CSE152, Spring 2007 Intro Computer VisionHuman Visual SystemComputer Vision ICSE 152Lecture 2CSE152, Spring 2007 Intro Computer VisionAnnouncements• Assignment 0: “Getting Started with Matlab”is posted to the web page, due next Thursday. • Matlab will be discussed during discussion section, Wed 9:00 - 9:50 AM in WLH 2208CSE152, Spring 2007 Intro Computer VisionKeplerKepler, 1604Eye as an optical instrumentImage is inverted on retinaFirst such experiment by Scheiner, 1625CSE152, Spring 2007 Intro Computer VisionWays to study human vision1. Physiologically2. Phenomenological/Psychophysical3. Cellular recordings4. Functional MRI5. Computational modellingCSE152, Spring 2007 Intro Computer VisionPhysiological levelCSE152, Spring 2007 Intro Computer VisionWhat does this do?Can we readily understand whole from understanding pieces?CSE152, Spring 2007 Intro Computer VisionWays to study human vision1. Physiologically2. Phenomenological/Psychophysical3. Cellular recordings4. Functional MRI5. Computational modellingCSE152, Spring 2007 Intro Computer VisionPsychophysical Testing of SubjectsCSE152, Spring 2007 Intro Computer VisionExample: Show gratings w/ different spatial frequenciesCSE152, Spring 2007 Intro Computer VisionGradients/MotionLook HereCSE152, Spring 2007 Intro Computer VisionPerceptual OrganizationOcclusion provides a different organizationCSE152, Spring 2007 Intro Computer VisionPerceptual OrganizationCSE152, Spring 2007 Intro Computer VisionWays to study human vision1. Physiologically2. Phenomenological/Psychophysical3. Cellular recordings4. Functional MRI5. Computational modelingCSE152, Spring 2007 Intro Computer VisionSingle Cell RecordingsCSE152, Spring 2007 Intro Computer VisionfMRIActivation in the right fusiform gyrus.[ Tarr, Cheng 2003]CSE152, Spring 2007 Intro Computer VisionWays to study human vision1. Physiologically2. Phenomenological/Psychophysical3. Cellular recordings4. Functional MRI5. Computational modelingCSE152, Spring 2007 Intro Computer VisionComputational ModelingWhat is being computed and why?CSE152, Spring 2007 Intro Computer VisionStructure of the eyeCSE152, Spring 2007 Intro Computer VisionCSE152, Spring 2007 Intro Computer VisionRods and conesConesCSE152, Spring 2007 Intro Computer VisionRods & ConesCSE152, Spring 2007 Intro Computer VisionThree types of cones: R,G,BThere are three types of conesS: Short wave lengths (Blue)M: Mid wave lengths (Green)L: Long wave lengths (Red)• Three attributes to a color• Three numbers to describe a color Response of k’th cone =λλλρdEk)()(∫CSE152, Spring 2007 Intro Computer VisionDistribution of Rods & ConesCSE152, Spring 2007 Intro Computer VisionRetina edge onCSE152, Spring 2007 Intro Computer VisionRetinal NeuronCSE152, Spring 2007 Intro Computer VisionOther EyesCSE152, Spring 2007 Intro Computer VisionTrilobite Visual System• Most ancient known visual system. • Compound eye with single crystal for each lens.Electron Micrograph of Holochroal eyeGood trilobite eye info at: http://www.aloha.net/~smgon/eyes.htmCSE152, Spring 2007 Intro Computer VisionScallop eyes• Hundreds of primitives eyes, mirror in back• Changes in light and motion and very rough images are registered on the retinas of the mollusc.• Nice material at: http://soma.npa.uiuc.edu/courses/bio303/Ch11b.htmlCSE152, Spring 2007 Intro Computer VisionStomatopod eyes • Dumb bell shaped, compound eyes• Stereo vision with just one eye; • Each eye is up on a stalk, with a wide range of motion; • Stomatopods have up to 16 visual pigments stomatopodscan also see ultra-violet and infra-red light, and some can even see polarized light.• See http://www.ucmp.berkeley.edu/aquarius/Larva Mantis ShrimpAdult Mantis ShrimpCSE152, Spring 2007 Intro Computer VisionVisual PathwaysCSE152, Spring 2007 Intro Computer VisionSingle Cell RecordingsCSE152, Spring 2007 Intro Computer VisionCSE152, Spring 2007 Intro Computer VisionCUESCSE152, Spring 2007 Intro Computer VisionShading CuesCSE152, Spring 2007 Intro Computer VisionWhich square is darker?CSE152, Spring 2007 Intro Computer VisionContextWho is taller? Which man is taller?CSE152, Spring 2007 Intro Computer VisionContext: Whose faces do you see?CSE152, Spring 2007 Intro Computer VisionSubjective ContoursKanizsa’s TriangleCSE152, Spring 2007 Intro Computer VisionFraser’s SpiralCSE152, Spring 2007 Intro Computer VisionCSE152, Spring 2007 Intro Computer VisionFixate at center What color are the dotsCSE152, Spring 2007 Intro Computer VisionCSE152, Spring 2007 Intro Computer VisionA picture of a manCSE152, Spring 2007 Intro Computer VisionIn this shot, what is his facial expression?CSE152, Spring 2007 Intro Computer VisionIn this shot, what is his facial