# CS452/552; EE465/505. Color Display Issues

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 CS452/552; EE465/505 Color Display Issues

2 2

3 Outline! Color Display Issues Color Systems Dithering and Halftoning! Splines Hermite Splines Bezier Splines Catmull-Rom Splines Read: Angel, Chapter 8, section 8.13 Display Considerations Chapter 11, Curves and Surfaces Chapter 12, section Advanced Rendering: Ray-Tracing Lab#5 posted, due: April 22nd simple scene: platform & object; 1 light; shadow map; camera controls Project#2 posted due: April 23rd

4 Light mapping

5 Recursive Ray Tracer (Simple version) // starting point p, direction d, max # of steps; returns a color c (single light source) trace(p, d, step) { color local, reflected, transmitted; point q; normal n; if(step > max) return(background_color); q = intersect(p, d, status); if(status==light_source) return(light_source_color); if(status==no_intersection) return(background_color); n = normal(q); r = reflect(q, n); t = transmit(q,n); local = phong(q, n, r); reflected = trace(q, r, step+1); // recursive call transmitted = trace(q, t, step+1); // recursive call return(local + reflected + transmitted); }

6 Ray Tracing: Summary! Efficiency replace the recursion with iteration use bounding boxes to simplify the math used to compute intersections! Aliasing errors, due to sampling use a stochastic sampling method in which the decision on where to cast the next ray is based on the rays cast so far (used in Renderman)! Ray tracing is an inherently parallel process! There are many free ray tracers available

7 Next Topic: Displays & Color! Consider perceptual issues related to displays! Introduce chromaticity space Color systems Color transformations! Standard Color Systems Angel and Shreiner: Interactive Computer Graphics 7E Addison-Wesley 2015

8 Displays & Color! Problems that affect the quality of a display two different displays may have the same resolution, but display pixels at different sizes the colors displayed on two different monitors may differ map software-defined colors onto the display map brightness values onto the display RGB values are independent of display properties, but do not account for the full range of the human visual system! The range of displayable colors for a device is called its color gamut

9 Luminance and Color Images! Luminance Image Monochromatic Values are gray levels Analogous to working with black and white film or television! Color Image Has perceptional attributes of hue, saturation, and lightness Do we have to match every frequency in visible spectrum? No! E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

10 Perception Review! Light is the part of the electromagnetic spectrum between ~ nm! A color C(λ) is a distribution of energies within this range! Human visual system has two types of sensors Rods: monochromatic, night vision Cones: color sensitive Three types of cones! Consequently, only three values, the tristimulus values, are perceived by the brain E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

11 Color vision deficiency! red-green difficulty distinguishing between shades of red + green affects ~8% of males and ~0.5% of females in populations of North European ancestry! blue-yellow difficulty differentiating shades of blue and yellow affects males & females equally, < 1/10,000! achromatopsia cannot perceive any colors rare, < 1/30,000 for most populations

12 Tristimulus Values! The human visual center has three cones with sensitivity curves S 1 (λ), S 2 (λ), and S 3 (λ)! For a color C(λ), the cones output the tristimulus values T = S λ) C( λ) dλ 1 1 ( C(λ) T = S λ) C( λ) dλ 2 2 ( T = S λ) C( λ) dλ 3 3 ( cones optic nerve T 1, T 2, T 3 E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

13 Three Color Theory! Any two colors with the same tristimulus values are perceived to be identical! Thus a display (CRT, LCD, film) must only produce the correct tristimulus values to match a color! Is this possible? Not always Different primaries (different sensitivity curves) in different systems E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

14 The Problem! The sensitivity curves of the human are not the same as those of physical devices! Human: curves centered in blue, green, and green-yellow! CRT: RGB! Print media: CMY or CMYK! Which colors can we match and, if we cannot match, how close can we come? E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

15 Representing Colors! Consider a color C(λ)! It generates tristimulus values T 1, T 2, T 3 Write C = (T 1, T 2, T 3 ) Conventionally,we assume 1 T 1, T 2, T 3 0 because there is a maximum brightness we can produce and energy is nonnegative 1 C is a point in color solid C 1 T 3 T 2 T 1 1 E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

16 Producing Colors! Consider a device such as a CRT with RGB primaries and sensitivity curves! Tristimulus values T = R( λ) C( λ) dλ T = G( λ) C( λ) dλ T = B( λ) C( λ) dλ E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

17 Matching! This T 1, T 2, T 3 is dependent on the particular device! If we use another device, we will get different values and these values will not match those of the human cone curves! Need a way of matching and a way of normalizing E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

18 Color Systems! Various color systems are used Based on real primaries: RGB UVW CMYK HLS (aka HSB) NTSC YIQ (National Television System Committee) Theoretical XYZ! Prefer to separate brightness (luminance) from color (chromatic) information Reduce to two dimensions E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

19 Tristimulus Coordinates! For any set of primaries, define t = T T T Note: T t 3 = T T T t = T T T T 3 T + + 1,, 0 t t t = 1 t t 2 t E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

