Node JPEG

Prerequisites

• CMake >= 3.21.0

Installation

npm install giovannicalo/node-jpeg

Not yet published to NPM. This will install it from GitHub.

Usage

Decoding

const { promises: { readFile, writeFile } } = require("fs");

const { Format, decode } = require("jpeg");

(async () => {
    const jpeg = await readFile("foo.jpg");
    const rgba = await decode(jpeg, Format.rgba);
    console.log(rgba);
    // {
    //   data: Uint8ClampedArray(8294400) [...],
    //   format: 0,
    //   height: 1080,
    //   width: 1920
    // }
    await writeFile("foo.rgba", rgba.data);
    const yuv = await decode(jpeg, Format.yuv);
    console.log(yuv);
    // {
    //   data: Uint8ClampedArray(3110400) [...],
    //   format: 1,
    //   height: 1080,
    //   width: 1920
    // }
    await writeFile("foo.yuv", yuv.data);
})();

Encoding

const { promises: { readFile, writeFile } } = require("fs");

const { Format, encode } = require("jpeg");

(async () => {
    const rgba = {
        data: await readFile("foo.rgba"),
        format: Format.rgba,
        height: 1080,
        width: 1920
    };
    const rgbaJpeg = await encode(rgba, 90);
    console.log(rgbaJpeg);
    // <Buffer ...>
    await writeFile("foo.jpg", rgbaJpeg);
    const yuv = {
        data: await readFile("foo.yuv"),
        format: Format.yuv,
        height: 1080,
        width: 1920
    };
    const yuvJpeg = await encode(yuv, 90);
    console.log(yuvJpeg);
    // <Buffer ...>
    await writeFile("bar.jpg", yuvJpeg);
})();

API

Format.rgba = 0

Standard RGBA format.

Format.yuv = 1

YUV I420 format. Smaller and faster than RGBA, but less straightforward. When decoding, if the source JPEG has odd dimensions, they will be rounded up to the nearest even number. Currently, decoding only works if the JPEG already has YUV colorspace and 4:2:0 subsampling.

decode(data: Buffer, format: Format = Format.rgba): Promise<Image>

Decodes the JPEG image stored in the data Buffer as format, which can be either Format.rgba or Format.yuv.

Returns a promise resolving to an object with data, height, format and width properties.

encode(image: Image, quality: number = 90): Promise<Buffer>

Encodes a raw image as JPEG with the given quality. image must be an object with data, height, format and width properties.

Returns a promise resolving to a Buffer.