ones a color normal person sees as yellow and blue. Intermediate colors, the ones seen as blueish green and magenta, appear gray.Clear graphics are very important and often the source of the most difficulty; here are two exampl

26、es showing the difference between good and bad use of color. The Trick is to keep brightness differences large and to avoid cofor combinations that do not contrast well.BadTrichromatic DichromaticVisionVisionr«*rmr)h Mi aiAimw jBluwsh-Reds and Blufiish-OreerksA com parison of the two color whee

27、ls shows which color combi nations would be difficult to see. Grap hies cause the most problems, but the colors can be economically illustrated as text exam pies, below. The right-hand column illustrates how the left hand column might look to a color blind person.Some exam pies of color combinations

28、 that are easily seen by a color blind person are shown below. These are illustrated as lext exam pies but these p rinci pies are most important to keep in mind when preparing drawings, graphs, and figures.DichromaticVisionTrichromaticVisionm Mff jM iMdQramK tfitun m m jv« ratfjraw A Mi oAjmn &

29、#187; tfJty n9M “03 to »lohibM jKsoffBlues and yellowscontrast well.Blues and yellowscontrast well.Keep brightnessdifferences large.Keep brightnessdHTer«flces large.TrichromaticVisionDichromaticVisionHues that are not seen n colored ar« O< K with large brightness differencesW fnf j

30、Hitf iijLJhvrmvMh 血 ow> iM M fMFMW fl DiK CMmn JK 0*iy 血期xv te J eoMftiM jmanHu« tMc are not seen "GOtored are d K with large brightne$, dlfTerencesBOLD. Avoid nne detaiLBOLD. Avo d nne deta LB ues and Vo owt ilsacontnst wtf wrih b uish-Bluas and taIIows also16 ntrafit w« w»h

31、b ulfi h-grMnt and m 旳nugrMfu AndKeep text Faroe andKeep text large andTxnnomacyDcwonty MorxhramicyNormil TrtchrotfnalAnomeKHj* rrlcrr-ontatDichroniaty COS&0£<COKS3<4«Wav«t»Mlh*l<*mt-1- r*- T -!(iiml.*拘是色盲？7片L'眼见为卖？形"W 二；：" .7",% Z 斗 律鸟 -A彖： *-r叮&#

32、39;"-;S t.xy'Z L x玄 "W V E "£?&八;匚曲匸'弋 * q七仔叮*宀马絲帶效应 '亍定* *&："八 V T%审严7 :-U八"辭;'叮'"Delance Rom let edgeColor Influences Distance Perceptiontne$g|0ter? ns ai 卩 mnsQ on 斤 w vhcd mntDr,:ncy «水 倆ty ate / incariQUinirc same plane, anx ai

33、lneZs4)|ear:aCe 汕 the sane psneoTQo some oear oowr ore re?mof# nf-TanmonnftRadiating LinesClicx anynhcTj on On figure to ina ajtwh<Color Assimilation Take two pieces cf paper and place heir edges as close as possible fo fx>ih sides of one red iliugonal. Note ihiii ihc rcd square in ihc middle

34、is ihc same its all iIk wihcr 凶luuxs on that diagonal. Now(nove your pleces of puper to exposetbc red squares; on theother diagonal. On this diufonul all ihe red squares. incEudinj ilie center on© arc a-ain the same color fed- Recau&e the center 凶uare 祜 cciumon to both dionals this exercise

35、 proves thai all the red squares in tx)ih dugongs are exacily ihe same red color Yei. when Lhc jxHiEcm is seen as a whole, the iwo red diagonatx ;ippc;汕 difTcrcni from each oihcrHermann Grid Illusion-IA 击 n片 *MFLASHHering & Pogendorf IllusionsFun ThrnsaHering ItlusionHHPoggendorfT IllusionHorizo

36、ntal-Vertical IllusionWhich line is longer lhe red one or the green one? Use a ruler to find out. You wil probably be surprised.Mueller-Lyer Illusion*"Stabili2ation'* Causes Fading、Look at the upper right figure.Thii expcrimcni works better if you cloee One eye. Fixate on the black dot in t

37、he corner for about 10 - 15 seconds- Pay ckise attention E(> whai you see. Now do the same thing with the upper left figure.Did you notice any difference? In the accompany ing explanadon I tell you whal most people sec and the reas.t>n for it.Kanizsa IllusionThis is called a Kanizsa figure aft

38、er the person who invented it. If you look carefully you will probably see the edges of (he entire triangle, even though the triangle is defined only by ihc notches in ihc red disks.Which is longer the red line or the blue line? Use n ruler to find out (he answer. Select ihe answer lo double check o

39、n your result.JOIN.xi 一A 击 n片 *MFLASHSimultaneous ContrastThe rcurtd dots flte all exactly (he colof gray. 1 merely created the one on the extreme right and then copied il to each of the darker reclangics- Clearly, the lightness of the background effects the way in which we perceive the center gray

40、dot. This effect is called simultaneous contrast- Again as can b seen in other demonsimuons. the perception of this kind of display i$ a rvsuk of luwral interactions.Simultaneous ContrastThe circular area in each quadrant in the left figure is CKacUy the same elor The ditlcrcnl uppciirancc is due lo

41、 ihc surround and the lateral inlcmelionslhuL octun On Ihc right I merely changed Ihc background colors so thuc they arc ail idcnlicak You can now see ihai itic circular areas arc. indeed. idcnlic=aLThis phcncmcnon is called simullaiicous color conlrasl.Necker CubeLook at the green dot Is it toe ated ir the lower left rear or in the lowe