Graphics Raster Graphics cgvr korea ac kr Graphics

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

Contents n Display Hardware n n How are imaging system organized? Output Primitives n n How are images display? Raster Graphics Systems n n CGVR How can we describe shapes with primitives? Color Models n How can we describe and represent colors? cgvr. korea. ac. kr Graphics Lab @ Korea University

Display Hardware n Video Display Devices n n n CGVR Cathode Ray Tube (CRT) Liquid Crystal Display (LCD) Plasma panels Thin-film electroluminescent display Light-emitting diodes (LED) Hard-Copy Devices n n n Ink-jet printer Laser printer Film recorder Electrostatic printer Pen plotter cgvr. korea. ac. kr Graphics Lab @ Korea University

Cathode Ray Tube (CRT) cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University

Liquid Crystal Display (LCD) cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University

Raster Graphics cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University

Frame Buffer cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University

Frame Buffer Refresh n CGVR Refresh Rate n Usually 30~75 Hz cgvr. korea. ac. kr Graphics Lab @ Korea University

Color Frame Buffer 255 150 255 255 150 150 75 750 255 150 75 750 255 150 75 0 cgvr. korea. ac. kr 75 750 0 0 CGVR 0 0 Blue channel Green channel Red channel Graphics Lab @ Korea University

Color CRT cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University

Contents n Display Hardware n n How are imaging system organized? Output Primitives n n How are images display? Raster Graphics Systems n n CGVR How can we describe shapes with primitives? Color Models n How can we describe and represent colors? cgvr. korea. ac. kr Graphics Lab @ Korea University

Output Primitives CGVR Points n Lines n DDA Algorithm n Bresenham’s Algorithm n n Polygons Scan-Line Polygon Fill n Inside-Outside Tests n Boundary-Fill Algorithm n Antialiasing n cgvr. korea. ac. kr Graphics Lab @ Korea University

Points n CGVR Single Coordinate Position n Set the bit value(color code) corresponding to a specified screen position within the frame buffer y set. Pixel (x, y) x cgvr. korea. ac. kr Graphics Lab @ Korea University

Lines n CGVR Intermediate Positions between Two Endpoints n DDA, Bresenham’s line algorithms Jaggies = Aliasing cgvr. korea. ac. kr Graphics Lab @ Korea University

DDA Algorithm n CGVR Digital Differential Analyzer n 0 < Slope <= 1 o Unit x interval = 1 y 2 y 1 x 1 cgvr. korea. ac. kr x 2 Graphics Lab @ Korea University

DDA Algorithm n CGVR Digital Differential Analyzer n 0 < Slope <= 1 o n Unit x interval = 1 Slope > 1 o y 2 Unit y interval = 1 y 1 x 1 cgvr. korea. ac. kr x 2 Graphics Lab @ Korea University

DDA Algorithm n CGVR Digital Differential Analyzer n 0 < Slope <= 1 o n Slope > 1 o n Unit x interval = 1 Unit y interval = 1 y 2 -1 <= Slope < 0 o Unit x interval = -1 cgvr. korea. ac. kr x 1 x 2 Graphics Lab @ Korea University

DDA Algorithm n CGVR Digital Differential Analyzer n Slope >= 1 o n 0 < Slope < 1 o n y 2 Unit y interval = 1 -1 <= Slope < 0 o n Unit x interval = 1 Unit x interval = -1 y 1 x 2 Slope < -1 o Unit y interval = -1 cgvr. korea. ac. kr Graphics Lab @ Korea University

Bresenham’s Line Algorithm n CGVR Midpoint Line Algorithm n Decision variable NE Q n d > 0 : choose NE o n P(xp, yp) M E : dnew= dold+a+b d <= 0 : choose E o cgvr. korea. ac. kr : dnew= dold+a Graphics Lab @ Korea University

Bresenham’s Algorithm(cont. ) n Initial Value of d n Update d cgvr. korea. ac. kr CGVR Graphics Lab @ Korea University