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CS-724 route
Unit 1 · Lesson 1 of 4 5 min

Definition, Scope and History of Computer Graphics

A blindfolded painter who only understands numbers can still paint anything, if the instructions are good enough.

Right now, the screen you're reading on is doing something astonishing. Around two million tiny lights are each being told — sixty times a second — exactly how much red, green and blue to glow. Nobody draws those pictures by hand. A computer, which only understands numbers, works them out.

So here's the puzzle this chapter solves: how does a pile of numbers become a picture you can see? And what exactly do we mean when we say "computer graphics"?

Strip away the fancy words and computer graphics is simply the use of computers to create, store, manipulate and display pictures and images. The picture might be a bar chart in Excel, a building plan in AutoCAD, a dragon in a film, or the little battery icon at the top of your phone.

The key word is create. In graphics, we usually start with a description — "a red circle of radius 3 centred at (5, 5)", or "a 3D model of a car, lit from the left" — and the computer turns that description into an image. That description is called a model, and turning it into pixels is called rendering.

Graphics has two close cousins that students often mix up. The cleanest way to keep them apart is to ask: what goes in, and what comes out?

  • Computer graphics: model (description) in → image out. You describe a scene; the computer draws it.
  • Image processing: image in → better or changed image out. Sharpening a blurry photo, brightening an X-ray, removing noise.
  • Computer vision: image in → description out. A camera sees a queue and reports "14 people waiting".
Model shapes, numbers, a scene Image a grid of pixels Computer graphics Computer vision Image processing
Computer graphics vs image processing vs computer vision. Three cousins, one question: what goes in and what comes out? Graphics goes model → image.

The journey from Sketchpad to your phone took about sixty years, and each step happened because someone hit a wall and invented a way round it:

  • 1950s: military computers such as MIT's Whirlwind and the SAGE air-defence system show radar data on CRT screens — graphics is born as a way to see data.
  • 1960s: Sketchpad (1963) brings interactive drawing; vector (random-scan) displays dominate because memory is far too expensive to store every pixel.
  • 1970s: memory gets cheaper, so raster displays with frame buffers appear; researchers at the University of Utah invent shading techniques (Gouraud, Phong) and model the famous "Utah teapot".
  • 1980s: personal computers and the graphical user interface (Apple Macintosh, 1984; Windows soon after) put graphics on ordinary desks.
  • 1990s: 3D graphics cards arrive for games; Toy Story (1995) proves whole films can be computer-made.
  • 2000s–today: programmable GPUs, smartphones, real-time ray tracing (from 2018), VR headsets and AI-generated images.

Notice the pattern: every leap came from hardware getting cheaper (memory, then GPUs), which let the same mathematical ideas run faster. The maths you'll learn in this course is old and stable; the hardware keeps catching up with it.

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