Multimedia Technology Lecture 12 | Color Theory | Color Data | Color in Images | RGB
Contents Of Lecture
- Color Science: Light and Spectra
- Spectrophotometer
- Human Vision
- Color
- The Eye
- Color Blindness
- RGB - Additive Color
- HSB Model
- CMYK Model
- Printing Press Process
- Color Gamut
- CLUT OR Palette
- History Of Colour
- Properties and Attributes of Color
Color, Color properties, history of Color, RGB, CMYK
Multimedia Technology: Chapter 4 - The Science and Art of Color in Images and Video
Welcome back, everyone, to Zeeshan Academy! I'm Prof. Dr. Zeeshan Bhatti, and we're about to dive into one of the most fascinating and fundamental topics in all of multimedia: Color.
Color is not just a decorative element; it's a language. It conveys mood, draws attention, signifies meaning, and creates realism. But what we perceive as "red" or "blue" is actually a complex interplay between physics, biology, and technology. In this chapter, we'll unravel this mystery, moving from the physics of light to how your screen and printer recreate it.
Color Science: It All Starts with Light
To understand color, we must first understand light. Visible light is a small part of the electromagnetic spectrum that our eyes can detect. Sir Isaac Newton famously demonstrated that white light, when passed through a prism, splits into a spectrum of colors—red, orange, yellow, green, blue, indigo, and violet.
Light and Spectra: Every light source emits a unique combination of these wavelengths. The sun emits a relatively continuous spectrum, while a neon sign emits light only at specific wavelengths. A Spectrophotometer is a device used to measure the intensity of these wavelengths, giving us a precise "fingerprint" of a color's spectral makeup.
The Human Vision System: The Ultimate Color Renderer
The real magic of color happens not in the world, but inside our heads. Our eyes and brain are the ultimate color processing system.
The Eye: A Biological Sensor
Think of your eye as a sophisticated camera:
The cornea and lens focus light onto the retina.
The retina contains two types of photoreceptor cells: rods (for low-light vision) and cones (for color vision).
We have three types of cones, each sensitive to different wavelengths of light: Long (L) peaking in reds, Medium (M) in greens, and Short (S) in blues.
The brain interprets the signals from these three cone types to create our perception of millions of colors.
Color Blindness
When one or more types of cones don't function properly, it results in color vision deficiency, commonly known as color blindness. The most common form is difficulty distinguishing between red and green. This is a critical consideration for design—using color alone to convey information can exclude a significant portion of your audience. Always use color and symbols or patterns.
Modeling Color: From Light to Ink
Since we can't transmit light spectra directly through a computer, we use mathematical models to represent color. The two most important models are RGB and CMYK.
RGB: The Additive Color Model for Screens
This is the model of light. It's called additive because you start with black (no light) and add different colored lights to create new colors.
R (Red), G (Green), B (Blue) are the primary colors.
When combined at full intensity, they create white light.
This is the native model for all emissive devices: your computer monitor, smartphone, TV, and projector.
Each color channel is typically represented by 8 bits (0-255), allowing for 256 shades per channel. Combined, this gives us 256 x 256 x 256 = 16.7 million possible colors (24-bit "True Color").
The HSB/HSV Model: An Intuitive Approach
Working with RGB values like (123, 76, 201) isn't very intuitive for artists. Therefore, the HSB (Hue, Saturation, Brightness) or HSV (Hue, Saturation, Value) model was created.
Hue: The actual pigment or color family (e.g., red, yellow, blue). Represented as an angle on a color wheel (0-360°).
Saturation: The intensity or purity of the color. 0% is grayscale, 100% is fully vivid.
Brightness/Value: The lightness or darkness of the color. 0% is black, 100% is the full brightness of the chosen hue.
This model is the basis for color pickers in software like Photoshop and Premiere Pro because it aligns with how we naturally think about color.
CMYK: The Subtractive Color Model for Print
This is the model of pigments and inks. It's called subtractive because you start with a white surface (like paper) and subtract wavelengths of light by adding ink. The inks act as filters.
C (Cyan), M (Magenta), Y (Yellow) are the primary colors of ink.
In theory, combining CMY should produce black, but in practice, it creates a muddy brown. Therefore, K (Key - Black) is added to create deep shadows, improve contrast, and reduce ink costs.
This is the standard model for the Printing Press Process (both commercial and your home printer).
Color Gamut: The Realm of Reproducible Colors
Here's a critical concept that often causes confusion: not all colors can be reproduced by all devices. The range of colors a device can produce is called its Color Gamut.
The Challenge: The gamut of colors visible to the human eye is vast. The gamut of an RGB monitor is smaller, and the gamut of a CMYK printer is smaller still.
What this means: That brilliant, neon-red you see on your screen might be impossible to print with standard inks. It falls "outside" the CMYK gamut. This is why professionally printed materials can sometimes look less vibrant than their on-screen versions.
Modern Solutions: Newer standards like DCI-P3 and Rec. 2020 are expanding the gamut of high-end displays, getting us closer to the full spectrum we can see.
