Pros- Color Flashcards
Define light.
- Light is a form of electromagnetic energy, distinct from radio waves or microwaves by the wavelength.
what range of wavelengths make up visible light?
the visible spectrum (380 nm to 700 nm)
- What are the 6 interactions between light and an object?
- what determnes the wavelengths we see?
Transmission: light passes through without deflection in the light path
Reflection: light bounces off object in 1 angle (no transmission)
Refraction: transmission through translucent objects (ie enamel) with a change in the direction of the light path
Diffraction: light transmitted from one beam becomes diffracted into many beams as it passes across an edge or passes a slit; bending light around corners
Absorption: all light is absorbed by the object- no transmission
Scattering: light bounces in all directions, through and reflecting
- The light that is not absorbed determines the wavelength that can be observed.
What are the 3 overiding principles to understanding color in dentistry?
Understanding:
- color in terms of physics and biology
- the optical properties of teeth
- the optical properties of restorative materials
What are the 3 factors of color?
- The light source (the Sun and light bulb)
- The object (natural tooth or ceramic/resin restoration)
- The observer (eyes)
What are the 3 dimensions of color?
Who discovered this? Who is the father of the color system?
when?
- Hue (the color or wavelength of light reflected)
Chroma (the concentration or saturation of an object)
Value (the brightness of an object)
- Forsius (the father of the color system)
- 1611
Who first explained the rainbow? When?
1611 De Dominis
Who discovered light refraction and the properties of different wavelengths? When?
Isaac Newton
1669
Describe cone cell fatigue? How do you restore cone cells?
When you stare too long @ a specific color, cone cells become fatigued and produce an afterimage due to imbalance of photo receptors Refresh (rest) cone cells by looking at a neutral gray color
What are the 3 types of cone cells and what wavelengths/colors are seen by them? Where are the cone cells located? How many?
Cones see color Short wavelength cells- Blue range Medium wavelengths- Green range Long wavelengths- Red range Macula lutes (fovea centralis) center of retina -0.3mm rod-free area Photosensitive pigments- photopsins 6-7 million cones
How many Rods in the eye?
Where are the rods located?
What is the photosensitive pigment?
Rods see what kind of light?
- 90 million rods
- Outer edges of retina
- Rhodopsin
- Light sensitive only (low light vision)
Painter’s (pigment) color system
- primary colors
- secondary colors- what? how are they made?
- tertiary colors: how are they made?
- Complimentary colors?
- What happens when you mix complimentary colors? What color do you get?
- Primary: Red, Yellow, Blue
- Secondary colors are from mixing 2 primaries
Y+B=G; R+B=P; R+Y=O
- Tertiary: mix a primary and a secondary color
- R+P; R+O; Y+G; Y+O; B+G; B+P - Complimentary: contrasting color- opposites on color wheel:
- R+G; Y+P; B+O - mixing complimentary colors is essentially mixing all primary colors
= brownish color
How can you correct for value (pigment system) X3 ways
- Add white to increase value, but decrease saturation 2.Add black: decrease value, decrease saturation??? 3. Adding a secondary color will decrease value Ex. orange A3- add blue
Is pigment (paint) an additive or subtractive color system?
Subtractive - start with white, adding color gives black (brown)
What are the subtractive CYM…
- Primary colors?
- Secondary colors?
- How are the subtractive primary colors created
- Why are they considered subtractive?
- what is the media of subtractive colors?
- primary colors: CMY (Cyan, Magenta, Yellow)
- secondary colors: RGB (Red-Cyan, Green-Magenta, Blue-Yellow)
- subtractive primary colors are formed when its secondary color is absorbed:
ex: primary Cyan is seen when Red is absorbed and Blue and Green are reflected.
- Subtractive color mixing is creating a new color by the removal of wavelengths from a light with a broad spectrum of wavelengths. Subtractive color mixing occurs when we mix paints, dyes, or pigments. When we mix paints, both paints still absorb all of the wavelengths they did previously, so what we are left with is only the wavelengths that both paints reflect. It is called subtractive mixing because when the paints mix, wavelengths are deleted from what we see because each paint will absorb some wavelengths that the other paint reflects, thus leaving us with a lesser number of wavelengths remaining afterward. When we mix colors using paint, or through the printing process, we are using the subtractive color method. Subtractive color mixing means that one begins with white and ends with black; as one adds color, the result gets darker and tends to black.
- Printers, photographs, transmissive media/slides and transparency (paint’s are also a subtractive media)
What are the RGB additive…
- Primary colors?
- Secondary colors?
- What do you see when you remove a primary color from white light?
- Why are they considered additive?
- what is the media of additive colors?
- additive primary colors: RGB
- additive secondary colors: CMY (Red-Cyan, Green-Magenta, Blue-Yellow)
- when you remove a primary color from white light, you will see its secondary color: ex: if you remove Red from white light, you will see Cyan (blue and green)
- Additive color mixing is creating a new color by a process that adds one set of wavelengths to another set of wavelengths. Additive color mixing is what happens when lights of different wavelengths are mixed. When we add all of the different wavelengths of sunlight, we see white light rather than many individual colors. It is called additive because all of the wavelengths still reach our eyes. additive because you begin mixing with black and end with white:
If we are working on a computer, the colors we see on the screen are created with light using the additive color method. Additive color mixing begins with black and ends with white; as more color is added, the result is lighter and tends to white.
- emission (light) (tv, computers etc)
- What is the CIELAB System?
- When?
- What are visual thresholds?
- What is 50:50% PT?
- What is the ideal 50:50% PT?
- What is 50:50% AT?
- Which PT or AT is the ultimate importance as a predictor of product acceptibility?
- What is the 50:50% AT of teeth?, gingiva?
- What is industry tolerance and what does it indicate?
- CIELAB color system is based on RGB/CMY models: it is a more mathmatically quantifiable than Munsell’s
- 1976
- Visual threshold is color match bw dental restortion and adjacent natural tooth
considering the magnitude and direction of color difference.
- 50:50% PT: perceptibility threshold: 50% of observers notice a difference in color while 50% notice no difference.
- color marches at or below 50:50% are ideal.
- 50:50% AT: acceptability threshold: 50% of observers consider the color difference requires correction, 50 % say difference is acceptable
- 50:50% AT is the ultimate importance as a predictor of product acceptibility
- 50:50% AT teeth: 2.7; gingiva: 4.6
- the cusion difference between the AT and PT is called industry tolerance. It indicates how far from the perceptible difference we can go and still have an acceptable color difference.
