1 Aliasing & Anti-Aliasing. 2 What is aliasing? An artifact (loss of detail and false details) Caused by discretization (finite resolution) A rasterized.

Slides:

Advertisements

Similar presentations

5.1 Si23_03 SI23 Introduction to Computer Graphics Lecture 5 – Drawing A Line.

Advertisements

Sampling and Reconstruction

Technische Universität München Fakultät für Informatik Computer Graphics SS 2014 Sampling Rüdiger Westermann Lehrstuhl für Computer Graphik und Visualisierung.

Introduction to Raster scan display C A E D C Computer Aided Engineering Design Centre.

30/9/2008Lecture 21 Computer Graphics Assistant Professor Dr. Sana’a Wafa Al-Sayegh 2 nd Semester ITGD3107 University of Palestine.

Computer Graphics Viewing, Rendering, Antialiasing گرد آوري و تاليف: دكتر احمد رضا نقش نيل چي دانشگاه اصفهان گروه مهندسي كامپيوتر.

1. 2 Blending: tells you how to specify a blending function that combines color values from a source and a destination. The final effect is that parts.

David Luebke1/19/99 CS 551/651: Antialiasing David Luebke

CS 551 / CS 645 Antialiasing. What is a pixel? A pixel is not… –A box –A disk –A teeny tiny little light A pixel is a point –It has no dimension –It occupies.

Aliasing & Antialiasing

CS 376 Introduction to Computer Graphics 02 / 05 / 2007 Instructor: Michael Eckmann.

Sampling, Aliasing, & Mipmaps

CMPE 466 COMPUTER GRAPHICS

Graphics Device Principles B.Sc. (Hons) Multimedia ComputingMedia Technologies.

Examples of antialiasing methods CS Introduction to Computer Graphics Autumn quarter, 2003 Additional slides for October 21 lecture.

CS 4731: Computer Graphics Lecture 22: Raster Graphics Part 3 Emmanuel Agu.

1 Image filtering Images by Pawan SinhaPawan Sinha.

Aliasing and Anti-Aliasing Copyright Zachary Wartell, University of North Carolina at Charlotte, All Rights Reserved Revision: 10/24/2007 3:38:00 AM ©Zachary.

1 Image filtering Hybrid Images, Oliva et al.,

CSI 421: Computer Graphics

Computer Graphics, KKU. Lecture 9

CS 450: COMPUTER GRAPHICS REVIEW: INTRODUCTION TO COMPUTER GRAPHICS – PART 1 SPRING 2015 DR. MICHAEL J. REALE.

Vector vs. Bitmap SciVis V

Raster vs Vector and Image Resolution By Josh Gallagan.

V Obtained from a summer workshop in Guildford County July, 2014

CSC418 Computer Graphics n Aliasing n Texture mapping.

Sampling and Antialiasing CMSC 491/635. Abstract Vector Spaces Addition –C = A + B = B + A –(A + B) + C = A + (B + C) –given A, B, A + X = B for only.

Sampling theorem In order to accurately reconstruct a signal from a periodically sampled version of it, the sampling frequency must be at least twice the.

CS 431/636 Advanced Rendering Techniques

David Luebke 1 9/4/2015 CS 551/651: Advanced Computer Graphics Antialiasing Continued: Prefiltering and Supersampling.

March Shape Drawing Algorithms Shmuel Wimer Bar Ilan Univ., Engineering Faculty.

CGMB214: Introduction to Computer Graphics

IT- 601: Computer Graphics Lecture-03 Scan Conversion

Computer Graphics Computer Graphics is everywhere: Visual system is most important sense: High bandwidth Natural communication Fast developments in Hardware.

Antialiasing CAP4730: Computational Structures in Computer Graphics.

3/4/04© University of Wisconsin, CS559 Spring 2004 Last Time Clipping Lines –Cohen-Sutherland: The use of outcodes and early reject/accept tests –Liang-Barsky:

Graphics Graphics Korea University cgvr.korea.ac.kr Raster Graphics 고려대학교 컴퓨터 그래픽스 연구실.

CS-321 Dr. Mark L. Hornick 1 Graphics Display Hardware Display technologies CRT LCD Storage tube Drawing methods Vector Raster Architecture.

Computer Graphics An Introduction. What’s this course all about? 06/10/2015 Lecture 1 2 We will cover… Graphics programming and algorithms Graphics data.

10/26/04© University of Wisconsin, CS559 Fall 2004 Last Time Drawing lines Polygon fill rules Midterm Oct 28.