A Brief History of Color Technology
Understanding where we came from helps appreciate where we are. The history of color in media is a story of technological innovation.
Early Displays: Early computers were monochrome (green or amber text on a black screen). Introducing color was a major breakthrough.
The CLUT or Palette: Due to limited memory, early color systems (like those supporting 256 colors) used a Color Look-Up Table (CLUT). Instead of storing RGB values for every pixel, the system stored a palette of 256 specific colors. Each pixel held an index number (0-255) pointing to a color in this table. This was efficient but limiting for photographs.
The True Color Revolution: As processing power and memory grew, 24-bit "True Color" became the standard, freeing us from the constraints of the CLUT and enabling photorealistic imagery.
The Properties and Attributes of Color
To work with color professionally, you need a precise vocabulary. Let's define the key properties:
Hue: This is what we typically mean when we say "color." It's the attribute of a visual sensation according to which an area appears to be similar to one of the perceived colors: red, yellow, green, and blue, or a combination of them.
Saturation (or Chroma): This describes the intensity or purity of a color. A highly saturated color is vivid and strong. A desaturated color is muted and moves towards gray.
Lightness (or Value/Brightness): This refers to how light or dark a color is. Adding white increases lightness (creating a "tint"), while adding black decreases it (creating a "shade").
Mastering the relationship between these three properties is the key to creating harmonious and effective color schemes in your multimedia projects.
Conclusion: Color as a Core Competency
As you can see, color is far more than a simple choice from a palette. It's a deep field spanning physics, biology, and engineering. Understanding the difference between additive and subtractive models, the limitations of color gamuts, and the biology of perception will make you a more effective and intentional multimedia creator.
For your next task, I want you to open any image editing software. Create a brilliant red square in RGB mode. Then, without changing the color, change the document's color mode to CMYK. Observe how the color may shift to fit the smaller CMYK gamut. This simple exercise will make the theory of gamut limitation instantly real.
In our next chapter, we'll put images and color into motion as we explore the world of Video Compression and Codecs.
Until then, see the world in all its brilliant color!
Prof. Dr. Zeeshan Bhatti
Zeeshan Academy - https://www.youtube.com/@ZeeshanAcademy
RED
(High Voltage, I am Available, Only you can see, I will tease you, don’t touch me)
• Fire
• Blood
• Energy
• War
• Danger
• Strength
• Power
• Passion
• Love
• Desire
• Anger
Light red represents
joy, passion, sensitivity, and love. Pink signifies romance, love, and
friendship. It denotes feminine qualities and passiveness.
Dark red is associated with vigor, willpower, rage, anger, leadership, courage, longing, malice, and wrath.
Brown suggests stability and denotes masculine qualities.
Reddish brown is associated with harvest and fall
Orange (Creativity, Attraction, success you will get, Young)
—Joy
—Sunshine
—enthusiasm
—Fascination
—happiness
—Creativity
—determination
•attraction
•success
•encouragement
•stimulation
Dark orange can mean deceit and distrust.
Red-orange corresponds to desire, pleasure, domination, aggression, and thirst for action.
Gold evokes the feeling of prestige. The meaning of gold is illumination, wisdom, and wealth. Gold often symbolizes high quality.
Yellow (Sunshine, New Dawn, Intellect, Happiness)
— warming effect
— arouses cheerfulness
— generates muscle energy
— honor
— loyalty
— cowardice
— Dull (dingy) yellow represents caution, decay, sickness, and jealousy.
Light yellow is associated with intellect, freshness, and joy.
Green (Nature, healing power, hope )
— Growth
— Harmony
— Freshness
— Fertility
— Emotion Safety
— Pure Money
— hope
Dark green is associated with ambition, greed, and jealousy.
Yellow-green can indicate sickness, cowardice, discord, and jealousy.
Aqua is associated with emotional healing and protection.
Olive green is the traditional color of peace
Blue (Future, Dream, Depth Stability)
— trust
— Loyalty
— Wisdom
— Confidence
— intelligence
— faith
— Truth
— Heaven
— Sea
— Sky
— Ocean Depth
Light blue is associated with health, healing, tranquility, understanding, and softness.
Dark blue represents knowledge, power, integrity, and seriousness.
Purple (Power, Nobility, Luxury, can’t beat me)
— Wealth
— Extravagance
— Wisdom
— Dignity
— Independence
— Creativity
— Mystery
— Magic
— Royalty
— Artificial
Light purple evokes romantic and nostalgic feelings.
Dark purple evokes gloom and sad feelings. It can cause frustration.
White (God, Pure, Truth, Mother, I will be there for you)
— Goodness
— Innocence
— Purity
— color of perfection
— Safety
— Cleanliness
— Spirit
— Coolness
— Hospitals
— Doctors
— Sterility
What ever it takessss , whatever heart breakssss, I will be right there waiting for you. La..la.lala……lalalala
(a song…)
Black (Death, Evil)
— Power
— Elegance
— Formality
— Death
— Evil
— Mystery
— Fear
— Black holes
— Negative strength and authority
— Grief
— Sorrow
— Pain
I will destroy you, break you, give you pain, not leave you alone
