stackotter/jpeg

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 s

[tutorials and example programs](examples/)

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

getting started

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

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

basic usage

Decode an image:

import JPEG
func decode(jpeg path:String) throws
{
    guard let image:JPEG.Data.Rectangular<JPEG.Common> = 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:

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<JPEG.Common> = .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<JPEG.Common> = 
        .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
    ])
}

Package Metadata

Repository: stackotter/jpeg

Default branch: master

README: README.md