ts-bmp

A pure TypeScript BMP encoder and decoder with zero dependencies.

Features

• 🚀 Pure TypeScript - no native dependencies
• 📦 Zero dependencies
• 🎨 Supports multiple bit depths: 1, 4, 8, 16, 24, 32 bits
• 🗜️ RLE compression support (RLE4 and RLE8)
• 🔄 Encode and decode BMP images
• 📐 Handles both bottom-up and top-down BMPs

Installation

bun add ts-bmp
# or
npm install ts-bmp

Usage

Decoding

import { decode } from 'ts-bmp'

const buffer = await Bun.file('image.bmp').arrayBuffer()
const { data, width, height } = decode(new Uint8Array(buffer))

// data is RGBA pixel data (4 bytes per pixel)
console.log(`Image size: ${width}x${height}`)

Encoding

import { encode } from 'ts-bmp'

const imageData = {
  data: new Uint8Array(width * height * 4), // RGBA pixel data
  width: 100,
  height: 100,
}

// Encode as 32-bit BMP (with alpha channel)
const bmpBuffer = encode(imageData, { bitsPerPixel: 32 })
await Bun.write('output.bmp', bmpBuffer)

// Or encode as 24-bit BMP (no alpha)
const bmp24 = encode(imageData, { bitsPerPixel: 24 })

API

decode(buffer: Uint8Array): BmpImageData

Decodes a BMP image buffer to RGBA pixel data.

Returns:

• data: Uint8Array - RGBA pixel data (4 bytes per pixel)
• width: number - Image width in pixels
• height: number - Image height in pixels

encode(imageData: BmpImageData, options?: BmpEncodeOptions): Uint8Array

Encodes RGBA pixel data to BMP format.

Options:

• bitsPerPixel: 24 | 32 - Bits per pixel (default: 32)

Supported Formats

Decoding

• 1-bit monochrome
• 4-bit indexed (with RLE4 compression)
• 8-bit indexed (with RLE8 compression)
• 16-bit RGB (with bit field support)
• 24-bit RGB
• 32-bit RGBA

Encoding

• 24-bit RGB
• 32-bit RGBA (with alpha channel support)

License

MIT