20 Maxwell Triangle 1 T 1 + T 2 +T 3 =1 1 1 color solid Project onto 2D: chromaticity space 1 t 1 + t 2 =1 t 1 possible colors t 2 1 E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

21 NTSC RGB 1 r+g+b=1 g r+g=1 r 1 E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

22 Producing Other Colors! However colors producible on one system (its color gamut) is not necessarily producible on any other! Note that if we produce all the pure spectral colors in the nm range, we can produce all others by adding spectral colors! With real systems (CRT, film), we cannot produce the pure spectral colors! We can project the color solid of each system into chromaticity space (of some system) to see how close we can get E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

23 Color Gamuts 600 nm spectral colors CRT colors printer colors producible color on CRT but not on printer unproducible color 350 nm producible color on both CRT and printer 750 nm E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

24 XYZ! Reference system in which all visible pure spectral colors can be produced! Theoretical systems, as there are no corresponding physical primaries! Standard reference system E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

25 Color Systems! Most correspond to real primaries National Television Systems Committee (NTSC) RGB matches phosphors in CRTs! Film both additive (RGB) and subtractive (CMY) for positive and negative film! Print industry CMYK (K = black) K used to produce sharp crisp blacks Example: ink jet printers E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

26 Color Transformations! Each additive color system is a linear transformation of another G G C = (T 1, T 2, T 3 ) = (T 1, T 2, T 3 ) B B R in R G B system R in RGB system E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

27 Additive and Subtractive Color! Additive color Form a color by adding amounts of three primaries CRTs, projection systems, positive film Primaries are Red (R), Green (G), Blue (B)! Subtractive color Form a color by filtering white light with cyan (C), Magenta (M), and Yellow (Y) filters Light-material interactions Printing Negative film E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

28 RGB: Red, Green, Blue! Primary colors: red, green, blue! Secondary colors: yellow = red+green cyan = green+blue magenta = blue+red! All colors white = red+green+blue black = no color C = T 1 R + T 2 G + T 3 B Color Cube

29 CMYK: Cyan, Magenta, Yellow, Black! Primary colors: cyan, magenta, yellow! Secondary colors: blue = cyan+magenta red = magenta+yellow green = yellow+cyan! All colors white = no color black = cyan+magenta+yellow for true black, add in black (+black) Also known as process color (used to print full-color images)

30 RGB, CMY, CMYK! Assuming 1 is max of a primary C = 1 R M = 1 G Y = 1 B! Convert CMY to CMYK by K = min(c, M, Y) C = C K M = M K Y = Y - K E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

31 Color Matrix! Exists a 3 x 3 matrix to convert from representation in one system to representation in another # &! \$! = M\$! \$ " %! Example: XYZ to NTSC RGB find in colorimetry references & \$ \$ \$ % T' T' T' T T T! Can take a color in XYZ and find out if it is producible by transforming and then checking if resulting tristimulus values lie in (0,1) #!!! " E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

32 YIQ! NTSC Transmission Colors! Here Y is the luminance arose from the need to separate brightness from chromatic information in TV broadcasting & Y# \$! \$ I! \$ % Q! " = & \$ \$ \$ % #& R# ! \$!! \$ G! 0.311!" \$ % B! "! Note luminance shows high green sensitivity E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

33 Other Color Systems! UVW: equal numerical errors are closer to equal perceptual errors! HLS: perceptual color (hue, saturation, lightness) Polar representation of color space Single and double cone versions E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

34 HSB: Hue, Saturation, Brightness! Hue is the actual color. It is measured in angular degrees counter-clockwise around the cone starting and ending at red=0 or 360 (yellow = 60, green = 120, etc.).! Saturation is the purity of the color, measured in percent from the center of the cone (0) to the surface (100).! Brightness is measured in percent from black (0%) to white (100%). grayscale axis from 0% (white) to 100% (black)

35 Gamma Correction! Intensity vs CRT voltage is nonlinear I = cv γ! Gamma correction (encoding) can code/decode luminance or tristimulus values! Can use a lookup table to correct! Human brightness response is logarithmic Equal steps in gray levels are not perceived equally Can use lookup table! CRTs cannot produce a full black Limits contrast ratio E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012

36 Dithering (digital halftoning)

37 Black/White Dithering

38 Color Dithering

39 Halftoning

40 Modeling Complex Shapes

41 What do we need from curves in Computer Graphics?! Local control of shape so that it is easy to build and modify! Stability! Smoothness and continuity! Ability to evaluate derivatives! Ease of rendering

42 Utah Teapot! Most famous data set in computer graphics! Widely available as a list of 306 3D vertices and the indices that define 32 Bezier patches

