Optical Illusions continued

other plates shown & discussed:

The Successive Contrast optical illusion -
demonstrating retinal fatigue.

Stare at the blue circles until it's hard to concentrate -
then look at the black dot in the white area to see the red/orange circles

after-image optical-illusion

Simultaneous and Successive Contrast at NASA.gov

Color Context/Simultaneous Contrast by Stuart Grais at DePaul University

Simultaneous Contrast by Greg Clayton at Harding University





Weber-Fechner Law

pigment vs. perception

In layering pigment, the rule of having to increase measured steps disproportionately,
as opposed to incrementally, in order to perceive an incremental change in value.

In other words, in order to perceive a 10% increase in value,
more than 10% additional paint or pigment must be added to the layer.

perceived value in pigment




The Munsell and Ostwald" Color Trees"
3-D color wheels and "color solids"

Munsell Color Wheel in 3-D   Ostwald 3-D Color Tree
used by artists and industry to specify exact colors

Art and Visual Perception: A Psychology of the Creative Eye by Rudolf Arnheim at Google Books

Albert H. Munsell at Munsell Color | Wilhelm Ostwald at Color System


wavelengths for halide lamp

Spectral Energy Distribution is the measurement of the presence of the many
lightwaves in natural light and most man-made light, which represent the
whole color spectrum.

"Monochromatic" filters and lights can be created, which are composed of
rays which do not overlap the entire visible spectrum.

Spectral Energy Distribution at California Institute of Technology



Spectral Transmittance Curve


color filters for industry
These charts refer to specific rays that will be
passed by certain filters

In Nature, as mentioned in Spectral Energy Distribution,
colors other than the perceived color are actually present in the light.

Fresnel Equations at Wikipedia



lecture contents