Watermark

Stamp a text or logo watermark onto an image — at one of 9 anchor positions, or tiled across the whole image.

Function

add_watermark(input, &WatermarkOptions) -> Vec<u8>

Language	Name
Rust	add_watermark
JavaScript	addWatermark
Python	add_watermark
CLI	dusrelimage watermark <input> --text "© dusrel" -o out.jpg

Options

Field	Type	Default	Meaning
text	TextWatermark or null	null	Text stamp: text string, size (font size), colour.
logo	ImageWatermark or null	null	Logo stamp: image bytes, scale, opacity, position, margin.
opacity	f32	0.5	Overall opacity, 0–1. Outside 0–1 → INVALID_ARGUMENT.
position	Position	BottomRight	9 anchors or Tiled (see below).
rotation_deg	f32	0	Rotation in degrees, clockwise.
margin	u32	16	Distance from the edge, in pixels.

Give text, logo, or both — text is drawn first, then the logo. Giving neither is INVALID_ARGUMENT.

Positions

TopLeft, TopCenter, TopRight, CenterLeft, Center, CenterRight, BottomLeft, BottomCenter, BottomRight, or Tiled (repeat the watermark in a grid across the whole image — the usual anti-theft stamp for proofs).

Text is drawn with the bundled DejaVu Sans font (ab_glyph).

Examples

import { addWatermark } from 'dusrelimage';

// Text stamp, bottom right, semi-transparent
const out = addWatermark(input, {
  text: { text: '© dusrel', size: 36, colour: '#ffffff' },
  opacity: 0.5,
  position: 'BottomRight',
});

// Diagonal tiled stamp across the whole image
const proof = addWatermark(input, {
  text: { text: 'PROOF', size: 48, colour: '#ffffff' },
  opacity: 0.25,
  position: 'Tiled',
  rotationDeg: -30,
});

// Logo stamp, scaled to 20% of the image width
const branded = addWatermark(input, {
  logo: { image: logoBytes, scale: 0.2 },
  opacity: 0.8,
  position: 'BottomRight',
  margin: 24,
});

dusrelimage watermark photo.jpg --text "© dusrel" --opacity 0.5 -o marked.jpg
dusrelimage watermark photo.jpg --logo logo.png --position bottom-right -o marked.jpg

Errors

Code	When
INVALID_IMAGE	Input (or logo) is not a decodable image.
INVALID_ARGUMENT	Neither text nor logo given; opacity outside 0–1.
IMAGE_TOO_LARGE	Over max_pixels (default 120,000,000).
EMPTY_INPUT	Empty input bytes.