2.0 FUNDAMENTALS of Photography⧉

Every photograph is the end of a journey. Light leaves a source — the sun, a lamp, a phone screen — travels until it strikes the objects in a scene, scatters according to what those objects are made of, and a sliver of it finally passes through a lens onto a sensor (or, in the eye, onto the retina). The sensor counts photons; the camera turns those counts into a grid of numbers; a visual system, silicon or biological, interprets the result (Figure 2.0.1). Photography means, almost literally, writing with light — from the Greek phōs ("light") and graphē ("drawing").

fig-light-journey — **Figure 2.0.1.** The journey of light, and the chapters that follow it. A source emits light → it strikes objects and is reflected, absorbed, and scattered (the scene) → it passes through a lens → it lands on a sensor or the retina → and a visual system interprets it. Each step is labelled with the chapter that covers it.

This part follows that journey, because every later trick in the book depends on it. We begin with light itself — what it is (wave, ray, or photon), how it carries color, how it behaves when it meets a surface, and how we measure it (the first chapter). We then ask how a camera turns the light filling a room into a flat picture: the geometry of image formation, from the pinhole to the lens and the limits geometry imposes — perspective, focus, depth of field — and the sensor and the noise that floors what we can see. From there we cross into the observer: the eye and visual system, why three cones make us trichromatic, and color as the projection of a whole spectrum onto three numbers. The engineering payoff is color technology — measuring color (CIE), encoding it (linear, gamma, log), and reproducing it. Only then do we sit behind a real camera as an instrument — the exposure controls and modes, autofocus, stabilization, and the hardware of how a photograph is actually taken (from a mirrorless body to a phone). The part closes with human factors and the art of photography — composition, light, and the ethics of the medium.

None of this is computational yet. It is the physical and perceptual stage on which computation will later act — and it is where most of a photographer's craft lives, and where the rest of the book gets its vocabulary. A reader who only wants to code can skip ahead to BASIC IMAGE PROCESSING, but the part's big lessons recur on every later page: that much of imaging is multiplicative (illumination × albedo) while some is additive, so the right encoding follows from which one you are doing; that perception is roughly logarithmic, so ratios matter more than absolute values; that noise is read plus shot, worst in the shadows; that perspective is a matrix and a divide-by-depth; and that color is non-orthogonal and non-negative, which is what makes it genuinely hard. By the end of the part you can trace a photon from a lamp to a perceived color, and you carry the small set of principles the book keeps reusing.

Contents of this part

▸ full collapsible outline of this part

2.0 FUNDAMENTALS of Photography🔗⧉

Contents of this part

2.0 FUNDAMENTALS of Photography⧉