!@thi.ng/imago

!npm downloads

> [!NOTE]
> This is one of 214 standalone projects, maintained as part
> of the @thi.ng/umbrella monorepo
> and anti-framework.
>
> 🚀 Please help me to work full-time on these projects by sponsoring me on
> GitHub. Thank you! ❤️

- About
- Basic example
- Supported operations
- blur
- composite
- Common options
- Bitmap image layers
- Color layers
- Raw bitmap layers
- SVG layers
- Text layers
- crop
- dither
- exif
- extend
- gamma
- grayscale
- hsbl
- icc
- maxsize
- nest
- output
- Templated output paths
- resize
- rotate
- Status
- Positions & sizes
- Gravity
- Metadata handling
- Installation
- Dependencies
- API
- Multistage processing pipeline
- Authors
- License

About

JSON & API-based declarative and extensible image processing trees/pipelines.

Spiritual successor of an eponymous, yet never fully published
CLojure/Java-based image processor from 2014...

In this new TypeScript version all image I/O and processing is delegated to
sharp and
@thi.ng/pixel.

$3

Transformation trees/pipelines are simple JSON objects (but can be
programmatically created):

The following pipeline performs these steps (in sequence):

- auto-rotate image (using EXIF orientation info, if available)
- add 5% white border (size relative to shortest side)
- proportionally resize image to 1920px (longest side by default)
- overlay bitmap logo layer, positioned at 45% left / 5% bottom
- add custom EXIF metadata
- output this current stage as high quality AVIF (and record expanded output
path)
- crop center square region
- output as JPEG thumbnail (and record in outputs)
- compute
blurhash
(and record in outputs)

``json tangle:export/readme-example1.json
[
{ "op": "rotate" },
{ "op": "extend", "border": 5, "unit": "%", "ref": "min", "bg": "#fff" },
{ "op": "resize", "size": 1920 },
{
"op": "composite",
"layers": [
{
"type": "img",
"path": "logo-128.png",
"pos": { "l": 45, "b": 5 },
"unit": "%",
"blend": "screen"
}
]
},
{
"op": "exif",
"tags": {
"IFD0": {
"Copyright": "Karsten Schmidt",
"Software": "@thi.ng/imago"
}
}
},
{
"op": "output",
"id": "hires",
"path": "{name}-{sha256}-{w}x{h}.avif",
"avif": { "quality": 80 }
},
{ "op": "crop", "size": [240, 240], "gravity": "c" },
{ "op": "output", "id": "thumb", "path": "{name}-thumb.jpg" },
{ "op": "output", "id": "hash", "blurhash": 4 }
]
`

Then to process an image using above JSON spec (there're also API wrappers to
create these operator specs programmatically):

`ts tangle:export/readme1.ts
import { processImage } from "@thi.ng/imago";
import { readJSON } from "@thi.ng/file-io";

await processImage(
"test.jpg",
readJSON("readme-example1.json"),
{ outDir: "." }
);
`

Supported operations

TODO write docs

$3

Gaussian blur

- radius

$3

Compositing multiple layers. The following layer types are available, and custom
layer types can be registered via the polymorphic
defLayer()
function.

#### Common options

- blend mode
- position & origin
- gravity
- tiled repetition

#### Bitmap image layers

- resizable

#### Color layers

- size
- fill color (w/ alpha)

#### Raw bitmap layers

- from typed array or buffer

#### SVG layers

- from file or inline doc

#### Text layers

- optional background color (alpha supported)
- text color
- horizontal/vertical text align
- font family & size
- constrained to text box

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Cropping a part of the image

- from edges, defined region or size & aspect ratio only
- supports px or percent units
- proportional to a given reference side/size

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Supported dither modes from
thi.ng/pixel-dither:

- "atkinson"
- "burkes"
- "column"
- "diffusion"
- "floyd"
- "jarvis"
- "row"
- "sierra"
- "stucki"

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Set custom EXIF metadata (can be given multiple times, will be merged)

$3

Add pixels on all sides of the image

- supports px or percent units
- proportional to a given reference side/size
- can be individually configured per side

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Perform gamma correction (forward or reverse)

$3

Grayscale conversion

$3

Hue, saturation, brightness and lightness adjustments

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Assign ICC profile (from preset: p3, srgb, cmyk or from file). Can only be
given directly prior to output, overrides input ICC (if any) and only
used if output format actually supports it.

$3

Conditional version of resize operator, only applied if one of the
sides exceeds the configured size limit.

$3

Performing nested branches/pipelines of operations with no effect on image state
of current/parent pipeline...

$3

File output in any of these formats:

- avif
- gif
- jpeg
- jp2 (JPEG 2000)
- jxl (JPEG XL)
- png
- raw (headless raw data)
- tiff
- webp

Alternatively, a
blurhash of
the image can be computed and stored in the outputs. In this case, no file will
be written.

For all other formats, if no output path is provided in the spec, no file will
be written, but the encoded image buffer itself will be recorded in the outputs.
Use the raw output option to obtain the raw pixel data (number of channels
used will depend on previous operations).

`js
import { processImage, output } from "@thi.ng/imago";

const result = await processImage(
"example.png",
[output({id: "main", raw: { alpha: false } })]
);

// raw pixel data buffer
result.outputs.main
//
`

#### Templated output paths

Output paths can contain {id}-templated parts which will be replaced/expanded.
The following built-in IDs are supported and custom IDs will be looked up via
the
pathParts
options provided to
processImage().
Any others will remain as is. Custom IDs take precedence over built-in ones.

