README

node-jpeg-turbo

node-jpeg-turbo provides minimal libjpeg-turbo bindings for Node.js. It is very, very fast compared to other alternatives, such as node-imagemagick-native or jpeg-js.

Please ask if you need more methods exposed.

Requirements

We use NAN to guarantee maximum v8 API compatibility, so in theory any Node.js or io.js version should work fine. For maximum convenience we also use node-pre-gyp to publish prebuilt binaries for a few common platforms. For example, if you're on OS X and using the latest stable Node, you probably won't need to do a thing.

If you must build from source

First, if you're building from the repo, make sure to init and update submodules or you'll get confusing errors about missing targets when building. We include libjpeg-turbo as a submodule.

git submodule init
git submodule update

(or just use git clone --recursive when cloning the repo)

Due to massive linking pain on Ubuntu, we embed and build libjpeg-turbo directly with node-gyp. Unfortunately this adds an extra requirement, as the build process needs yasm to enable all optimizations. Note that this step is only required for x86 and x86_64 architectures. You don't need yasm if you're building on arm, for example.

Here's how to install yasm:

On OS X

brew install yasm

On Ubuntu 14.04

apt-get install yasm

On Ubuntu 12.04

apt-get install yasm

Important! Ubuntu 12.04 comes with GCC 4.6, which is too old to compile the add-on (and most other modules since Node.js 4.0 was released). More information is available here.

If you really must use this module on Ubuntu 12.04, the following may work:

apt-get install python-software-properties
add-apt-repository -y ppa:ubuntu-toolchain-r/test
apt-get -y install g++-4.8
export CXX=g++-4.8

Remember to export CXX when you npm install.

On Debian

apt-get install yasm

On Alpine Linux

apk add yasm

Others

Search your package manager for yasm.

Installation

Make sure you've got the requirements installed. Then simply install from NPM:

npm install --save jpeg-turbo

API

`jpg.bufferSize(options)` → `Number`

If you'd like to preallocate a Buffer for jpg.compressSync(), use this method to get the worst-case upper bound. The options argument is fully compatible with the jpg.compressSync() method, so that you can pass the same options to both functions.

options is an Object with the following properties:
- width Required. The width of the image.
- height Required. The height of the image.
- subsampling Optional. The subsampling method to use. Defaults to jpg.SAMP_420.
Returns The Number of bytes required in a worst-case scenario.

var fs = require('fs')
var jpg = require('jpeg-turbo')

var raw = fs.readFileSync('raw.rgba')

var options = {
  format: jpg.FORMAT_RGBA,
  width: 1080,
  height: 1920,
  subsampling: jpg.SAMP_444,
}

var preallocated = new Buffer(jpg.bufferSize(options))

var encoded = jpg.compressSync(raw, preallocated, options)

`jpg.compressSync(raw[, out], options)` → `Buffer`

Compresses (i.e. encodes) the raw pixel data into a JPG. This method is not capable of resizing the image.

For efficiency reasons you may choose to encode into a preallocated Buffer. While fast, it has a number of drawbacks. Namely, you'll have to be careful not to reuse the buffer in async processing before processing (e.g. saving, displaying or transmitting) the entire encoded image. Otherwise you risk corrupting the image. Also, it wastes a huge amount of space compared to on-demand allocation.

raw is a Buffer with the raw pixel data in options.format.
out is an optional preallocated Buffer for the encoded image. The size of the buffer is checked. See jpg.bufferSize() for an example of how to preallocate a sufficient Buffer. If not given, memory is allocated and reallocated as needed, which eliminates most of the wasted space but is slower and lacks consistency with varying source images.
options is an Object with the following properties:
- format Required. The format of the raw pixel data (e.g. jpg.FORMAT_RGBA).
- width Required. The width of the image.
- height Required. The height of the image.
- subsampling Optional. The subsampling method to use. Defaults to jpg.SAMP_420.
- quality Optional. The desired JPG quality. Defaults to 80.
Returns The encoded image as a Buffer. Note that the buffer may actually be a slice of the preallocated Buffer, if given. Be careful not to reuse the preallocated buffer before you've finished processing the encoded image, as it may corrupt the image.

var fs = require('fs')
var jpg = require('jpeg-turbo')

var raw = fs.readFileSync('raw.rgba')

var options = {
  format: jpg.FORMAT_RGBA,
  width: 1080,
  height: 1920,
  subsampling: jpg.SAMP_444,
}

var encoded = jpg.compressSync(raw, options)

See jpg.bufferSize() for an example of preallocated Buffer usage.

`jpg.decompressSync(image[, out], options)` → `Object`

Decompresses (i.e. decodes) the JPG image into raw pixel data.

image is a Buffer with the JPG image data.
out is an optional preallocated Buffer for the decoded image. The size of the buffer is checked, and should be at least width * height * bytes_per_pixel or larger. If not given, one is created for you. The only benefit of providing the Buffer yourself is that you can reuse the same buffer between multiple jpg.decompressSync() calls. Note that this can lead to issues with concurrency. See jpg.compressSync() for related discussion.
options is an Object with the following properties:
- format Required. The desired format of the raw pixel data (e.g. jpg.FORMAT_RGBA).
- out Deprecated. Use the out argument instead.
Returns An Object with the following properties:
- data A Buffer with the raw pixel data.
- width The width of the image.
- height The height of the image.
- subsampling The subsampling method used in the JPG.
- size Deprecated. Use data.length instead.
- bpp The number of bytes per pixel.

var fs = require('fs')
var jpg = require('jpeg-turbo')

var image = fs.readFileSync('image.jpg')

var options = {
  format: jpg.FORMAT_RGBA,
}

var decoded = jpg.decompressSync(image, options)

Thanks

License

See LICENSE.

Usage no npm install needed!