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Study GUIDE for INTRODUCTION
TO COMPUTER GRAPHICS
Complete
What are Computer Graphics
Image Processing?
Scene
description
Computer
graphics
Image analysis &
computer vision
Why bother with CG & IP?
+ All visual computer output depends on CG
♦ printed output (laser/ink jet/phototypesetter)
♦ monitor (CRT/LCD/plasma/DMD)
♦ all visual computer output consists of real
images generated by the computer from some
internal digital image
+Much other visual imagery depends on CG & IP
♦ TV & movie special effects & post-production
♦ most books,
magazines,
catalogues,
brochures, junk
mail, newspapers,
packaging, posters,
Image
capture
image
Image
display
Image processing
What are CG & IP used for?
+2D computer graphics
♦ graphical user interfaces: Mac, Windows, X…
♦ graphic design: posters, cereal packets…
♦ typesetting: book publishing, report writing…
+Image processing
♦ photograph retouching: publishing, posters…
♦ photocollaging: satellite imagery…
♦ art: new forms of artwork based on digitised images
+3D computer graphics
♦ visualisation: scientific, medical, architectural…
♦ Computer Aided Design (CAD)
♦ entertainment: special effect, games, movies…
+ Background
Course Structure
♦ What is an image? Human vision. Resolution and
quantisation. Storage of images in memory. [1 lecture]
+ Rendering
♦ Perspective. Reflection of light from surfaces and
shading. Geometric models. Ray tracing. [3 lectures]
+ Graphics pipeline
♦ Polygonal mesh models. Transformations using matrices
in 2D and 3D. Homogeneous coordinates. Projection:
orthographic and perspective. [1 lecture]
+ Graphics hardware and modern OpenGL
♦ Vertex processing. Rasterisation. Fragment processing.
Working with meshes and textures. [2 lectures]
+ Technology
♦ Colour spaces. Output devices: brief overview of
display and printer technologies. [1 lecture]
Introduction to Computer Graphics
+ Background
♦ What is an image?
♦ Human vision
♦ Resolution and quantisation
♦ Storage of images in memory
+ Rendering
+ Graphics pipeline
+ Graphics hardware and modern OpenGL
+ Technology
What is an image?
+two dimensional function
+value at any point is an intensity or colour
+not digital!
Image capture
+a variety of devices can be used
♦ scanners
■ line CCD (charge coupled device) in a
flatbed scanner
■ spot detector in a drum scanner
♦ cameras
■ area CCD
■ CMOS camera chips
Heidelber
g drum
scanner
area CCD
www.hll.mp
g.de
flatbed
scanner
www.nuggetlab.
com
The image of
the Heidelberg
drum scanner
and many other
images in this
section come
from “Handbook
of Print Media”,
by Helmutt
Kipphan,
Springer-Verlag,
Sampling
+a digital image is a rectangular array of
intensity values
+each value is called a pixel
♦ “picture element”
+sampling resolution is normally measured
in pixels per inch (ppi) or dots per inch
(dpi)
♦ computer monitors have a resolution around 100 ppi
♦ laser and ink jet printers have resolutions
between 300 and 1200 ppi
♦ typesetters have resolutions between 1000 and 3000
ppi
Sampling resolution
Quantisation levels
8 bits
(256 levels)
1 bit
(2 levels)
7 bits
(128 levels)
2 bits
(4 levels)
6 bits
(64 levels)
3 bits
(8 levels)
5 bits
(32 levels)
4 bits
(16 levels)
What is required for vision?
+illumination
■ some source of light
+objects
■ which reflect (or transmit) the light
+eyes
■ to capture the light as an image
direct viewing transmission reflection
The workings of the human visual
system
+to understand the requirements of
displays (resolution, quantisation and
colour) we need to know how the human
eye works...
The lens of the eye forms an
image of the world on the
retina: the back surface of
the eye
Structure of the human eye
+ the retina is an array
of light detection
cells
+ the fovea is the high
resolution area of the
retina
+ the optic nerve takes
signals from the retina
to the visual cortex in
the brain
