WELCOME TO COLOR 0 7 / 0 3 / 2 0 2 2 1 P r e p a r e d b y M D A L I H O S S A I N Prepared by MD ALI HOSSAI N Jr. Instructor. Fb: [email protected]
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WELCOME TO COLOR
Prepared by MD ALI HOSSAI NJr. Instructor. Fb: [email protected]
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The fiber-optic networks you read about are pipelines for information carried by light.
16.1 LIGHT CARRIES INFORMATION
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16.1 THE SPEED OF LIGHT
The speed at which light travels through air is approximately 300 million meters per second.
Light travels almost a million times faster than sound.
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16.1 CALCULATE TIME
Calculate the time it takes light and sound to travel the distance of one mile, which is 1,609 meters.
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16.1 REFLECTION AND REFRACTION
When light moves through a material it travels in straight lines.
When light rays travel from one material to another, the rays may reflect.
The light that appears to bounce off the surface of an object is shown by a reflected ray.
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16.1 REFLECTION AND REFRACTION
The light that bends as it crosses a surface into a material refracts and is shown as a refracted ray.
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16.2 COLOR AND VISION
Key Question:How do we see color?
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16.2 COLOR AND VISION
When all the colors of the rainbow are combined, we do not see any particular color.
We see light without any color. We call this combination of all the colors of light
"white light".
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HOW THE HUMAN EYE SEES COLOR
The retina in the back of the eye contains photoreceptors.
These receptors release chemical signals.
Chemical signals travel to the brain along the optic nerve.
optic nerve
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PHOTORECEPTORS IN THE EYE
Cones respond to three colors: red, green and blue.
Rods detect intensity of light: black, white, shades of gray.
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HOW WE SEE COLORS
Which chemical signal gets sent depends on how much energy the light has.
If the brain gets a signal from ONLY green cones, we see green.
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16.2 HOW WE SEE OTHER COLORS
The three color receptors in the eye allow us to see millions of different colors.
The additive primary colors are red, green, and blue.
We don’t see everything white because the strength of the signal matters.
All the different shades of color we can see are made by changing the proportions of red, green, and blue.
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16.2 HOW WE SEE THE COLOR OF THINGS
When we see an object, the light that reaches our eyes can come from two different processes:
1. The light can be emitted directly from the object, like a light bulb or glow stick.
2. The light can come from somewhere else, like the sun, and we see the objects by reflected light.
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16.2 HOW WE SEE THE COLOR OF THINGS
Colored fabrics and paints get color from a subtractive process.
Chemicals, known as pigments, in the dyes and paints absorb some colors and allow the color you actually see to be reflected.
Magenta, yellow, and cyan are the three subtractive primary colors.
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CONDITIONS OF COLOR
• Viewing environment• Viewing booth• Human factors• Background influence
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CONDITIONS OF COLOR
• Viewing Environment - Should be in a neutral environment. With no windows if possible. Fluorescent lighting should be kept at a minimum
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CONDITIONS OF COLOR
• Viewing Booth - Should be used at all costs. It provides a consistent standard (D50/D65) of lighting for viewing color.
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CONDITIONS OF COLOR
Human factor
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BACKGROUND
Influence
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BACKGROUND
Influence
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BACKGROUND
Influence
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BACKGROUND
Influence
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Color mixing procedure.
COLOR CONTD…
TWO KINDS OF COLOR MIXING.
Color mixing takes place when two or more colors come together to form a different color. There are two basic systems of mixing colors. One system of color mixing takes place when mixing colorants such as paint, ink and dyes.
The other method of color mixing takes place when two or more colored light sources are combined. An example of this type of mixing takes place when our eyes blend together the tiny dots or stripes that make up the color images on television and computer monitor screens.
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COLOR CONTD… The perception of color
• SUBJECTIVE COLOR means that a color changes in our head dependent on how our eyes and brain perceive it. A subjective color is the color it looks because of the way we see it.
SUBJECTIVE COLOR
• OBJECTIVE COLOR means a color would be independent of the way humans perceive the color. Objective colors would be immutable, never changing colors independent of human perception.
OBJECTIVE COLOR
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COLOR CONTD…
Color Wavelength.Red780 – 622
Orange622 – 597
Yellow597 – 577
Green577 – 492
Blue492 – 455
Violet455 – 390
1 Angstrom = 10-10 meters.
The order of colors in light, arranged from shortest wavelength to longest, is called the visible spectrum of light. The image below shows light's visible spectrum, which runs from violet to red. We might recognize the spectrum as the order of colors in a rainbow.
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COLOR MANAGEMENT CONTD…
visible and invisible light of color
The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light.
Each kind of light has a unique wavelength, but human eyes can only perceive a tiny slice of the full spectrum -- the very narrow range from red to violet. Microwaves, radio waves, x-rays and more are hiding, invisible, just beyond our perception.
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COLOR CONTD…
Use of visible and invisible light
Visible Light.
• Telescopes.• Microscopes.• Electronic devices, Etc.
Invisible Light.
• Microwaves.• Radio & TV waves.• Infrared (IR) rays.• Ultraviolet (UV) rays.• Gamma rays, Etc.
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These describe the gradations of gray values between black and white. The number of gray levels of an 8-bit gray level image is 256 (including black and white).
COLOR CONTD…
Gray levels.
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COLOR CONTD…
Gray Level Transformation.
Gray Level Transformation is the process of transforming an input image of some format to an output image comprised of gray scale data. Input sources range from images taken in the visual spectrum (e.g. photographs) to non-visible images (e.g. x-rays).
Gray-scale image converted from a color photograph
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COLOR CONTD…
The Importance of Color in Printing
To identify and specify necessary objects. To stimulate the senses.To make animated picture.To increase the quality of the printed product.To attract the subscriber.
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COLOR CONTD…
Color measurement factors.
Illumination of the medium.Ingredient of the subtract.Nature of the ingredient.Device to measure the color.
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Thank you
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