Visual Science: Spatial Vision: Chapter 7

Question 1

1. What limits your VA? (2)

Answer 1

1. Optics of the Eye and Photoreceptor Mosaic and Neural Processing

Question 2

1. What 2 things about the Optics of the Eye will limit VA?

Answer 2

1. Monochromatic and Polychromatic Aberrations

Question 3

Image Blur

1. 3 Sources of Image blur?

Answer 3

1. Scatter
2. Diffraction
3. Aberrations

Question 4

How do we study the exceedingly Complex Processes of Spatial Vision?

1. The Transition from bright to dark bars is what?
2. Sine Wave Grating: 4 things to consider

Answer 4

1. It’s a Gradual (Sinusoidal) Transition
2. a. Contrast
   b. Frequency
   c. Phase
   d. Orientation of Space

Question 5

Period/Cycle

1. What is the Period or Cycle?
2. Spatial Frequency = ?

Answer 5

1. Size in Degrees

2. 1/period in Cycles/Degree

Question 6

Frequency of a Grating

1. Low spatial Frequency would be considered what?
2. High Spatial Frequency?

Answer 6

1. 2.5 cycles/degree

2. 20 cycles/degree

Question 7

Phase of a Grating

1. What does phase refer to?
2. If two gratings are IN PHASE, what does this mean?
3. If 2 gratings are 180 degrees Out-of-Phase, what does this mean?

Answer 7

1. The position of a Sine wave grating w/respect to another sine wave grating
2. The PEAKS and TROUGHS of their LUMINANCE profiles will be in Alignment
3. If 2 gratings are 180 degrees out-of phase, the Peak of one Luminance profile will be aligned with the trough of the other profile

Question 8

Contrast of a Grating

1. Contrast = ?
2. Average Luminance (Lave) is what?
   a. The bottom one has what? Which is indicative of what?
3. Change of l: is what?
4. LAve is what?

Answer 8

1. Change of l / Iave
2. is the SAME for BOTH the GRATINGS.
   a. Bottom one has a LARGER DIFFERENCE b/w its peak and the average luminance value. This is indicative of higher contrast
3. The Difference b/w the Peak and Average Luminances.
4. Average Luminance of the Grating (the average of the light peaks and dark troughs)

Question 9

Gratings: Michelson Contrast

1. C = ?

Answer 9

1. (Lmax - Lmin)/(Lmax + Lmin)

Question 10

Fourier Analysis

1. Sine waves of what 4 things can be USED to CONSTRUCT what?

Answer 10

1. Proper frequency, contrast, phase, and orientation.

* Construct more Complex Spatial Stimuli