Raster Display(1)

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Raster Display(1)

  1. 1. Raster Graphics 고려대학교 컴퓨터 그래픽스 연구실
  2. 2. Contents <ul><li>Display Hardware </li></ul><ul><ul><li>How are images display? </li></ul></ul><ul><li>Raster Graphics Systems </li></ul><ul><ul><li>How are imaging system organized? </li></ul></ul><ul><li>Output Primitives </li></ul><ul><ul><li>How can we describe shapes with primitives? </li></ul></ul><ul><li>Color Models </li></ul><ul><ul><li>How can we describe and represent colors? </li></ul></ul>
  3. 3. Display Hardware <ul><li>Video Display Devices </li></ul><ul><ul><li>Cathode Ray Tube (CRT) </li></ul></ul><ul><ul><li>Liquid Crystal Display (LCD) </li></ul></ul><ul><ul><li>Plasma panels </li></ul></ul><ul><ul><li>Thin-film electroluminescent display </li></ul></ul><ul><ul><li>Light-emitting diodes (LED) </li></ul></ul><ul><li>Hard-Copy Devices </li></ul><ul><ul><li>Ink-jet printer </li></ul></ul><ul><ul><li>Laser printer </li></ul></ul><ul><ul><li>Film recorder </li></ul></ul><ul><ul><li>Electrostatic printer </li></ul></ul><ul><ul><li>Pen plotter </li></ul></ul>
  4. 4. Cathode Ray Tube (CRT)
  5. 5. Liquid Crystal Display (LCD)
  6. 6. Raster Graphics
  7. 7. Frame Buffer
  8. 8. Frame Buffer Refresh <ul><li>Refresh Rate </li></ul><ul><ul><li>Usually 30~75 Hz </li></ul></ul>
  9. 9. Color Frame Buffer Blue channel Green channel Red channel 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0 255 150 75 0
  10. 10. Color CRT
  11. 11. Contents <ul><li>Display Hardware </li></ul><ul><ul><li>How are images display? </li></ul></ul><ul><li>Raster Graphics Systems </li></ul><ul><ul><li>How are imaging system organized? </li></ul></ul><ul><li>Output Primitives </li></ul><ul><ul><li>How can we describe shapes with primitives? </li></ul></ul><ul><li>Color Models </li></ul><ul><ul><li>How can we describe and represent colors? </li></ul></ul>
  12. 12. Output Primitives <ul><li>Points </li></ul><ul><li>Lines </li></ul><ul><ul><li>DDA Algorithm </li></ul></ul><ul><ul><li>Bresenham’s Algorithm </li></ul></ul><ul><li>Polygons </li></ul><ul><ul><li>Scan-Line Polygon Fill </li></ul></ul><ul><ul><li>Inside-Outside Tests </li></ul></ul><ul><ul><li>Boundary-Fill Algorithm </li></ul></ul><ul><ul><li>Antialiasing </li></ul></ul>
  13. 13. Points <ul><li>Single Coordinate Position </li></ul><ul><ul><li>Set the bit value(color code) corresponding to a specified screen position within the frame buffer </li></ul></ul>x y setPixel ( x , y )
  14. 14. Lines <ul><li>Intermediate Positions between Two Endpoints </li></ul><ul><ul><li>DDA, Bresenham’s line algorithms </li></ul></ul>Jaggies = Aliasing
  15. 15. DDA Algorithm <ul><li>Digital Differential Analyzer </li></ul><ul><ul><li>0 < Slope <= 1 </li></ul></ul><ul><ul><ul><li>Unit x interval = 1 </li></ul></ul></ul>x1 y1 x2 y2
  16. 16. DDA Algorithm <ul><li>Digital Differential Analyzer </li></ul><ul><ul><li>0 < Slope <= 1 </li></ul></ul><ul><ul><ul><li>Unit x interval = 1 </li></ul></ul></ul><ul><ul><li>Slope > 1 </li></ul></ul><ul><ul><ul><li>Unit y interval = 1 </li></ul></ul></ul>x1 y1 x2 y2
  17. 17. DDA Algorithm <ul><li>Digital Differential Analyzer </li></ul><ul><ul><li>0 < Slope <= 1 </li></ul></ul><ul><ul><ul><li>Unit x interval = 1 </li></ul></ul></ul><ul><ul><li>Slope > 1 </li></ul></ul><ul><ul><ul><li>Unit y interval = 1 </li></ul></ul></ul><ul><ul><li>-1 <= Slope < 0 </li></ul></ul><ul><ul><ul><li>Unit x interval = -1 </li></ul></ul></ul>x1 y2 x2 y1
  18. 18. DDA Algorithm <ul><li>Digital Differential Analyzer </li></ul><ul><ul><li>Slope >= 1 </li></ul></ul><ul><ul><ul><li>Unit x interval = 1 </li></ul></ul></ul><ul><ul><li>0 < Slope < 1 </li></ul></ul><ul><ul><ul><li>Unit y interval = 1 </li></ul></ul></ul><ul><ul><li>-1 <= Slope < 0 </li></ul></ul><ul><ul><ul><li>Unit x interval = -1 </li></ul></ul></ul><ul><ul><li>Slope < -1 </li></ul></ul><ul><ul><ul><li>Unit y interval = -1 </li></ul></ul></ul>x1 y1 x2 y2
  19. 19. Bresenham’s Line Algorithm <ul><li>Midpoint Line Algorithm </li></ul><ul><ul><li>Decision variable </li></ul></ul><ul><ul><li>d > 0 : choose NE </li></ul></ul><ul><ul><ul><li>: d new = d old +a+b </li></ul></ul></ul><ul><ul><li>d <= 0 : choose E </li></ul></ul><ul><ul><ul><li>: d new = d old +a </li></ul></ul></ul>NE M Q P(x p , y p ) E
  20. 20. Bresenham’s Algorithm(cont.) <ul><li>Initial Value of d </li></ul><ul><li>Update d </li></ul>

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