Color is a psychological property of our visual experiences when we look at objects and lights, not a physical property of those objects or lights, color is the result of interaction between physical light in the environment and our visual system. To help you understand more about this issue, invite you to consult the lecture content "Color". Hope this is useful references for you. | Color Phillip Otto Runge (1777-1810) What is color? Color is a psychological property of our visual experiences when we look at objects and lights, not a physical property of those objects or lights (S. Palmer, Vision Science: Photons to Phenomenology) Color is the result of interaction between physical light in the environment and our visual system Wassily Kandinsky (1866-1944), Murnau Street with Women, 1908 Electromagnetic spectrum Why do we see light at these wavelengths? Because that’s where the sun radiates electromagnetic energy Human Luminance Sensitivity Function The Physics of Light Any source of light can be completely described physically by its spectrum: the amount of energy emitted (per time unit) at each wavelength 400 - 700 nm. © Stephen E. Palmer, 2002 Relative spectral power The Physics of Light Some examples of the spectra of light sources © Stephen E. Palmer, 2002 Rel. power Rel. power Rel. power Rel. power The Physics of Light Some examples of the reflectance spectra of surfaces Wavelength (nm) % Light Reflected Red 400 700 Yellow 400 700 Blue 400 700 Purple 400 700 © Stephen E. Palmer, 2002 Interaction of light and surfaces Reflected color is the result of interaction of light source spectrum with surface reflectance Spectral radiometry All definitions and units are now “per unit wavelength” All terms are now “spectral” Interaction of light and surfaces What is the observed color of any surface under monochromatic light? Olafur Eliasson, Room for one color The Eye The human eye is a camera! Iris - colored annulus with radial muscles Pupil - the hole (aperture) whose size is controlled by the iris Lens - changes shape by using ciliary muscles (to focus on objects at different distances) Retina - photoreceptor cells Slide by Steve Seitz Density of rods and cones Rods and cones are non-uniformly distributed on the retina Rods responsible for intensity, cones responsible for color Fovea - Small region (1 or . | Color Phillip Otto Runge (1777-1810) What is color? Color is a psychological property of our visual experiences when we look at objects and lights, not a physical property of those objects or lights (S. Palmer, Vision Science: Photons to Phenomenology) Color is the result of interaction between physical light in the environment and our visual system Wassily Kandinsky (1866-1944), Murnau Street with Women, 1908 Electromagnetic spectrum Why do we see light at these wavelengths? Because that’s where the sun radiates electromagnetic energy Human Luminance Sensitivity Function The Physics of Light Any source of light can be completely described physically by its spectrum: the amount of energy emitted (per time unit) at each wavelength 400 - 700 nm. © Stephen E. Palmer, 2002 Relative spectral power The Physics of Light Some examples of the spectra of light sources © Stephen E. Palmer, 2002 Rel. power Rel. power Rel. power Rel. power The Physics of Light Some examples .