1 Introduction Line attribute Color and gray scale Area filled attribute Anti-aliasing.

CS 450: COMPUTER GRAPHICS ANTIALIASING SPRING 2015 DR. MICHAEL J. REALE.

Image Processing Basics. What are images? An image is a 2-d rectilinear array of pixels.

Digital Media Dr. Jim Rowan ITEC So far… We have compared bitmapped graphics and vector graphics We have discussed bitmapped images, some file formats.

Attributes of drawing elements

Duy & Piotr. How to reconstruct a high quality image with the least amount of samples per pixel the least amount of resources And preserving the image.

CSC/FAR 020, Computer Graphics, October 20, 2014 Dr. Dale E. Parson Outline for week 8, Type tools.

Attributes of Graphics Primitives Hearn & Baker Chapter 4 Some slides are taken from Robert Thomsons notes.

UniS CS297 Graphics with Java and OpenGL Blending.

CS-321 Dr. Mark L. Hornick 1 Graphics Displays Video graphics adapter Monitor.

Digital Media Lecture 5: Vector Graphics Georgia Gwinnett College School of Science and Technology Dr. Jim Rowan.

CS559: Computer Graphics Lecture 12: Antialiasing & Visibility Li Zhang Spring 2008.

Guilford County SciVis V104.03

CS552: Computer Graphics Lecture 17: Scan Conversion (Special Cases)

Attributes of Graphics Primitives Chapter 4

IS502:M ULTIMEDIA D ESIGN FOR I NFORMATION S YSTEM D IGITAL S TILL I MAGES Presenter Name: Mahmood A.Moneim Supervised By: Prof. Hesham A.Hefny Winter.

Graphics Basic Concepts 1.  A graphic is an image or visual representation of an object.  A visual representation such as a photo, illustration or diagram.

Antialiasing. What is alias? Alias - A false signal in telecommunication links from beats between signal frequency and sampling frequency (from dictionary.com)

Attributes of Graphics Primitives Hearn & Baker Chapter 4

(c) 2002 University of Wisconsin, CS559

IT- 601: Computer Graphics Lecture-03 Scan Conversion

Midterm Review Computer Graphics Hardware Point and Line Drawing

Sampling and Antialiasing

Antialiasing Dr. Scott Schaefer.

Methods Anti-Aliasing Super Sampling

Drawing Issues Drawing Coordinate Systems Drawing with Pixels CS-321

CS654: Digital Image Analysis

CSC418 Computer Graphics Aliasing Texture mapping.

Presentation transcript:

1 Aliasing & Anti-Aliasing

2 What is aliasing? An artifact (loss of detail and false details) Caused by discretization (finite resolution) A rasterized line is an Alias of the ideal line

CS-321 Dr. Mark L. Hornick 3 What is Aliasing? (DSP Viewpoint) Low sampling frequency distorts signal

CS-321 Dr. Mark L. Hornick 4 Aliasing Line Examples Non-horizontal lines distorted (primarily) Vertical lines ok? (dimmer? Both CRT & LCD?) Oblique lines “jagged” How can we compensate?

CS-321 Dr. Mark L. Hornick 5 Aliasing in Graphic Displays Sampling issue Not really “sampling” a line But generating “misplaced” points What can we do? Increase screen resolution? Add extra information another way? Manipulate pixel intensity?

CS-321 Dr. Mark L. Hornick 6 Supersampling

CS-321 Dr. Mark L. Hornick 7 A Better Algorithm Assume that lines have normal thickness Superimpose the “wide” line on the subpixels Intensity: ~3/9 ~8/9

CS-321 Dr. Mark L. Hornick 8 Weighting Masks UniformCenter weighted

CS-321 Dr. Mark L. Hornick 9 Example Computer Graphics, Foley et al., Addison-Wesley, 1996, p. 134.

CS-321 Dr. Mark L. Hornick 10 Line Intensity Effects Pixels per unit length Fewer for diagonal lines anti-aliasing compensates Display device effects CRT’s Vertical lines appear dimmer than horizontal  Why? How about LCDs?

CS-321 Dr. Mark L. Hornick 11 Anti-alias example 1 Line drawn in PowerPoint

CS-321 Dr. Mark L. Hornick 12 Another example Line drawn in PowerPoint

CS-321 Dr. Mark L. Hornick 13 Color Effects Additional effects can be included Color R,G, and B intensities Background and fill Factor in their % of coverage Ex.  9-pixel grid (4 foreground/outline, 3 background, 2 fill)  C = (4*Red_fore + 3*Wht_back + 2*Yel_fill)/9 “Clear Type” in Windows (font smoothing)