43 Curve Representations

44 Parameterization of a Curve

45 Polynomial Interpolation

46 Splines: Piecewise Polynomials

47 Piecewise Polynomials

48 Splines

49 Cubic Curves in 3D

50 Cubic Hermite Splines

51 Deriving Hermite Splines

52 Deriving Hermite Splines

53 Deriving Hermite Splines

54 The Cubic Hermite Spline Equation

55 Four Basis Functions for Hermite Splines

56 Piecing together Hermite Splines

57 Hermite Splines in Adobe Illustrator

58 Bezier s Idea! In graphics and CAD, we do not usually have derivative data! Bezier suggested using the same 4 data points as with the cubic interpolating curve to approximate the derivatives in the Hermite form

59 Bezier Splines

60 Approximating Derivatives p 1 located at u=1/3 p 1 p 2 p 2 located at u=2/3 p p0 p'(0) 1/ 3 1 p p2 p'(1) 1/ 3 3 slope p (0) slope p (1) p 0 u p 3

61 The Bezier Spline Matrix

62 Bezier Blending Functions

63 DeCasteljau Construction

64 Bezier Patches Using same data array P=[p ij ] as with interpolating form p( u, v) 3 3 = i= 0 j= 0 bi( u) b j ( v) p ij = u T M B P M T B v Patch lies in convex hull

65 Analysis! Although the Bezier form is much better than the interpolating form, we have the derivatives are not continuous at join points! Can we do better? Go to higher order Bezier More work Derivative continuity still only approximate Supported by OpenGL Apply different conditions Tricky without letting order increase

66 Catmull-Rom Splines

67 Constructing the Catmull-Rom Spline

68 Catmull-Rom Spline Matrix

69 Splines with More Continuity?

70 Comparison of Basic Cubic Splines

71 Natural Cubic Splines

72 B-Splines

73 B-Splines! Basis splines: use the data at p=[p i-2 p i-1 p i p i-1 ] T to define curve only between p i-1 and p i! Allows us to apply more continuity conditions to each segment! For cubics, we can have continuity of function, first and second derivatives at join points! Cost is 3 times as much work for curves Add one new point each time rather than three! For surfaces, we do 9 times as much work

74 B-Spline Basis

75 Other Common Types of Splines

76 Generalizing Splines! We can extend to splines of any degree! Data and conditions to not have to given at equally spaced values (the knots) Nonuniform and uniform splines Can have repeated knots Can force spline to interpolate points! Cox-deBoor recursion gives method of evaluation

77 NURBS! Nonuniform Rational B-Spline curves and surfaces add a fourth variable w to x,y,z Can interpret as weight to give more importance to some control data Can also interpret as moving to homogeneous coordinate! Requires a perspective division NURBS act correctly for perspective viewing! Quadrics are a special case of NURBS

78 How to Draw Spline Curves

79 Drawing Splines, continued

80 Summary

81 Project: Roller Coaster! use Catmull-Rom splines along with lighting and texture mapping to create a roller coaster simulation! runs in a first-person view, allowing the user to ride the coaster in an immersive environment

82 Animation

### Image Formation. Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico

Image Formation Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico 1 Objectives Fundamental imaging notions Physical basis for image formation

### Computer Graphics. Bing-Yu Chen National Taiwan University The University of Tokyo

Computer Graphics Bing-Yu Chen National Taiwan University The University of Tokyo Introduction The Graphics Process Color Models Triangle Meshes The Rendering Pipeline 1 What is Computer Graphics? modeling

### Game Programming. Bing-Yu Chen National Taiwan University

Game Programming Bing-Yu Chen National Taiwan University What is Computer Graphics? Definition the pictorial synthesis of real or imaginary objects from their computer-based models descriptions OUTPUT

### Introduction to Computer Graphics with WebGL

Introduction to Computer Graphics with WebGL Ed Angel Professor Emeritus of Computer Science Founding Director, Arts, Research, Technology and Science Laboratory University of New Mexico Image Formation

### Physical Color. Color Theory - Center for Graphics and Geometric Computing, Technion 2

Color Theory Physical Color Visible energy - small portion of the electro-magnetic spectrum Pure monochromatic colors are found at wavelengths between 380nm (violet) and 780nm (red) 380 780 Color Theory

### Visible Color. 700 (red) 580 (yellow) 520 (green)

Color Theory Physical Color Visible energy - small portion of the electro-magnetic spectrum Pure monochromatic colors are found at wavelengths between 380nm (violet) and 780nm (red) 380 780 Color Theory

### 3D graphics, raster and colors CS312 Fall 2010

Computer Graphics 3D graphics, raster and colors CS312 Fall 2010 Shift in CG Application Markets 1989-2000 2000 1989 3D Graphics Object description 3D graphics model Visualization 2D projection that simulates

### Computer Graphics. Bing-Yu Chen National Taiwan University

Computer Graphics Bing-Yu Chen National Taiwan University Introduction The Graphics Process Color Models Triangle Meshes The Rendering Pipeline 1 INPUT What is Computer Graphics? Definition the pictorial

### Lecture 1. Computer Graphics and Systems. Tuesday, January 15, 13

Lecture 1 Computer Graphics and Systems What is Computer Graphics? Image Formation Sun Object Figure from Ed Angel,D.Shreiner: Interactive Computer Graphics, 6 th Ed., 2012 Addison Wesley Computer Graphics

### INTRODUCTION. Slides modified from Angel book 6e

INTRODUCTION Slides modified from Angel book 6e Fall 2012 COSC4328/5327 Computer Graphics 2 Objectives Historical introduction to computer graphics Fundamental imaging notions Physical basis for image

### The Display pipeline. The fast forward version. The Display Pipeline The order may vary somewhat. The Graphics Pipeline. To draw images.

