# jpeg-js A pure javascript JPEG encoder and decoder for node.js **NOTE:** this is a _synchronous_ (i.e. CPU-blocking) library that is much slower than native alternatives. If you don't need a _pure javascript_ implementation, consider using async alternatives like [sharp](http://npmjs.com/package/sharp) in node or the [Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API) in the browser. [![build status](https://secure.travis-ci.org/eugeneware/jpeg-js.png)](http://travis-ci.org/eugeneware/jpeg-js) ## Installation This module is installed via npm: ```bash $ npm install jpeg-js ``` ## Example Usage ### Decoding JPEGs Will decode a buffer or typed array into a `Buffer`; ```js var jpeg = require('jpeg-js'); var jpegData = fs.readFileSync('grumpycat.jpg'); var rawImageData = jpeg.decode(jpegData); console.log(rawImageData); /* { width: 320, height: 180, data: } */ ``` To decode directly into a `Uint8Array`, pass `useTArray: true` in options `decode`: ```js var jpeg = require('jpeg-js'); var jpegData = fs.readFileSync('grumpycat.jpg'); var rawImageData = jpeg.decode(jpegData, {useTArray: true}); // return as Uint8Array console.log(rawImageData); /* { width: 320, height: 180, data: { '0': 91, '1': 64, ... } } // typed array */ ``` #### Decode Options | Option | Description | Default | | -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- | | `colorTransform` | Transform alternate colorspaces like YCbCr. `undefined` means respect the default behavior encoded in metadata. | `undefined` | | `useTArray` | Decode pixels into a typed `Uint8Array` instead of a `Buffer`. | `false` | | `formatAsRGBA` | Decode pixels into RGBA vs. RGB. | `true` | | `tolerantDecoding` | Be more tolerant when encountering technically invalid JPEGs. | `true` | | `maxResolutionInMP` | The maximum resolution image that `jpeg-js` should attempt to decode in megapixels. Images larger than this resolution will throw an error instead of decoding. | `100` | | `maxMemoryUsageInMB` | The (approximate) maximum memory that `jpeg-js` should allocate while attempting to decode the image in mebibyte. Images requiring more memory than this will throw an error instead of decoding. | `512` | ### Encoding JPEGs ```js var jpeg = require('jpeg-js'); var width = 320, height = 180; var frameData = new Buffer(width * height * 4); var i = 0; while (i < frameData.length) { frameData[i++] = 0xff; // red frameData[i++] = 0x00; // green frameData[i++] = 0x00; // blue frameData[i++] = 0xff; // alpha - ignored in JPEGs } var rawImageData = { data: frameData, width: width, height: height, }; var jpegImageData = jpeg.encode(rawImageData, 50); console.log(jpegImageData); /* { width: 320, height: 180, data: } */ // write to file fs.writeFileSync('image.jpg', jpegImageData.data); ``` ## License ### Decoding This library builds on the work of two other JPEG javascript libraries, namely [jpgjs](https://github.com/notmasteryet/jpgjs) for the decoding which is licensed under the Apache 2.0 License below: Copyright 2011 notmasteryet Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at [http://www.apache.org/licenses/LICENSE-2.0](http://www.apache.org/licenses/LICENSE-2.0) Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ### Encoding The encoding is based off a port of the JPEG encoder in [as3corelib](https://code.google.com/p/as3corelib/source/browse/trunk/src/com/adobe/images/JPGEncoder.as). The port to Javascript was done by by Andreas Ritter, www.bytestrom.eu, 11/2009. The Adobe License for the encoder is: **Adobe** Copyright (c) 2008, Adobe Systems Incorporated All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name of Adobe Systems Incorporated nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ## Contributing jpeg-js is an **OPEN Open Source Project**. This means that: > Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project. See the [CONTRIBUTING.md](https://github.com/eugeneware/jpeg-js/blob/master/CONTRIBUTING.md) file for more details. ### Contributors jpeg-js is only possible due to the excellent work of the following contributors:

Adobe	GitHub/adobe
Yury Delendik	GitHub/notmasteryet
Eugene Ware	GitHub/eugeneware
Michael Kelly	GitHub/mrkelly
Peter Liljenberg	GitHub/petli
XadillaX	GitHub/XadillaX
strandedcity	GitHub/strandedcity
wmossman	GitHub/wmossman
Patrick Hulce	GitHub/patrickhulce
Ben Wiley	GitHub/benwiley4000

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zip	lib/	62713	2	---	2025-10-15 10:09:41
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-	LICENSE	1448		%	2025-10-15 10:08:12
-	README.md	8418		md	2025-10-15 10:08:12
-	index.d.ts	996		ts	2025-10-15 10:08:12
-	index.js	136		js	2025-10-15 10:08:12
-	package.json	643		json	2025-10-15 10:08:12

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