UNIT 5
PART A |
chromaticity |
quality of a color (hue/saturation) |
chromaticity diagram |
visual representation of all perceivable colors; mixture of colors + comparison |
RGB |
additive color model; combining at full intensity produces white |
YIQ |
Y - luminance component; grayscale information |
CMY |
subtractive(from reflected white) color model; mixing inks/dyes/pigments; |
HSV/HLS |
H - Hue (pure color); HSV - single hexcone; HLS - double hexcone
S - saturation (vibrancy)
V - value(brightness) |
key frame systems |
important frames (keyframes); start and end; intermediate frames (tweening/in-betweening) |
Bitmap animation |
manipulating pixels/blocks (Frame-buffer animation) |
Design of Animation Sequences |
outline the storyboard or script.
define motion sequence, objects, and keyframe positions. |
motion specification |
define how objects move and transform over time; paths, kinematics, dynamics |
HSV preferred over RGB when selecting hue, brightness and vibrancy
RGB to YIQ
Y=0.299R+0.587G+0.114B |
I=0.5959R−0.2746G−0.3213B |
Q=0.2115R−0.5227G+0.3112B |
Advantages of YIQ |
1. Bandwidth efficiency |
more for Y; less for I & Q |
2. Monochrome compatibility |
Y carries brightness |
3. Perceptual separation |
matches human vision |
4. Reduced interference |
improved signal quality (separating luminance & chrominance) |
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HSV
H (Hue): Base color (0°–360°)
S (Saturation): Color intensity (0–100%)
V (Value): Brightness (0–100%) |
Steps for Palette Creation |
Step 1 – Choose Fixed Hue
Step 2 – Vary Saturation
Step 3 – Vary Value
Step 4 – Generate Color Grid/Matrix |
CMY to RGB
Red (R) = M + Y
Green (G) = C + Y
Blue (B) = C + M |
C absorbs Red
M absorbs Green
Y absorbs Blue |
mixing two primary colors subtracts two wavelengths of light, leaving only the color perceived as their overlap (a secondary color: R, G, or B). |
Characteristics of light
Wavelength: defines hue (color)
Intensity: defines brightness
Additive Nature: combines to form white → basis for RGB |
Impact on RGB |
Structure |
Based on Red, Green, Blue (human cone sensitivity) |
Represented as a 3D color cube |
Operation |
Additive mixing: R+G+B=white; (0,0,0)=black |
varying intensity values (0–255) |
Directly used in display devices (monitors, TVs)
Raster and Keyframe animation
Raster Animation |
Key-Frame Animation |
Definition: Frame-by-frame images |
Definition: Store key frames, generate in-betweens |
Data Structures: Bitmap frames, frame buffer |
Data Structures: Key frames, control points, interpolation (linear/spline) |
Process: Each frame stored and displayed sequentially |
Process: Interpolate intermediate frames between key frames |
Storage: high |
Storage: low |
Motion realism: exact |
Motion realism: smooth |
Editing: Difficult |
Editing Easy: |
Short, detailed animations |
Long animations with smooth motion |
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Chromaticity diagram
Represents Visible Color Range |
2D slice, 3D color plane; isolate hue and saturation |
horseshoe-shaped boundary; pure spectral colors |
line of purples: non-spectral colors (mistures; connects red + blue) |
Interior = all visible color combinations |
Meaning of Points |
Each point = specific color (hue (angle) + saturation (distance from center) |
Center → white/gray (achromatic) |
Boundary points = maximum saturation for that hue |
lines between points - mixture |
Placement of Primary Colors |
Primaries (RGB) are fixed points inside diagram (not at extremes; form a triangle) |
triangle formed shows color gamut (subset colors) |
Limitations: |
Limited gamut (triangle ≠ full diagram)
Primaries not at extremes
Cannot represent all visible colors |
Keyframe vs. Procedural
Keyframe |
Procedural |
Control: High (artistic, stylized motion) |
Control: Limited (function-driven) |
Realism: Depends on animator |
Realism: High (follows physics) |
Computation: Low runtime, high manual effort |
Computation: Higher runtime, easy parameter changes |
more control/style |
less control/style |
Best for stylized animation |
Best for realistic motion |
HLS vs. HSV
HLS |
HSV |
Uses Lightness (L) |
Uses Value (V) |
Pure color at L = 50% |
Pure color at V = 100% |
L controls brightness + contrast clearly |
Less intuitive for contrast control |
HLS : better for harmony (consistent palette), contrast + more reliable
HLS is more logical and error-proof for UI design due to better control over lightness and contrast
Squash & Stretch
Idea: Deform mesh based on velocity & impact, not uniform scaling |
Algorithm |
Step 1 – Calculate Deformation Axis |
normalized velocity vector |
Step 2 – Determine Deformation Magnitude: |
scalar factor from object's speed (impact - sudden velocity change) |
Step 3 – Apply Volume-Preserving Deformation: |
Scale along axis by k, others by 1/√k → volume preserved |
At impact → use surface normal |
Parameters |
Mesh vertices; Velocity; Impact normal; Deformation factor (k); Damping/stiffness |
Mathematical foundation |
affine transformations; volume conservation |
directional scaling matrix |
spring-damper model |
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