-
Visible Energy
- What we percieve as light is narrow band of electromagnetic energy. (380 nonmeters to 760nm).
- Only wavelengths in this range stimulate receptors in the eye that permit vision.
-
Spectral color
a light of a specific wavelength exhibiting deep chromatic saturation
-
Hue
the attribute of color perception (i.e. red, organe, yellow, green, blue, violet)
-
Lens
throws a minute inverted image onto a dense mosaic of light sensitive receptors, which convert the patterns of light energy into chains of electrical impulses that the brain will interpret.
-
Pinhole
the hole must be small (allowing little light to pass through) if the image is to be sharp.
-
Lens Issues
- 1) lens focuses the image in front or behind the retina instead of on it, short sighted (nearsighted or myopic) or long sighted (farsighted or hyperopic)
- 2) lens is not truly spherical, giving distortion and, in some directions, blurring of the image (astigmatic)
- 3) the cornea is irregular or pitted
-
Corneal Lenses
fitted to the eye itself serve to give fresh surfae to cornea unlike regular eyeglasses
-
Iris
pigmented part of the eye; color has no impact on vision as long as it is opaque.
-
Pupil
Iris is a muscle that forms the pupil; light passes through the pupil to the lens which lies immediately behind it.
-
Retina
thin sheet of light-sensitive nerve cells converting light into electrical impulses.
-
Rods and Cones
Light receptor cells named after their appearance under microscope
-
Photopic
color vision, using the cones of the retina
-
Scotopic
the gray world given by the rods in dim light
-
Mesopic
when both rods and cones are active
-
The eyes supply the brain with what?
Information coded into chains of electrical impulses
-
Illusion
when the perception (the hypothesis) of an object is incorrect
-
Luminance
light entering the eye which gives rise to the sensation of brightness
-
Illuminance
the density of light recieved on a surface
-
Brightness is the result of intensities of light:
- 1) intesity of light falling on a given region of the retina at a certain time
- 2)the intensity of light that the retina has been subject to in the recent past (called adaptation)
- 3) the intensities of light falling on other regions of the retina (called contrast)
-
Acuity
the ability of the eye to make out fine detail
-
How do cone and rod receptor cells adapt?
At different rates
-
How do colors in the middle of the spectrum look from the end?
For a given intensity, the colors in the middle of the spectrum look brighter than those at the ends.
-
Purkinje Shift
their shape is similar, but the cones are most sensitive to yellow, and the rods are most sensitive to green.
-
Visible Spectrum is comprised of what?
Five colors of light; violet, blue, green, yellow and red.
-
By mixing three colors of light and adjusting their intensities, any spectral hue can be produced, what else can be produced?
White can be made, but not black or nonspectral colors such as brown.
-
Technically, light itself is not colored:
it gives rise to sensations of brightness and color, but not only in conjunction with a suitable eye and nervous system.
-
What colors of the spectrum are interpreted by the brain from only three kinds of receptors in the eyes?
violet, green, and red
-
Color Constancy
knowledge of the normal color of objects.
|
|
