1 Computer Graphics chapter 1 Dr. Jehad Q. O. Alnihoud Phone: 3354

RM[1]-2 Books F.S. Hill, Computer Graphics Using OpenGL, Prentice-Hall (2001). Mason Woo, OpenGL Programming Guide, Addison Wesley (2000). Hearn and Baker, Computer Graphics, Prentice-Hall (1997).

RM[1]-3 Books (Supplementary reference) Foley, V. Dam, Feiner, Hughes, Computer Graphics Principles and Practice, 2/e, Addison Wesley, Edward Angel, Interactive Computer Graphics, Addison Wesley, Zhigang Xiang, Schaum’s Outlines: Computer Graphics, McGrawHill, Shreiner D, OpenGL Reference Manual, Addison-Wesley, 2000.

RM[1]-4 Course Assessment Coursework 50%  First Exam 15%  Second Exam 15%  Group Project10%  Lab 10% Final Exam 50% Attendance in both lecture and lab sessions is compulsory.

RM[1]-5 Graphics Applications Art and Entertainment  Animations  Movies  Commercials  Special Effects

RM[1]-6 Graphics Applications Image Processing  Analysis, Reconstruction  Medical Imaging  Movies

RM[1]-7 Graphics Applications Simulation  Modeling and Analysis  Virtual Environments

RM[1]-8 Graphics Applications Scientific Visualization  Data Representation and Plotting  3D Views

RM[1]-9 Graphics Applications CAD/CAM  Industrial Design  Structural Design  Surface Modeling

RM[1]-10 Graphics Software Packages Early graphics libraries:  GKS (Graphical Kernel System)  PHIGS OpenGL (Silicon Graphics) Java2D (Sun Microsystems) Java3D (Sun Microsystems) VRML (Silicon Graphics)

RM[1]-11 Graphics: Main Components Theory  Analytical Geometry  Vectors and Matrices Algorithms  Eg: Line drawing, Filling etc. Implementation  Programming (OpenGL)

RM[1]-12 Graphics Hardware Line Drawing Devices:  Eg. Pen Plotters  Advantages: Perfect lines, Sharp Diagrams  Disadvantages: Not suitable for filled regions.

RM[1]-13 Graphics Hardware Raster Devices: Create pictures by displaying dots  Eg: Video monitor, dot-matrix printer, laser printer,ink-jet printer, film recorder  Advantages: Filled, shaded regions are easily displayed  Disadvantages: Jaggies Pixel

RM[1]-14 Pixel Depth Pixel depth refers to the number of bits used to represent a pixel value. 1 bit/pixel: Levels (Bi-level image) 2 bits/pixel: Levels

RM[1]-15 Pixel Depth  1 bit per pixel produce 2 levels (bi- level image).  2 bits per pixel produce 4 levels.  8 bits per pixel produce 256 levels. In general, if the pixel depth is n, then it is possible to have 2 n levels.

RM[1]-16 Raster Display Most display used for computer graphics nowadays are raster displays. Image presented in display surface that contains certain number of pixels. Eg. 480 x 640 (r x c). Frame buffer is a region of memory sufficiently large to hold all the pixel values for display.

RM[1]-17 Frame Buffer System with 64 color (3 DACs):  Each DAC uses 2 bits/pixel.  Total color: 4 x 4 x 4 = 64  If the display surface is 1024 x 1280, then the memory required for frame buffer is MB Monochrome Video display:  Only one DAC required. 6 planes of memory in frame buffer gives 2 6 = 64 level of gray.

RM[1]-18 Frame Buffer System with 24 bit color (3 DACs):  Each DAC uses 8 bits/pixel. (Total 24 bits/pixel)  Total color: 2 8 x 2 8 x 2 8 = 2 24  If the display surface is 1024 x 1280, then the memory required for frame buffer is 3.75MB

RM Basis colors: R, G, B R: Red=[1, 0, 0] G: Green=[0, 1, 0] B: Blue=[0, 0, 1] C: Cyan=[0, 1, 1] M: Magenta=[1, 0, 1] Y:Yellow=[1, 1, 0] W:White=[1,1,1] K: Black=[0,0,0] Color Models: RGB Diagram RGB Model is used for colored light sources RGB Model is additive

RM[1]-20 Complementary Colors: Two colors that combine to form White. Eg. Red, Cyan. Gray Values: Every point on the primary diagonal has equal values for all the components. Color Models: RGB Cube

RM[1]-21 Basis colors: C, M, Y C: Cyan=[1, 0, 0] M: Magenta=[0, 1, 0] Y: Yellow=[0, 0, 1] R: Red=[0, 1, 1] G: Green=[1, 0, 1] B: Blue=[1, 1, 0] W:White=[0,0,0] K: Black=[1,1,1] Color Models: CMY Diagram CMY Model is used for colored pigments CMY Model is subtractive

RM[1]-22 Color Models: RGB CMY (r, g, b) RGB = (1,1,1)  (c, m, y) CMY Light A red colored surface absorbs cyan from a white light

RM[1]-23 Color Models: HSV HexCone

RM[1]-24 H (Hue): 0 to 360 degrees0: Red, 60: Yellow …. S (Saturation): 0 to 10: Axis, 1: Boundary V (Value): 0 to 10: Vertex, 1: Base Examples: Eg. Yellow: [60, 1.0, 1.0] Black: [ -, -, 0.0] White: [-, 0.0, 1.0] Color Models: HSV

RM[1]-25 RGB Color Definition (OpenGL)