# fast-bmp

> A BMP image decoder and encoder

Latest version **4.0.1** (published 2025-08-13) · MIT license · 0 weekly downloads

## Install

```sh
npm install fast-bmp
pnpm add fast-bmp
yarn add fast-bmp
bun add fast-bmp
```

## Health

**Score 30/100 (F)** — status: maintenance-mode.

Positive: esm support; no vulnerabilities.

Warnings: low downloads; no types.

Negative: stale; low maintenance score.

## Facts

| | |
|---|---|
| Version | 4.0.1 |
| Published | 2025-08-13 |
| First published | 2016-12-14 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | ESM |
| Dependencies | 1 |
| Unpacked size | 51.3 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 8 |
| Author | Daniel Kostro |
| Maintainers | lpatiny, stropitek, targos, cheminfo-bot |

## Links

- npm: https://www.npmjs.com/package/fast-bmp
- Repository: https://github.com/image-js/fast-bmp
- Homepage: https://image-js.github.io/fast-bmp/
- Issues: https://github.com/image-js/fast-bmp/issues
- npm.io page: https://npm.io/package/fast-bmp

## Dependencies (1)

- [iobuffer](https://npm.io/package/iobuffer.md) ^6.0.0

## Recent versions

- 4.0.1 (latest) — 2025-08-13
- 4.0.0 — 2025-06-15
- 3.0.0 — 2025-04-15
- 2.0.1 — 2022-09-29
- 2.0.0 — 2022-07-31
- 1.0.2 — 2022-07-31
- 1.0.1 — 2022-07-29
- 1.0.0 — 2016-12-15
- 0.0.1 — 2016-12-14

## README

<h3 align="center">
  <a href="https://www.zakodium.com">
    <img src="https://www.zakodium.com/brand/zakodium-logo-white.svg" width="50" alt="Zakodium logo" />
  </a>
  <p>
    Maintained by <a href="https://www.zakodium.com">Zakodium</a>
  </p>
</h3>

# fast-bmp

[![NPM version](https://img.shields.io/npm/v/fast-bmp.svg)](https://www.npmjs.com/package/fast-bmp)
[![npm download](https://img.shields.io/npm/dm/fast-bmp.svg)](https://www.npmjs.com/package/fast-bmp)
[![test coverage](https://img.shields.io/codecov/c/github/image-js/fast-bmp.svg)](https://codecov.io/gh/image-js/fast-bmp)
[![license](https://img.shields.io/npm/l/fast-bmp.svg)](https://github.com/image-js/fast-bmp/blob/main/LICENSE)

A BMP image decoder and encoder.

## Installation

```console
npm install fast-bmp
```

## API

### [Complete API documentation](https://image-js.github.io/fast-bmp/)

### Supported features

This library only supports V5 headers.

- binary (1-bit per pixel)
- greyscale (8-bits per pixel)
- RGB (24-bits per pixel)
- RGBA (32-bits per pixel)

### Encoding

```js
import { encode } from 'fast-bmp';

// 0 0 0 0 0
// 0 1 1 1 0
// 0 1 0 1 0
// 0 1 1 1 0
// 0 0 0 0 0
const data = new Uint8Array([
  0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0,
]);
const imageData = {
  width: 5,
  height: 5,
  data,
  bitsPerPixel: 1,
  components: 1,
  channels: 1,
};
// Encode returns a Uint8Array.
const encoded = encode(imageData);
fs.writeFileSync('image.bmp', encoded);
```

### Decoding

```ts
import { decode } from 'fast-bmp';

// 0 0 0 0 0
// 0 1 1 1 0
// 0 1 0 1 0
// 0 1 1 1 0
// 0 0 0 0 0
const buffer = fs.writeFileSync('image.bmp');
const imageData = decode(buffer);
/* Returns object:
{
width: 5,
height: 5,
data: new Uint8Array([
    0, 0, 0, 0, 0, 
    0, 1, 1, 1, 0, 
    0, 1, 0, 1, 0, 
    0, 1, 1, 1, 0, 
    0, 0, 0, 0, 0,
  ]),
bitsPerPixel: 1,
components: 1,
channels: 1,
colorMasks: [0x00ff0000, 0x0000ff00, 0x000000ff],
compression: 0,
xPixelsPerMeter: 2835,
yPixelsPerMeter: 2835,
}
*/
```

## References

- [Wikipedia BMP format page](https://en.wikipedia.org/wiki/BMP_file_format)
- [Microsoft BMPV5 format page](https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapv5header)

## License

[MIT](./LICENSE)

---
_Source: https://npm.io/package/fast-bmp · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._