Vision & Light

1. Vision & Light

2. Vision & PerceptionThe whole point of any display is to deliver clear and comprehensible information to an audience. & Blurry Clear

3. Our Optical System • The light passes through the cornea, a clear covering in front of the eye. • The lens, or iris, is behind the cornea and the pupil in the center. • The pupil is an opening in which the light passes. The iris is what causes the diameter of the pupil change. As the intensity of light decreases, the diameter will become larger and allows more light through. • When the lens focuses the light at the back of the eye, it’s called the retina.

4. There are two types of light receptors that cover the surface of the retina – cones and rods. Cones are receptors used to see under bright conditions. They are placed at the center of the retina. Cones also let us have the ability to sense color and see the fine details in what we see. Rods are very sensitive to low levels of light and do not pick up color. Rods help us see during the night. Most rods are located on the perimeter of the retina, which makes our peripheral vision to be blurry and unsharp. The optical nerve which transmit the visual data to the brain, which are located behind the cones and rods. Our Optical System

5. Visual Field **THE SIZE OF EACH EYE’S VISUAL FIELD IS IMPRESSIVE: 135 HIGH AND 160 WIDE. ALL TOGETHER, THE HORIZONTAL FIELD OF VIEW IS 200**

6. The two theories of light Light, like sound is made of waves of energy. Light is made of small particles, called photons. Light waves- the waves of energy are categorized by their wavelength. Light

7. How fast does light travel The speed of light = 186,000 m / s That's miles per second! Or 700 Million Miles per hour. It takes 1.2 seconds for light to travel from the Moon to the Earth and 8.5 minutes from the Sun to the Earth. Speed of sound = 769 miles per hour

8. Of interest: Proxima Centauri is the nearest star to the sun. If we could travel at the speed of light it would take us 4.22 years to get there. Gliese 581 c is thought to be the closest habitable planet. It's only 20.4 light years away.

9. This is the Electromagnetic Spectrum. The waves of energy are categorized by their wavelength. We can only see a small section of the electromagnetic spectrum, which is the color spectrum, shown in color above.

10. Three Aspects of Light Wavelength: Distinguishes the different types of light. Frequency: Determines the color of the light. Amplitude: Refers to the brightness of a light wave.

11. Wavelengths The distance in meters between two corresponding points of two consecutive cycles. With light, that distance is typically measured in nanometers. A nanometer is equal to one billionth of a meter (10^-9 m).

12. The Sun’s Effects The best explanation of why we see light only in wavelengths of 400-750 nanometers is that these wavelengths are the make up of sunlight through our atmosphere.

13. Frequency Frequency is the number of cycles in a given time period, measured in Hertz (Hz). The frequency of a light wave determines it’s color. 1Hz = 1 cycle/sec

14. Frequency Gamma Rays have a frequency of 10^18 Hz Radio Waves have a frequency of 10^4 Hz

15. Frequency and Colors Green is at the center of the color spectrum. Blue light waves have a higher frequency, which makes it harder to see. Red light waves have a lower frequency. Visible light with a frequency of about 10^14 Hz means that our eyes receive just more than four hundred trillion light waves every second! (WOW!)‏

16. Frequency and Wavelengths As wavelength increases, the frequency decreases. Think of it this way, if there are a lot of little waves hitting the beach quickly, they could be said to have a short wavelength and a high frequency. If there are only a few big waves hitting beach slowly, they would have a long wavelength and a lower frequency/

17. Waves and Cycles The two basic quantities which describe a light wave are the frequency f, of the wave (usually given in hertz, HZ, or cycles per second), and the wavelength, . These quantities are related to each other and to the speed of light c, by: λƒ = c

18. Amplitude Amplitude is the magnitude of a signal. As represented on a sine wave, it is the intensity of a wave.

19. Amplitude Higher & Lower Amplitudes of Sine waves @ Common Frequencies

20. Amplitude Amplitude of a light wave is what our eyes perceive as brightness. The greater the amplitude of a light wave, the further the wave is displaced from the midline, and brighter the light. ½

21. End Part 1

22. Behavior of Light Light speed can change depending on the material it goes through. When light speed changes, the behavior of light changes.

23. Absorption When trying to darken a room, use dark materials. The reason is that light is absorbed by dark colors, close to black. Have you ever noticed that some outdoor athletes, like football players, put black streaks under their eyes? The “eye black” absorbs the sunlight, reducing reflections to the eyes.

24. Mixing Colors of Light You may remember playing with paints and inks that yellow and blue make green, and mixing all your paints usually creates black. It’s different with light. Here’s how: Black is defined as the absence of light. White is the perceived color when red, blue, and green are present in equal proportions.

25. Chromaticity Diagram Notice that there is no black light represented on the diagram.

26. “Black Light” THERE IS NO SUCH THING AS BLACK COLORED LIGHT; BLACK IS CREATED BY THE ABSENCE OF LIGHT

27. Of Interest… When we see a field of green grass, our brains see that grass as green, because the grass absorbs the blue and red parts of the sunlight illuminating it. Only the proper green wavelength is reflected back for interpretation by our eyes and brains.

28. Of Interest… If none of the light was absorbed, it would appear whilte. If all of the light were absorbed, it would appear black. If we try seeing the field at night, it would appear gray because of our night vision is sensitive to grayscale more than to saturation or hue.

29. “Defining” Color Value should be thought of as a grayscale.

30. “Defining” Color Hue is the color represented.

31. Color Temperature Color temperature is a scientific measurement for expressing the distribution of the colors radiating from a light source, expressed on the Kelvin Scale.

32. Color Temperature The higher the color temperature, the bluer the light. The lower the color temperature, the redder the light is.