1 / 42

# Autostereograms - PowerPoint PPT Presentation

Autostereograms. What would happen if you remove the divider of a stereoscope?. Convergence is on a point at the same distance as the images Boxes and faces are on the horopter How many boxes would you see?. boxes and faces are on the horopter. Autostereograms. Now cross your eyes:.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Autostereograms' - pelham

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

What would happen if you remove the divider of a stereoscope?

• Convergence is on a point at the same distance as the images

• Boxes and faces are on the horopter

• How many boxes would you see?

boxes and faces are on the horopter

• right-eye line of sight crosses left-eye line of sight in front of image (crossed convergence)

• each retina is now pointed at the opposite box

• How many boxes would you see?

• What would happen to the face?

crossed convergence

• There would be three boxes

• middle box: right eye sees face shifted to right; left eye sees face shifted to left therefore:

• uncrossed disparity

• Face in the middle box appears behind square

crossed convergence

Crossed convergence shifts right image to the right of the left image and vice versa:

Left Eye’s Image

Right Eye’s Image

What would happen if the convergence was uncrossed?

Uncrossed convergence shifts right-eye’s image to the left of the left-eye image and vice versa:

Left Eye

Right Eye

What would happen if the faces were switched relative to the boxes?

• one doesn’t even need two different images!

RIGHT EYE

LEFT EYE

Faces fuse

Convergence tells your brain that the plane of the image is farther away than it really is

• Uneven spacing between identical objects in a single picture can appear as disparity if the angle of convergence is inappropriate

• Uneven spacing between identical objects in a single picture can appear as disparity if the angle of convergence is inappropriate

• TRICK: Seeing depth in autostereograms requires you to suppress the reflexive coordination between convergence and accommodation

Any repeating objects that have a spacing different from the background will have either crossed or uncrossed disparity

RIGHT EYE

LEFT EYE

If you uncross convergence, your right eye gets these faces shifted slightly to left, left eye gets them shifted to right = CROSSED DISPARITY

What would you see?

Any repeating objects that have a spacing difference from the background will have either crossed or uncrossed disparity

RIGHT EYE

LEFT EYE

If you uncross convergence, right eye gets these faces shifted slightly to right, left eye gets them shifted to left = UNCROSSED DISPARITY

What would you see?

• by adjusting the disparity at different parts of the image (with a computer usually) one can make shapes that emerge or recede in depth

• Usually viewed with uncrossed convergence

• Imagine gazing farther than the surface (let your eyes “relax”)

• Now try to notice objects or forms in the blurriness

• As you become aware of shapes, try to focus (accommodate) the plane of the image without converging your eyes

• Recall that light is electromagnetic radiation

• Recall that light is electromagnetic radiation

• Light waves have a frequency/wavelength

• Recall that light is electromagnetic radiation

• Light waves have a frequency/wavelength

• Frequency/wavelength is the physical property that corresponds (loosely) to the perception called color

Wavelength and Color

• Different wavelengths correspond roughly to the “colors” of the spectrum

Wavelength and Color

• White light is a mixture of wavelengths

• prisms decompose white light into assorted wavelengths

Wavelength and Color

• White light is a mixture of wavelengths

• prisms decompose white light into assorted wavelengths

• likewise, adding all wavelengths together makes white light

What happens if you mix several different paints together?

Wavelength and Color

• Objects have different colors because they reflect some but not all wavelengths of light

• the surfaces of objects are like filters that selectively absorb certain wavelengths

Perceiving Color

• Primary colors

What are the primary colors?

Perceiving Color

• Primary colors

RedGreenBlue

Perceiving Color

• Primary colors

What makes them primary?

Perceiving Color

• Primary colors

• Every color (hue) can be created by blending light of the three primary colors in differing proportions

Perceiving Color

• Primary colors

• Every color (hue) can be created by blending light of the three primary colors in differing proportions

• Led to prediction that there must be three (and only three) distinct color receptor types

Perceiving Color

• Four absorption peaks in retina: 3 cone types plus rods

Absorption/Cone response

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

Blue

“Green”

“Red”

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

“Green”

Green

“Red”

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

“Green”

“Red”

Red

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

Equal Parts Red and Green =

“Green”

Yellow

“Red”

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

Equal Parts Red and Green =

“Green”

Yellow

“Red”

Theories of Color Vision

Signal to Brain

Wavelength Input

Cone

“Blue”

Equal Parts Red and Green =

“Green”

Yellow

“Red”

• Color Vision

• Read Land Article for Thursday Feb 28th

• Go skiing