Presets

A preset is a named starting point: it sets quality, effort and subsampling defaults in one word. Any option you set explicitly always overrides the preset’s value for that field — a preset never locks you out of a control.

The four presets

Preset	Quality	Subsampling	Effort	Best for
Web	80	S420	4	Small files for web pages
Social	85	S420	4	Balanced quality for sharing
Print	95	S444	6	High quality for print
Archive	100	S444	6	Near-lossless keeping (lossless where the format supports it)

A preset sets only quality, effort and subsampling — it never touches progressive (default false) or any other field.

These numbers are the v0.1.0 contract (defined in shared/spec.md): the core implements exactly these values in every binding.

How to use them

dusimagez compress photo.jpg web.jpg --preset web
dusimagez compress photo.jpg social.jpg --preset social

use dusimagez::{compress_image, CompressOptions, Preset};

let mut options = CompressOptions::default();
options.preset = Some(Preset::Web);
let out = compress_image(&bytes, &options)?;

Overriding a preset

// Web preset, but keep full colour resolution
let mut options = CompressOptions::default();
options.preset = Some(Preset::Web);
options.subsampling = Subsampling::S444; // explicit field wins
let out = compress_image(&bytes, &options)?;

Which preset should I pick?

• Web — the default choice for images on a page. Quality 80 with S420 subsampling is where most of the size saving comes from.
• Social — a step up in quality for images people will look at closely (profile photos, shared albums). Still small.
• Print — quality 95 with full colour resolution (S444). For images that will be printed or zoomed, where artefacts would actually show.
• Archive — keep as much as possible. Quality 100, S444, and lossless where the output format supports it. The file will be much larger than Web — that is the point.

If none of these fits, skip the preset and set quality, subsampling and effort directly — see the Options reference.