Alströmergymnasiet map

Maps

A map surface here is usually a stitched top-down image. Instead of loading one gigantic picture, it can be split into many small map tiles at several zoom levels.

That stack of tiles is called a tile pyramid: zoomed out uses a few low-detail tiles, zoomed in asks for the sharper pieces under your screen. It is how the page can zoom into big stitched images without making every visitor download the whole thing up front.

Tiled web maps · Tile Map Service

Photos

Photos are not just one resized JPEG. A good source can become AVIF, WebP, and JPEG fallbacks across several widths, with a tiny placeholder so the layout is stable before the real image arrives.

Some images also keep richer variants such as wide-gamut or deep-colour AVIF. Those stay separate from the everyday fallback path, because a phone screen, a desktop display, and an old browser do not deserve the same file.

AVIF · WebP

Why the variants exist

Browsers, screens, networks, and media types do not agree on one perfect file. The page stays simple, while the saved asset details keep source kind, quality level, preview confidence, dimensions, format, and fallback intent.

Each asset gets the special handling it needs. The goal is not to show off file formats; it is to make the page choose the right thing quietly, then explain the machinery only when you ask.