1. A computer can store numbers, but a person needs to see a picture.

A computer's memory holds nothing but numbers. A human brain, by contrast, understands the world through images far faster than through lists of figures. Computer graphics exists to bridge that gap, turning data a machine can store into a picture a person can grasp.

• Computers are excellent at storing and processing numbers, and nothing else.
• Humans process a picture in milliseconds but read a table of numbers slowly.
• Nearly every useful task needs the machine and the person to communicate visually.
• We also want to picture things that have no photograph: imagined worlds, future buildings, molecules.
• The problem: how do you turn pure numbers into an image a human eye can read?

2. Computer graphics is the craft of creating and manipulating images with code.

Computer graphics is the discipline of using algorithms and mathematics to generate, change, and display visual images. It splits naturally into two great activities: describing a scene as data, called modeling, and turning that description into an actual picture, called rendering.

• It is a craft of code: images are produced by running mathematical algorithms.
• Modeling is describing what exists: the shapes, the colors, the lights, the camera.
• Rendering is computing the picture: turning that description into a grid of colored pixels.
• The field covers both still images and animation, both flat 2D and full 3D.
• The payoff: anything you can describe with numbers, you can turn into a visible image.

3. Computer graphics began in the early nineteen sixties with a light pen and a screen.

The field has a clear birth. In nineteen sixty-three, a graduate student named Ivan Sutherland built Sketchpad, a program that let a person draw directly on a computer screen. From that single demonstration grew films, games, and an entire industry.

• 1963 — Ivan Sutherland's Sketchpad lets a user draw on a screen with a light pen, founding the field.
• 1960s and 70s — universities like Utah develop core ideas: shading, hidden surfaces, curved shapes.
• 1970s and 80s — graphics enters film; Pixar grows from a research lab into a studio.
• 1990s — Toy Story, the first fully computer-generated feature film, proves the medium.
• 2000s onward — fast graphics chips put real-time 3D into every home, console, and phone.

4. Graphics work follows four stages: describe, transform, decide visibility, then color the pixels.

Almost every graphics task, simple or complex, moves through the same four stages. You first describe a scene, then transform it into the viewer's frame, then decide what is actually visible, and finally compute the color of every pixel.

• Stage one, describe: lay out the scene as data, the shapes, colors, lights, and camera.
• Stage two, transform: use math to position everything relative to where the viewer looks from.
• Stage three, visibility: work out which surfaces are seen and which are hidden behind others.
• Stage four, shading: for every visible pixel, compute its final color from light and material.
• The result is a finished grid of colored pixels, ready to send to the screen.

5. A scene description is just a structured list of objects, lights, and a camera.

Let us make the idea of a scene description concrete, because this is the shape of what modeling produces. On the panel is a tiny three-dimensional scene, written as structured text. Read it from the top. First, the camera. It has a position in space, three numbers, and a point it is looking at. Three numbers for position is how we locate anything in three dimensions, and we spend a whole class on that soon. Next, a light, of type sun, with a direction. Then the objects. The first is a sphere, with a radius, a position, and a color, three numbers for red, green, and blue. The second is a plane, a flat infinite ground. And that is the entire scene. Notice what this text is. It is not a picture. You cannot see a sphere here, only a description of one. This text is the model, the recipe. To get an actual image, a separate program called a renderer must read this description and compute, pixel by pixel, what a camera at that position would see. Model first, render second.

6. Computer graphics quietly powers films, games, design, science, and medicine.

Once you know what to look for, computer graphics is everywhere. It is not a niche craft for movie studios; it is a foundational technology woven through entertainment, work, research, and healthcare.

• Film and television: creatures, environments, and effects that no camera could capture.
• Games: entire interactive worlds rendered fresh dozens of times every second.
• Design and engineering: architects, product designers, and engineers model before they build.
• Science: simulations of galaxies, climate, and proteins made visible as images.
• Medicine: scanners turn the inside of a living body into a picture a doctor can read.

7. Trace the same scene description through the two halves of the field.

Let us walk one example through, so the two halves of the field lock into place. The goal, at the top, is simple. We want a finished image of a red sphere sitting on a floor. Half one, modeling. We describe the scene. We define a sphere with a center and a radius. We define a floor as a flat plane at height zero. We define a sun, a bright light from the upper left. And we define a camera, ten units back, aimed at the sphere. Look at what modeling has produced. A scene description. It is pure data, with not one pixel of an image in it yet. Now half two, rendering. The renderer takes that description and does something almost brutal in its simplicity. It loops over every pixel in the image. For a full high-definition picture, that is a little over two million pixels. For each one, it asks two questions. Which object does this pixel see? And given the sun and the material, what color should it be? Two million answers later, you have an image. Modeling describes. Rendering computes. That division of labor is the backbone of the whole field.

