1. Colors – part 1 K1066BI – Graphical Design Teppo Räisänen Teppo.raisanen@oamk.fi

2. Electromagnetic radiation There is a lot of electromagnetic radiation happening all around us Some of this is human generated ▫Radio and TV signals, mobile phones, microwave ovens etc Some of this comes from the space ▫Stars (sun)

3. Light Light is a name for a range of electromagnetic radiation that can be detected by human eye ▫Human eye can only detect small part of electromagnetic radiation

4. Light

5. Electromagnetic radiation can be understood as wave The intensity of the light is determined by amplitude The color of the light is determined by wavelength

6. Light Radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray

7. Light Radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray

8. Light White light is when all the colors of the visible spectrum are combined ▫We can use a prism to separate different wavelengths

9. Light

10. When light hits object most of it is absorbed and some scatter ▫Scattering happens when light ”bounces” off the object ▫Absorbtion happens when light ”sticks” to the object We see the scattered light

11. Light Thus it is the scattered light that gives objects their color ▫If something is white almost all light is scattered ▫If something is black almost all light is absorbed

12. Human eye Human eye works much like a camera ▫Each part plays a vital role ▫Cornea bends light through pupil ▫Lens focuses light to the back of the eye (retina) ▫Retina has photo- receptor nerve cells

13. Human eye Each part plays a vital role ▫Retina changes light into electrical impulses and sends them through the optic nerve to the brain where an image is perceived

14. Human eye In retina there are two types of light-sensitive photoreceptor cells used for vision ▫Rods ▫Cones

15. Human eye Cones are responsible for color vision ▫They function best in relatively bright light ▫They also see details and movement well ▫The most cone cells are in the center of the eye ▫4.5 million cells Rods are responsible for night vision ▫More sensitive than cones but do not see color ▫Can work with 100 times less light than cones ▫Are located in the outer edges of the retina ▫90 million cells

16. Human eye Cones are responsible for color vision ▫There are three types of cones ▫One for blue, red and green light ▫This is called trichromacy

17. Brain sees the images Eyes send electrical impulses to brain Brain processes the impulses and form images ▫Brain makes a ”best guess” of what the eyes tell it ▫Brain can fill in information that is missing ▫Thus we sometimes see things that are not actually there

18. Brain sees the images What we see depends on the information provided by our eyes and interpreted by our brain

19. Brain sees the images Close to 10% of people have some problems differenting colors ▫More common in males Most common color vision deficiency is problem seeing red-green ▫Deuteranomaly, 5% of males