View volume The fast forward version The Display pipeline Computer Graphics 1, Fall 2004 Lecture 3 Chapter 1.4, 1.8, 2.5, 8.2, 8.13 Lightsource Hidden surface 3D Projection View plane 2D Rasterization

### Ray Tracing. Shandong University

Ray Tracing Shandong University Introduction OpenGL is based on a pipeline model in which primitives are rendered one at time - No shadows (except by tricks or multiple renderings) - No multiple reflections

### Reading. 2. Color. Emission spectra. The radiant energy spectrum. Watt, Chapter 15.

Reading Watt, Chapter 15. Brian Wandell. Foundations of Vision. Chapter 4. Sinauer Associates, Sunderland, MA, pp. 69-97, 1995. 2. Color 1 2 The radiant energy spectrum We can think of light as waves,

### Color and Shading. Color. Shapiro and Stockman, Chapter 6. Color and Machine Vision. Color and Perception

Color and Shading Color Shapiro and Stockman, Chapter 6 Color is an important factor for for human perception for object and material identification, even time of day. Color perception depends upon both

### Computer Graphics. Curves and Surfaces. Hermite/Bezier Curves, (B-)Splines, and NURBS. By Ulf Assarsson

Computer Graphics Curves and Surfaces Hermite/Bezier Curves, (B-)Splines, and NURBS By Ulf Assarsson Most of the material is originally made by Edward Angel and is adapted to this course by Ulf Assarsson.

### The Elements of Colour

Color science 1 The Elements of Colour Perceived light of different wavelengths is in approximately equal weights achromatic.

### Fall 2015 Dr. Michael J. Reale

CS 490: Computer Vision Color Theory: Color Models Fall 2015 Dr. Michael J. Reale Color Models Different ways to model color: XYZ CIE standard RB Additive Primaries Monitors, video cameras, etc. CMY/CMYK

### OUTLINE. Quadratic Bezier Curves Cubic Bezier Curves

BEZIER CURVES 1 OUTLINE Introduce types of curves and surfaces Introduce the types of curves Interpolating Hermite Bezier B-spline Quadratic Bezier Curves Cubic Bezier Curves 2 ESCAPING FLATLAND Until

### Introduction to color science

Introduction to color science Trichromacy Spectral matching functions CIE XYZ color system xy-chromaticity diagram Color gamut Color temperature Color balancing algorithms Digital Image Processing: Bernd

### SRM INSTITUTE OF SCIENCE AND TECHNOLOGY

SRM INSTITUTE OF SCIENCE AND TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY QUESTION BANK SUB.NAME: COMPUTER GRAPHICS SUB.CODE: IT307 CLASS : III/IT UNIT-1 2-marks 1. What is the various applications

### COMP3421. Global Lighting Part 2: Radiosity

COMP3421 Global Lighting Part 2: Radiosity Recap: Global Lighting The lighting equation we looked at earlier only handled direct lighting from sources: We added an ambient fudge term to account for all

### National Chiao Tung Univ, Taiwan By: I-Chen Lin, Assistant Professor

Computer Graphics 1. Graphics Systems National Chiao Tung Univ, Taiwan By: I-Chen Lin, Assistant Professor Textbook: Hearn and Baker, Computer Graphics, 3rd Ed., Prentice Hall Ref: E.Angel, Interactive

### Main topics in the Chapter 2. Chapter 2. Digital Image Representation. Bitmaps digitization. Three Types of Digital Image Creation CS 3570

Main topics in the Chapter Chapter. Digital Image Representation CS 3570 Three main types of creating digital images Bitmapping, Vector graphics, Procedural modeling Frequency in digital image Discrete

### Splines. Parameterization of a Curve. Curve Representations. Roller coaster. What Do We Need From Curves in Computer Graphics? Modeling Complex Shapes

CSCI 420 Computer Graphics Lecture 10 Splines Jernej Barbic University of Southern California Hermite Splines Bezier Splines Catmull-Rom Splines Other Cubic Splines [Angel Ch. 10] Roller coaster Next programming

### CS635 Spring Department of Computer Science Purdue University

Color and Perception CS635 Spring 2010 Daniel G Aliaga Daniel G. Aliaga Department of Computer Science Purdue University Elements of Color Perception 2 Elements of Color Physics: Illumination Electromagnetic