- name: original base filename (w/o ext)
- sha1/sha224/sha256/sha384/sha512: truncated hash of output (8 chars)
- w: current image width
- h: current image height
- aspect: "p" (portrait), "l" (landscape) or "sq" (square)
- date: yyyyMMdd date format, e.g. 20240223
- time: HHmmss time format, e.g. 234459
- year: 4-digit year
- month: 2-digit month
- week: 2-digit week
- day: 2-digit day in month
- hour: 2-digit hour (24h system)
- minute: 2-digit minute
- second: 2-digit second

Output paths can contain sub-directories which will be automatically created
(relative to the configured output
dir).
For example, the path template {year}/{month}/{day}/{name}-{sha1}.jpg might
get replaced to: 2024/02/22/test-123cafe4.jpg...

$3

Resizing image

- gravity or position
- fit modes
- supports px or percent units
- proportional to a given reference side/size

$3

Auto-rotate, rotate by angle and/or flip image along x/y

Status

ALPHA - bleeding edge / work-in-progress

Search or submit any issues for this package

Positions & sizes

Border sizes, general dimensions, and positions can be specified in pixels
(default) or as percentages (using unit: "%"). For the latter case, an
additional reference side (ref option) can be provided. The default ref is
min, referring to whatever is the smaller side of an image.

The ref option/reference side can take the following values (default: both):

- both: image width for horizontal uses, image height for vertical uses
- min: smaller side of an image (aka min(width,height))
- max: larger side of an image (aka min(width,height))
- w: image width
- h: image height

$3

In some operations positioning or alignment can be abstractly stated via one of
the following gravity values:

!diagram of the 9 possible gravity directions

Metadata handling

By default all input metadata will be lost in the outputs. The keepEXIF and
keepICC options can be used to retain EXIF and/or ICC profile information
(only if also supported in the output format).

Important: Retaining EXIF and merging it with custom additions is
still WIP...

Installation

`bash
yarn add @thi.ng/imago
`

ESM import:

`ts
import * as imago from "@thi.ng/imago";
`

For Node.js REPL:

`js
const imago = await import("@thi.ng/imago");
`

Package sizes (brotli'd, pre-treeshake): ESM: 5.31 KB

Dependencies

- @thi.ng/api
- @thi.ng/blurhash
- @thi.ng/checks
- @thi.ng/date
- @thi.ng/defmulti
- @thi.ng/errors
- @thi.ng/file-io
- @thi.ng/logger
- @thi.ng/object-utils
- @thi.ng/pixel
- @thi.ng/pixel-dither
- @thi.ng/prefixes
- sharp

Note: @thi.ng/api is in _most_ cases a type-only import (not used at runtime)

API

Generated API docs

$3

`ts tangle:export/readme-api.ts
import {
colorLayer,
composite,
crop,
extend,
imageLayer,
nest,
output,
processImage,
rawLayer,
resize,
rotate,
} from "@thi.ng/imago";
import { ConsoleLogger } from "@thi.ng/logger";

const res = await processImage(
"test.jpg",
// operator pipeline (i.e. a nested array of operator spec objects)
// the functions used here are merely syntax sugar for generating
// the spec objects to provide an anchor point for docs
// (ongoing effort, but since still a new project, mostly still forthcoming...)
[
// auto-rotate (EXIF orientation)
rotate({}),
// composite w/ semi-transparent color layer (screen)
composite({
layers: [
colorLayer({
// magenta with 50% opacity
bg: "#f0f8",
blend: "screen",
// layer size is 50x100% of image
size: [50, 100],
// aligned left (west)
gravity: "w",
// size given in percent
unit: "%",
}),
// diagonal hairline pattern overlay (with tiling) from raw
// pixel data in ABGR format, i.e. 0xAABBGGRR
rawLayer({
// prettier-ignore
buffer: new Uint32Array([
0x00000000, 0x00000000, 0x00000000, 0x80ffffff,
0x00000000, 0x00000000, 0x80ffffff, 0x00000000,
0x00000000, 0x80ffffff, 0x00000000, 0x00000000,
0x80ffffff, 0x00000000, 0x00000000, 0x00000000,
]),
channels: 4,
size: [4, 4],
tile: true,
}),
],
}),
// nested operations each operate on a clone of the current (already
// semi-transformed) image, they have no impact on the processing pipeline
// of their parent(s)
// multiple child pipelines can be spawned, here only a single one
nest({
procs: [
// this pipeline only creates blurhash (stored in outputs of result)
[resize({ size: 100 }), output({ id: "hash", blurhash: true })],
],
}),
// crop to 3:2 aspect ratio (always based on longest side)
crop({ size: 100, aspect: 3 / 2, unit: "%" }),
// back in the main pipleline, add 5% white border (based on smallest side)
extend({ border: 5, unit: "%", bg: "white", ref: "min" }),
// resize image to 1920 (largest side)
resize({ size: 1920 }),
// add logo watermark centered horizontally and near the bottom
composite({
layers: [
imageLayer({
path: "logo-128.png",
unit: "%",
origin: "s",
pos: { l: 50, b: 5 },
ref: "both",
blend: "screen",
}),
],
}),
output({ id: "main", path: "{date}-1920-frame.jpg" }),
],
{
logger: new ConsoleLogger("img"),
}
);

console.log(res.outputs);
// {
// hash: "UVKmR.^SIVR$_NRiM{jupLRjjEWC%goxofoM",
// main: "...../20240301-144948-1920-frame.jpg",
// }
`

Authors

- Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

`bibtex
@misc{thing-imago,
title = "@thi.ng/imago",
author = "Karsten Schmidt",
note = "https://thi.ng/imago",
year = 2024
}
``

License

© 2024 - 2026 Karsten Schmidt // Apache License 2.0