8. Every graphics decision trades realism against the time it takes to compute.

There is one tension that runs through this entire field and shapes nearly every choice in it. Making an image look more real almost always means more computation, and more computation means more time. The art of graphics is choosing where to spend.

• More realism means more math: accurate light, soft shadows, and fine detail are all expensive.
• More math means more time: a frame can take a millisecond or it can take many hours.
• Games sit at one extreme: they must finish a frame fast, so they approximate aggressively.
• Film sits at the other: a studio can spend hours per frame chasing perfection.
• There is no single right answer; the skill is matching the method to the budget.

9. Graphics is making images; vision and processing handle them differently.

Computer graphics is often confused with two neighboring fields. They all involve images, but they move in different directions. Knowing the difference clarifies what graphics actually does.

• Computer graphics: takes a description and produces an image. Numbers go in, a picture comes out.
• Computer vision: takes an image and extracts a description. A picture goes in, meaning comes out.
• Image processing: takes an image and produces a changed image, sharpening or filtering it.
• Graphics and vision are near-mirror images of one another, running in opposite directions.
• Modern AI tools increasingly blur all three lines, but the core distinction still clarifies.

10. Four things people get wrong about computer graphics.

Because graphics works best when it is invisible, most people carry a few mistaken beliefs about it. Naming them now prevents confusion in every class that follows.

• "Graphics is just for movies and games." It is foundational to science, medicine, and design too.
• "The computer creates the art." It executes a human's description; the artistry is in the model.
• "3D graphics is the only real graphics." Flat 2D graphics is older, vast, and everywhere on screens.
• "More expensive hardware automatically means better images." Algorithms and craft matter more.
• Most surprising graphics results follow from understanding it as math, not magic.

11. Graphics tools fall into a few clear families you can already name.

The world of graphics software can look chaotic, but it organizes neatly into a handful of families. Knowing the families lets you make sense of any tool you meet, and many of the best are free.

• 2D image and design tools: for painting, photo editing, and laying out flat artwork.
• 3D modeling and animation suites: for building, posing, and animating three-dimensional scenes.
• Renderers: the engines that take a 3D scene and compute the final image.
• Game engines: real-time toolkits bundling rendering, physics, and interaction together.
• Blender is a free, capable suite that spans modeling, animation, and rendering in one place.

12. Spend ten minutes naming the graphics hidden in plain sight around you.

You can sharpen your eye for this field in ten minutes, with no software at all. The goal is to start seeing the graphics work that is everywhere and usually invisible to you.

• Look at any screen and list five things on it that are computer graphics, not photographs.
• For each one, ask: was this mostly a 2D task or a 3D task?
• For each one, ask: did it need to be drawn instantly, or could it take hours to compute?
• Watch a few seconds of an animated film and try to spot one modeling choice a human made.
• Notice how quickly graphics stops feeling like magic once you name its pieces.

13. You can now see that nearly every screen is computer graphics at work.

Six things to carry out of class one.

• Computer graphics is the craft of creating and manipulating images with code and math.
• It exists to bridge a gap: computers store numbers, but humans understand pictures.
• It divides into two great halves: modeling, describing a scene, and rendering, computing the image.
• It is everywhere, in film and games but also in science, medicine, engineering, and design.
• One tension runs through it all: realism pulls against the time a computer takes to deliver it.
• Graphics is mathematics and craft, not magic, and the artistry lives in the human's choices.

Mastery quiz

1. Computer graphics is best defined as the craft of:
   • Photographing real scenes with digital cameras
   • Creating and manipulating images using code and mathematics
   • Storing numbers efficiently in computer memory
   • Interpreting the meaning of existing photographs
2. What are the four stages a piece of graphics work moves through, in order?
   • Transform, describe, shade, decide visibility
   • Describe, transform, decide visibility, shade
   • Render, model, light, photograph
   • Shade, transform, describe, decide visibility
3. The single unavoidable tension that governs nearly every graphics decision is:
   • Realism against the time it takes to compute
   • Two-dimensional against three-dimensional art
   • Hardware cost against software cost
   • Modeling against computer vision
4. Why does a video game sit at the opposite extreme from a film studio on that tension?
   • Games never use three-dimensional worlds
   • A game has only a few milliseconds per frame, so it must approximate
   • Films cannot use graphics chips
   • Games render each frame over several hours