### Display Issues Week 5

CS 432/637 INTERACTIVE COMPUTER GRAPHICS Display Issues Week 5 David Breen Department of Computer Science Drexel University Based on material from Ed Angel, University of New Mexico Objectives Consider

### Splines. Parameterization of a Curve. Curve Representations. Roller coaster. What Do We Need From Curves in Computer Graphics? Modeling Complex Shapes

CSCI 420 Computer Graphics Lecture 8 Splines Jernej Barbic University of Southern California Hermite Splines Bezier Splines Catmull-Rom Splines Other Cubic Splines [Angel Ch 12.4-12.12] Roller coaster

### Fall CSCI 420: Computer Graphics. 4.2 Splines. Hao Li.

Fall 2014 CSCI 420: Computer Graphics 4.2 Splines Hao Li http://cs420.hao-li.com 1 Roller coaster Next programming assignment involves creating a 3D roller coaster animation We must model the 3D curve

### Curves and Surfaces 1

Curves and Surfaces 1 Representation of Curves & Surfaces Polygon Meshes Parametric Cubic Curves Parametric Bi-Cubic Surfaces Quadric Surfaces Specialized Modeling Techniques 2 The Teapot 3 Representing

### Interactive Computer Graphics A TOP-DOWN APPROACH WITH SHADER-BASED OPENGL

International Edition Interactive Computer Graphics A TOP-DOWN APPROACH WITH SHADER-BASED OPENGL Sixth Edition Edward Angel Dave Shreiner Interactive Computer Graphics: A Top-Down Approach with Shader-Based

Illumination and Shading Light sources emit intensity: assigns intensity to each wavelength of light Humans perceive as a colour - navy blue, light green, etc. Exeriments show that there are distinct I

### CHAPTER 1 Graphics Systems and Models 3

?????? 1 CHAPTER 1 Graphics Systems and Models 3 1.1 Applications of Computer Graphics 4 1.1.1 Display of Information............. 4 1.1.2 Design.................... 5 1.1.3 Simulation and Animation...........

### (0, 1, 1) (0, 1, 1) (0, 1, 0) What is light? What is color? Terminology

lecture 23 (0, 1, 1) (0, 0, 0) (0, 0, 1) (0, 1, 1) (1, 1, 1) (1, 1, 0) (0, 1, 0) hue - which ''? saturation - how pure? luminance (value) - intensity What is light? What is? Light consists of electromagnetic

### Digital Image Processing COSC 6380/4393. Lecture 19 Mar 26 th, 2019 Pranav Mantini

Digital Image Processing COSC 6380/4393 Lecture 19 Mar 26 th, 2019 Pranav Mantini What is color? Color is a psychological property of our visual experiences when we look at objects and lights, not a physical

### Design considerations

Curves Design considerations local control of shape design each segment independently smoothness and continuity ability to evaluate derivatives stability small change in input leads to small change in

### Rendering Curves and Surfaces. Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico

Rendering Curves and Surfaces Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico Objectives Introduce methods to draw curves - Approximate

### Until now we have worked with flat entities such as lines and flat polygons. Fit well with graphics hardware Mathematically simple

Curves and surfaces Escaping Flatland Until now we have worked with flat entities such as lines and flat polygons Fit well with graphics hardware Mathematically simple But the world is not composed of

### CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY CS2401 COMPUTER GRAPHICS QUESTION BANK

CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING CS2401 COMPUTER GRAPHICS QUESTION BANK PART A UNIT I-2D PRIMITIVES 1. Define Computer graphics. 2. Define refresh

### 2D Spline Curves. CS 4620 Lecture 13

2D Spline Curves CS 4620 Lecture 13 2008 Steve Marschner 1 Motivation: smoothness In many applications we need smooth shapes [Boeing] that is, without discontinuities So far we can make things with corners

### Lecture 12 Color model and color image processing

Lecture 12 Color model and color image processing Color fundamentals Color models Pseudo color image Full color image processing Color fundamental The color that humans perceived in an object are determined

### End-Term Examination

Paper Code: MCA-108 Paper ID : 44108 Second Semester [MCA] MAY-JUNE 2006 Q. 1 Describe the following in brief :- (3 x 5 = 15) (a) QUADRATIC SURFACES (b) RGB Color Models. (c) BSP Tree (d) Solid Modeling

Spectral Color and Radiometry Louis Feng April 13, 2004 April 13, 2004 Realistic Image Synthesis (Spring 2004) 1 Topics Spectral Color Light and Color Spectrum Spectral Power Distribution Spectral Color

### Curves and Surfaces Computer Graphics I Lecture 10

15-462 Computer Graphics I Lecture 10 Curves and Surfaces Parametric Representations Cubic Polynomial Forms Hermite Curves Bezier Curves and Surfaces [Angel 10.1-10.6] September 30, 2003 Doug James Carnegie

### Survey in Computer Graphics Computer Graphics and Visualization

Example of a Marble Ball Where did this image come from? Fall 2010 What hardware/software/algorithms did we need to produce it? 2 A Basic Graphics System History of Computer Graphics 1200-2008 Input devices

### OXFORD ENGINEERING COLLEGE (NAAC Accredited with B Grade) DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING LIST OF QUESTIONS

OXFORD ENGINEERING COLLEGE (NAAC Accredited with B Grade) DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING LIST OF QUESTIONS YEAR/SEM.: III/V STAFF NAME: T.ELANGOVAN SUBJECT NAME: Computer Graphics SUB. CODE:

### Color to Binary Vision. The assignment Irfanview: A good utility Two parts: More challenging (Extra Credit) Lighting.

