Why Is It Like This?
The original sins of computer graphics.
Every industry has its haunted houses — the defaults nobody set, the numbers everyone uses, the conventions that made sense once and now just live here. Here’s the tour.
[Section intro: what the anthology is. One growing page, anchor-linked entries, stable per-sin URLs for deep-linking. Voice: dry, mildly outraged, affectionate. Each entry is a tiny historical whodunit. Per-entry format decided as each is written.]
Signal bleed
[The showpiece, and the anchor for the broadcast cluster. Real signals are leaky and real hardware is non-ideal — which is why standards have guard bands, why broadcast levels have footroom and headroom, why frame rates were tied to the grid. All the “stupid” defaults trace back here.]
The guard band is the whole story in one idea: leave room, because nothing is as clean as the spec.
Frequency axis with allocated bands marked. A signal-strength slider; as strength rises, the signal’s skirt widens and bleeds into the neighboring band. The aha that anchors frame rates, broadcast levels, and more.
The Utah teapot
[Pixel aspect ratio. Punchline: Martin Newell’s actual teapot at the Computer History Museum is squashed too — the canonical CG reference object of all time has been wrong since 1975.]
Blame pixel aspect ratio: the pixels were never square.
Rotating teapot point cloud with a pixel-aspect-ratio slider (1.0, 0.9 NTSC D1 4:3, 1.067 NTSC widescreen). Watch the teapot deform.
Broadcast levels (16–235)
[Why “legal” range exists. Possibly absorbed into the spectrum widget rather than standing alone.]
Waveform-monitor view with the legal range shaded and danger zones marked. A brightness slider pushes values into the danger zone.
Overscan & title-safe
[That invisible margin in every NLE is older than HDTV.]
Overscan is gone; the margins it forced on us never left.
A 16:9 frame with content. Toggle CRT overscan on (a vignette eats the outer 5%, the title is half-cropped); toggle the title-safe guide on to see why it’s there.
Interlacing
[“30fps” video was never 30 coherent frames per second — half the picture was sent every 1/60 second.]
Interlacing is why your “30fps” footage combs the moment anything moves.
A 60i clip showing comb artifacts on a moving subject when played progressively; a deinterlace toggle smooths it.
Drop-frame timecode
[Drop-frame isn’t losing frames, it’s renumbering them so timecode-as-time matches reality.]
Drop-frame drops numbers, never frames — the most-misunderstood word in post.
A real-time timecode counter with a toggle against the wall clock; drop-frame skips “:00” and “:01” at minute boundaries (except every tenth minute).
sRGB ≠ gamma 2.2
[Everyone’s been doing it slightly wrong, but the wrongness is small enough nobody notices — except in the deep shadows where it matters most.]
sRGB and gamma 2.2 on the same axes; toggle the difference to reveal the tiny linear toe in the shadows.
Kelvin is backwards
[Pure counterintuitive labeling, large aha.]
A color swatch tied to a Kelvin slider. Drag down (2700K) → warm / orange; drag up (10000K) → cool / blue.
The prose queue
[Prose-only entries, no widget required. Write the ones that make me mad; abandon the rest. Stable anchors get added per entry as they’re written.]
- 29.97 / 23.98 origin story (the NTSC color-subcarrier kludge — the best “why is this number cursed” story)
- 24fps origin (sound-on-film economics)
- 2-3 pulldown
- 48k vs 44.1k (video vs music audio)
- 0.5 pixel-center offset
- Powers-of-two textures
- 18% / middle gray (photographic light-meter inheritance)
[The page is whatever survives. Do not pressure-finish entries.]
Glossary
Every term used in this guide, defined once. In the prose, underlined-dotted terms show their short definition on hover or focus, and jump here on click.
- Guard band
- Deliberately unused frequency range left between allocated bands so that leaky, non-ideal real-world signals don’t bleed into their neighbors. The reason half these "stupid" defaults exist.
- Pixel aspect ratio
- The ratio of a pixel’s width to its height. SD video pixels weren’t square (0.9, 1.067…), which is why old footage and even the canonical Utah teapot look squashed if you assume 1.0.
- Overscan
- Old TVs cropped the outer ~5% of the picture. Title-safe and action-safe margins — still in every NLE — exist to survive that crop, long after CRTs are gone.
- Interlacing
- Sending every other scanline each field, 60 times a second, instead of whole frames 30 times. "30fps" interlaced video was never 30 coherent frames per second.
- Drop-frame
- A timecode scheme that skips certain frame numbers (not actual frames) so that 29.97fps timecode stays aligned with real wall-clock time.