draft · v0.1.226
💬Comments welcome. To leave a note, select any text and click the note / highlight button that pops up — or open the panel with the tab at the top-right (‹). Notes are visible only inside our private review group.

2.0 FUNDAMENTALS of Imaging⧉

A photograph records light that has traveled from a source, interacted with a scene, and reached a sensor or eye. Light leaves a source, such as the sun, a lamp, or a phone screen, and travels until it strikes 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 labeled 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, and how it behaves when it meets a surface (the first chapter). Then we cross straight into the observer, because color is made there: the eye and visual system, why three cones make us trichromatic, and color as the projection of a whole spectrum onto three numbers, together with its engineering payoff, color technology (measuring color with the CIE system, encoding it in linear / gamma / log, and reproducing it). Only then do we 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, such as perspective, focus, and depth of field, and how a pixel value is an integral of the incoming light, and the sensor and the noise that floor what we can see. Those threads converge in the two abstract chapters that frame the whole book: imaging as a linear system and imaging as an inverse problem. The part closes by stepping back to the medium itself and asking what a picture fundamentally cannot do: its limitations against the eye: flatness, a frozen instant, a finite frame, and limited dynamic range and gamut. The craft of a real camera as an instrument, and the question of why a photograph is never a neutral recording, follow in the next part, Photography.

Contents of this part

▸ full collapsible outline of this part