Announcements Color to Binary Vision CSE 90-B Lecture 5 First assignment was available last Thursday Use whatever language you want. Link to matlab resources from web page Always check web page for updates

### CS130 : Computer Graphics Lecture 2: Graphics Pipeline. Tamar Shinar Computer Science & Engineering UC Riverside

CS130 : Computer Graphics Lecture 2: Graphics Pipeline Tamar Shinar Computer Science & Engineering UC Riverside Raster Devices and Images Raster Devices - raster displays show images as a rectangular array

### Topics and things to know about them:

Practice Final CMSC 427 Distributed Tuesday, December 11, 2007 Review Session, Monday, December 17, 5:00pm, 4424 AV Williams Final: 10:30 AM Wednesday, December 19, 2007 General Guidelines: The final will

### Intro to Modeling Modeling in 3D

Intro to Modeling Modeling in 3D Polygon sets can approximate more complex shapes as discretized surfaces 2 1 2 3 Curve surfaces in 3D Sphere, ellipsoids, etc Curved Surfaces Modeling in 3D ) ( 2 2 2 2

### GLOBAL EDITION. Interactive Computer Graphics. A Top-Down Approach with WebGL SEVENTH EDITION. Edward Angel Dave Shreiner

GLOBAL EDITION Interactive Computer Graphics A Top-Down Approach with WebGL SEVENTH EDITION Edward Angel Dave Shreiner This page is intentionally left blank. Interactive Computer Graphics with WebGL, Global

### Lecture 1 Image Formation.

Lecture 1 Image Formation peimt@bit.edu.cn 1 Part 3 Color 2 Color v The light coming out of sources or reflected from surfaces has more or less energy at different wavelengths v The visual system responds

### ITP 140 Mobile App Technologies. Colors

ITP 140 Mobile App Technologies Colors Colors in Photoshop RGB Mode CMYK Mode L*a*b Mode HSB Color Model 2 RGB Mode Based on the RGB color model Called an additive color model because adding all the colors

### Chapter 4 Color in Image and Video

Chapter 4 Color in Image and Video 4.1 Color Science 4.2 Color Models in Images 4.3 Color Models in Video 4.4 Further Exploration 1 Li & Drew c Prentice Hall 2003 4.1 Color Science Light and Spectra Light

### Digital Image Processing

Digital Image Processing 7. Color Transforms 15110191 Keuyhong Cho Non-linear Color Space Reflect human eye s characters 1) Use uniform color space 2) Set distance of color space has same ratio difference

### Lecture 11. Color. UW CSE vision faculty

Lecture 11 Color UW CSE vision faculty Starting Point: What is light? Electromagnetic radiation (EMR) moving along rays in space R(λ) is EMR, measured in units of power (watts) λ is wavelength Perceiving

### CS123 INTRODUCTION TO COMPUTER GRAPHICS. Describing Shapes. Constructing Objects in Computer Graphics 1/15

Describing Shapes Constructing Objects in Computer Graphics 1/15 2D Object Definition (1/3) Lines and polylines: Polylines: lines drawn between ordered points A closed polyline is a polygon, a simple polygon

### CSE 167: Lecture #7: Color and Shading. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011

CSE 167: Introduction to Computer Graphics Lecture #7: Color and Shading Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011 Announcements Homework project #3 due this Friday,

### The Viewing Pipeline Coordinate Systems

Overview Interactive Graphics System Model Graphics Pipeline Coordinate Systems Modeling Transforms Cameras and Viewing Transform Lighting and Shading Color Rendering Visible Surface Algorithms Rasterization

### CS130 : Computer Graphics Curves (cont.) Tamar Shinar Computer Science & Engineering UC Riverside

CS130 : Computer Graphics Curves (cont.) Tamar Shinar Computer Science & Engineering UC Riverside Blending Functions Blending functions are more convenient basis than monomial basis canonical form (monomial

### CSE 167: Lecture #6: Color. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011

CSE 167: Introduction to Computer Graphics Lecture #6: Color Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011 Announcements Homework project #3 due this Friday, October 14

### CS337 INTRODUCTION TO COMPUTER GRAPHICS. Describing Shapes. Constructing Objects in Computer Graphics. Bin Sheng Representing Shape 9/20/16 1/15

