Announcements http://cseweb.ucsd.edu/classes/sp15/cse152-a/ Piazza - PDF document

Announcements http://cseweb.ucsd.edu/classes/sp15/cse152-a/ • Piazza • Instructor office hours today Human Visual System • Wait list – We’re working to get a larger room. Introduction to Computer Vision – But, if you decide that you’re not going to take CSE 152 the class, please drop it to make room for others. Lecture 3 CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Kepler Ways to study human vision 1. Physiological Kepler, 1604 2. Phenomenological/Psychophysical Eye as an optical 3. Cellular recordings instrument 4. Functional MRI Image is inverted on retina 5. Computational modeling First such experiment by Scheiner, 1625 CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Physiological level Ways to study human vision 1. Physiologically 2. Phenomenological/Psychophysical 3. Cellular recordings 4. Functional MRI 5. Computational modelling CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 1

Example: Psychophysical Testing of Subjects Show gratings w/ different spatial frequencies CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Gradients/Motion Perceptual Organization Look Here Occlusion provides a different organization CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Perceptual Organization Ways to study human vision 1. Physiologically 2. Phenomenological/Psychophysical 3. Cellular recordings 4. Functional MRI 5. Computational modeling CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 2

Single Cell Recordings fMRI Activation in the right fusiform gyrus. [ Tarr, Cheng 2003] CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Ways to study human vision Computational Modeling 1. Physiologically 2. Phenomenological/Psychophysical 3. Cellular recordings 4. Functional MRI 5. Computational modeling What is being computed and why? CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Structure of the eye 1 lux = 1 lumin/m 2 CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 3

Rods and cones Distribution of Rods & Cones Cones CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Retina edge on Three types of cones: R,G,B   k (  ) E (  ) d  Response of k’th cone = There are three types of cones S: Short wave lengths (Blue) • Three attributes to a color M: Mid wave lengths (Green) • Three numbers to describe a color L: Long wave lengths (Red) CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Retinal Neuron Bipolar Cell Ganglion Other Eyes CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 4

Trilobite Visual System Scallop eyes • Hundreds of primitives eyes, mirror in back • Most ancient known visual system. • Changes in light and motion and very rough images are registered on the retinas of the mollusk. • Compound eye with single crystal for each • Nice material at: http://soma.npa.uiuc.edu/courses/bio303/Ch11b.html lens. Electron Micrograph of Holochroal eye Good trilobite eye info at: http://www.aloha.net/~smgon/eyes.htm CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Stomatopod eyes Mantis Shrimp • Dumb bell shaped, compound eyes (next slide) • 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 stomatopods • can see ultra-violet and infra-red light • some can see polarized light. • See http://www.ucmp.berkeley.edu/aquarius/ Trinocular vision Larva Mantis Shrimp Adult Mantis Shrimp CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Visual Pathways Single Cell Recordings CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 5

Where: What: Location & Recognition, Motion, control Object representation CUES CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Fixate at center Shading Cues What color are the dots CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Subjective Contours Which square is darker? Kanizsa’s Triangle CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 6

Global vs. Local information: Which square is darker? Fraser’s Spiral CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Context Context: Whose faces do you see? Who is taller? Who is taller? CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 7

A picture of a man In this shot, what is his facial exprssion? CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision In this shot, what is his facial exprssion? Hidden Human Face Thatcher illusion CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision Additional Pictures Parallel Lines CSE 152, Spring 2015 Introduction to Computer Vision CSE 152, Spring 2015 Introduction to Computer Vision 8

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