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https://github.com/tayloraswift/jpeg

decode, inspect, edit, and encode jpeg images in pure swift
https://github.com/tayloraswift/jpeg

codec jpeg multimedia-codecs pure-swift swift

Last synced: 16 days ago
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decode, inspect, edit, and encode jpeg images in pure swift

Host: GitHub
URL: https://github.com/tayloraswift/jpeg
Owner: tayloraswift
License: mpl-2.0
Created: 2017-11-06T07:38:33.000Z (about 7 years ago)
Default Branch: master
Last Pushed: 2024-04-18T19:25:58.000Z (7 months ago)
Last Synced: 2024-04-26T19:00:22.866Z (7 months ago)
Topics: codec, jpeg, multimedia-codecs, pure-swift, swift
Language: Swift
Homepage: https://kelvin13.github.io/jpeg/
Size: 63.9 MB
Stars: 140
Watchers: 6
Forks: 17
Open Issues: 3
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

README

        # jpeg

[![platforms](https://img.shields.io/badge/platforms-linux%20%7C%20macos-lightgrey.svg)](https://swift.org)

[![releases](https://img.shields.io/github/v/release/kelvin13/jpeg)](https://github.com/kelvin13/jpeg/releases)

[![build](https://img.shields.io/github/workflow/status/kelvin13/jpeg/build/master)](https://github.com/kelvin13/jpeg/actions?query=workflow%3Abuild)

[![build documentation](https://img.shields.io/github/workflow/status/kelvin13/jpeg/documentation/master?label=build%20docs)](https://github.com/kelvin13/jpeg/actions?query=workflow%3Adocumentation)

[![issues](https://img.shields.io/github/issues/kelvin13/jpeg)](https://github.com/kelvin13/jpeg/issues?state=open)

[![language](https://img.shields.io/badge/version-swift_5.5-ffa020.svg)](https://swift.org)

[![license](https://img.shields.io/badge/license-MPL2-ff3079.svg)](https://github.com/kelvin13/jpeg/blob/master/LICENSE)

Swift *JPEG* is a cross-platform pure Swift framework for decoding, inspecting, editing, and encoding JPEG images. The core framework has no external dependencies, including *Foundation*, and should compile and provide consistent behavior on *all* Swift platforms. The framework supports additional features, such as file system support, on Linux and MacOS. 

Swift *JPEG* is available under the [Mozilla Public License 2.0](https://www.mozilla.org/en-US/MPL/2.0/). The [example programs](examples/) are public domain and can be adapted freely.

## [tutorials and example programs](examples/)

* [basic decoding](examples#basic-decoding) ([sources](decode-basic/))

* [basic encoding](examples#basic-encoding) ([sources](encode-basic/))

* [advanced decoding](examples#advanced-decoding) ([sources](decode-advanced/))

* [advanced encoding](examples#advanced-encoding) ([sources](encode-advanced/))

* [using in-memory images](examples#using-in-memory-images) ([sources](in-memory/))

* [online decoding](examples#online-decoding) ([sources](decode-online/))

* [requantizing images](examples#requantizing-images) ([sources](recompress/))

* [lossless rotations](examples#lossless-rotations) ([sources](rotate/))

* [custom color formats](examples#custom-color-formats) ([sources](custom-color/))

## [api reference](https://kelvin13.github.io/jpeg/)

* [`JPEG.JPEG`](https://kelvin13.github.io/jpeg/JPEG/)

* [`JPEG.General`](https://kelvin13.github.io/jpeg/General/)

* [`JPEG.System`](https://kelvin13.github.io/jpeg/System/)

## getting started 

To Swift *JPEG* in a project, add this descriptor to the `dependencies` list in your `Package.swift`:

```swift 

.package(url: "https://github.com/kelvin13/jpeg", .exact("1.0.0")) 

```

## basic usage

Decode an image:

```swift 

import JPEG

func decode(jpeg path:String) throws

{

    guard let image:JPEG.Data.Rectangular = try .decompress(path: path)

    else 

    {

        // failed to access file from file system

    }

    let rgb:[JPEG.RGB]      = image.unpack(as: JPEG.RGB.self), 

        size:(x:Int, y:Int) = image.size

    // ...

}

```

Encode an image: 

```swift 

import JPEG

func encode(jpeg path:String, size:(x:Int, y:Int), pixels:[JPEG.RGB], 

    compression:Double) // 0.0 = highest quality

    throws 

{

    let layout:JPEG.Layout = .init(

        format:     .ycc8,

        process:    .baseline, 

        components: 

        [

            1: (factor: (2, 2), qi: 0), // Y

            2: (factor: (1, 1), qi: 1), // Cb

            3: (factor: (1, 1), qi: 1), // Cr 

        ], 

        scans: 

        [

            .sequential((1, \.0, \.0), (2, \.1, \.1), (3, \.1, \.1)),

        ])

    let jfif:JPEG.JFIF = .init(version: .v1_2, density: (72, 72, .inches))

    let image:JPEG.Data.Rectangular = 

        .pack(size: size, layout: layout, metadata: [.jfif(jfif)], pixels: rgb)

    try image.compress(path: path, quanta: 

    [

        0: JPEG.CompressionLevel.luminance(  compression).quanta,

        1: JPEG.CompressionLevel.chrominance(compression).quanta

    ])

}

```