Describing Shapes Constructing Objects in Computer Graphics 1/15 2D Object Definition (1/3) Lines and polylines: Polylines: lines drawn between ordered points A closed polyline is a polygon, a simple polygon

### Computer Graphics. Instructor: Oren Kapah. Office Hours: T.B.A.

Computer Graphics Instructor: Oren Kapah (orenkapahbiu@gmail.com) Office Hours: T.B.A. The CG-IDC slides for this course were created by Toky & Hagit Hel-Or 1 CG-IDC 2 Exercise and Homework The exercise

### Computer Graphics Lecture 2

1 / 16 Computer Graphics Lecture 2 Dr. Marc Eduard Frîncu West University of Timisoara Feb 28th 2012 2 / 16 Outline 1 Graphics System Graphics Devices Frame Buffer 2 Rendering pipeline 3 Logical Devices

### Color. making some recognition problems easy. is 400nm (blue) to 700 nm (red) more; ex. X-rays, infrared, radio waves. n Used heavily in human vision

Color n Used heavily in human vision n Color is a pixel property, making some recognition problems easy n Visible spectrum for humans is 400nm (blue) to 700 nm (red) n Machines can see much more; ex. X-rays,

### Digital Image Processing. Introduction

Digital Image Processing Introduction Digital Image Definition An image can be defined as a twodimensional function f(x,y) x,y: Spatial coordinate F: the amplitude of any pair of coordinate x,y, which

### CSE 167: Introduction to Computer Graphics Lecture #6: Colors. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013

CSE 167: Introduction to Computer Graphics Lecture #6: Colors Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013 Announcements Homework project #3 due this Friday, October 18

### Announcements. Lighting. Camera s sensor. HW1 has been posted See links on web page for readings on color. Intro Computer Vision.

Announcements HW1 has been posted See links on web page for readings on color. Introduction to Computer Vision CSE 152 Lecture 6 Deviations from the lens model Deviations from this ideal are aberrations

### Global Rendering. Ingela Nyström 1. Effects needed for realism. The Rendering Equation. Local vs global rendering. Light-material interaction

Effects needed for realism Global Rendering Computer Graphics 1, Fall 2005 Lecture 7 4th ed.: Ch 6.10, 12.1-12.5 Shadows Reflections (Mirrors) Transparency Interreflections Detail (Textures etc.) Complex

### Computer Graphics Curves and Surfaces. Matthias Teschner

Computer Graphics Curves and Surfaces Matthias Teschner Outline Introduction Polynomial curves Bézier curves Matrix notation Curve subdivision Differential curve properties Piecewise polynomial curves

### Color and Light CSCI 4229/5229 Computer Graphics Fall 2016

Color and Light CSCI 4229/5229 Computer Graphics Fall 2016 Solar Spectrum Human Trichromatic Color Perception Color Blindness Present to some degree in 8% of males and about 0.5% of females due to mutation

### Color and Light CSCI 4229/5229 Computer Graphics Summer 2017

Color and Light CSCI 4229/5229 Computer Graphics Summer 2017 Solar Spectrum Human Trichromatic Color Perception Color Blindness Present to some degree in 8% of males and about 0.5% of females due to mutation

### ECE-161C Color. Nuno Vasconcelos ECE Department, UCSD (with thanks to David Forsyth)

ECE-6C Color Nuno Vasconcelos ECE Department, UCSD (with thanks to David Forsyth) Color so far we have talked about geometry where is a 3D point map mapped into, in terms of image coordinates? perspective

### CS 464 Review. Review of Computer Graphics for Final Exam

CS 464 Review Review of Computer Graphics for Final Exam Goal: Draw 3D Scenes on Display Device 3D Scene Abstract Model Framebuffer Matrix of Screen Pixels In Computer Graphics: If it looks right then

### Graphics Hardware and Display Devices

Graphics Hardware and Display Devices CSE328 Lectures Graphics/Visualization Hardware Many graphics/visualization algorithms can be implemented efficiently and inexpensively in hardware Facilitates interactive

### CS2401 COMPUTER GRAPHICS ANNA UNIV QUESTION BANK

CS2401 Computer Graphics CS2401 COMPUTER GRAPHICS ANNA UNIV QUESTION BANK CS2401- COMPUTER GRAPHICS UNIT 1-2D PRIMITIVES 1. Define Computer Graphics. 2. Explain any 3 uses of computer graphics applications.

### Image Formation. Camera trial #1. Pinhole camera. What is an Image? Light and the EM spectrum The H.V.S. and Color Perception

Image Formation Light and the EM spectrum The H.V.S. and Color Perception What is an Image? An image is a projection of a 3D scene into a 2D projection plane. An image can be defined as a 2 variable function

### Black generation using lightness scaling

Black generation using lightness scaling Tomasz J. Cholewo Software Research, Lexmark International, Inc. 740 New Circle Rd NW, Lexington, KY 40511 e-mail: cholewo@lexmark.com ABSTRACT This paper describes

### Objects 2: Curves & Splines Christian Miller CS Fall 2011

Objects 2: Curves & Splines Christian Miller CS 354 - Fall 2011 Parametric curves Curves that are defined by an equation and a parameter t Usually t [0, 1], and curve is finite Can be discretized at arbitrary

### this is processed giving us: perceived color that we actually experience and base judgments upon.

color we have been using r, g, b.. why what is a color? can we get all colors this way? how does wavelength fit in here, what part is physics, what part is physiology can i use r, g, b for simulation of

### CS770/870 Spring 2017 Color and Shading

Preview CS770/870 Spring 2017 Color and Shading Related material Cunningham: Ch 5 Hill and Kelley: Ch. 8 Angel 5e: 6.1-6.8 Angel 6e: 5.1-5.5 Making the scene more realistic Color models representing the

### Color and Light CSCI 4229/5229 Computer Graphics Fall 2018

Color and Light CSCI 4229/5229 Computer Graphics Fall 2018 Solar Spectrum Human Trichromatic Color Perception Color Blindness Present to some degree in 8% of males and about 0.5% of females due to mutation

### CS 445 HW#6 Solutions

CS 445 HW#6 Solutions Text problem 6.1 From the figure, x = 0.43 and y = 0.4. Since x + y + z = 1, it follows that z = 0.17. These are the trichromatic coefficients. We are interested in tristimulus values

### Animation & Rendering

7M836 Animation & Rendering Introduction, color, raster graphics, modeling, transformations Arjan Kok, Kees Huizing, Huub van de Wetering h.v.d.wetering@tue.nl 1 Purpose Understand 3D computer graphics

### Reading. 4. Color. Outline. The radiant energy spectrum. Suggested: w Watt (2 nd ed.), Chapter 14. Further reading:

Reading Suggested: Watt (2 nd ed.), Chapter 14. Further reading: 4. Color Brian Wandell. Foundations of Vision. Chapter 4. Sinauer Associates, Sunderland, MA, 1995. Gerald S. Wasserman. Color Vision: An

### Color Vision. Spectral Distributions Various Light Sources

Color Vision Light enters the eye Absorbed by cones Transmitted to brain Interpreted to perceive color Foundations of Vision Brian Wandell Spectral Distributions Various Light Sources Cones and Rods Cones:

### COMPUTER GRAPHICS, MULTIMEDIA AND ANIMATION, Second Edition (with CD-ROM) Malay K. Pakhira

Computer Graphics, Multimedia and Animation SECOND EDITION Malay K. Pakhira Assistant Professor Department of Computer Science and Engineering Kalyani Government Engineering College Kalyani New Delhi-110001

### CSE 167: Lecture #6: Color. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012

CSE 167: Introduction to Computer Graphics Lecture #6: Color Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012 Announcements Homework project #3 due this Friday, October 19

### CS452/552; EE465/505. Image Formation

CS452/552; EE465/505 Image Formation 1-15-15 Outline! Image Formation! Introduction to WebGL, continued Draw a colored triangle using WebGL Read: Angel, Chapters 2 & 3 Homework #1 will be available on

### Curves and Surfaces Computer Graphics I Lecture 9

15-462 Computer Graphics I Lecture 9 Curves and Surfaces Parametric Representations Cubic Polynomial Forms Hermite Curves Bezier Curves and Surfaces [Angel 10.1-10.6] February 19, 2002 Frank Pfenning Carnegie

### B-spline Curves. Smoother than other curve forms

Curves and Surfaces B-spline Curves These curves are approximating rather than interpolating curves. The curves come close to, but may not actually pass through, the control points. Usually used as multiple,

### CS559 Computer Graphics Fall 2015

CS559 Computer Graphics Fall 2015 Practice Final Exam Time: 2 hrs 1. [XX Y Y % = ZZ%] MULTIPLE CHOICE SECTION. Circle or underline the correct answer (or answers). You do not need to provide a justification

### Curves. Computer Graphics CSE 167 Lecture 11

Curves Computer Graphics CSE 167 Lecture 11 CSE 167: Computer graphics Polynomial Curves Polynomial functions Bézier Curves Drawing Bézier curves Piecewise Bézier curves Based on slides courtesy of Jurgen

### Interactive Graphics. Lecture 9: Introduction to Spline Curves. Interactive Graphics Lecture 9: Slide 1

Interactive Graphics Lecture 9: Introduction to Spline Curves Interactive Graphics Lecture 9: Slide 1 Interactive Graphics Lecture 13: Slide 2 Splines The word spline comes from the ship building trade

### Central issues in modelling

Central issues in modelling Construct families of curves, surfaces and volumes that can represent common objects usefully; are easy to interact with; interaction includes: manual modelling; fitting to

### CSE 167: Introduction to Computer Graphics Lecture #13: Curves. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2017

CSE 167: Introduction to Computer Graphics Lecture #13: Curves Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2017 Announcements Project 4 due Monday Nov 27 at 2pm Next Tuesday: