PeachImage

PeachImage is the pure .NET image codec library PeachPDF decodes every raster image with, and that PeachDrawing encodes the bitmaps it saves with. It reads and writes the formats the web uses (JPEG, PNG, GIF, WebP, AVIF, BMP, and TIFF for reading) as managed code only: no native library, no P/Invoke, no platform imaging API, so the same code runs on Windows, Linux, macOS, Android and in the browser. It targets .NET 8 and .NET 10.

PeachImage is a project of its own, released under the MIT license, and it is not versioned with PeachPDF. This page describes the version PeachPDF is built with (0.4.6), and the API reference for it is generated from that exact release, so what you read here and there is what you get by installing PeachPDF.

dotnet add package PeachImage

You do not need to add it to use PeachPDF: PeachPDF depends on it, so it arrives with the package. Reference it directly when your own code loads, converts or resizes images, as in the examples below.

Formats

The format is detected from the file’s contents, so nothing needs registering, and a file with the wrong extension still loads. A feature a codec does not implement throws a descriptive exception instead of producing a wrong image. Ask the library what it supports at run time with Image.SupportedFormats, which lists each format’s name, file extensions, MIME types, and whether it can decode and encode.

Loading, converting and saving

Image is a decoded raster: its Width, Height and PixelFormat, its pixels, and its metadata. Load from a path, a Stream, or bytes already in memory (no MemoryStream needed), and save in any format that can encode by naming it:

using PeachImage;
using PeachImage.Formats.Jpeg;

using var image = Image.Load("photo.webp");
Console.WriteLine($"{image.Width}x{image.Height} {image.PixelFormat}");

using var output = File.Create("resaved.jpg");
image.Save(output, "jpeg", new JpegEncoderOptions { Quality = 85 });

Each format has its own encoder options type under PeachImage.Formats.<Format>: JpegEncoderOptions (quality, chroma subsampling, progressive), PngEncoderOptions (compression level, color mode, palette size, dithering, interlacing), GifEncoderOptions, WebpEncoderOptions (lossless or lossy, quality), AvifEncoderOptions and BmpEncoderOptions. SaveAsync and LoadAsync exist for async I/O paths; the encode and decode themselves are CPU-bound, so only the stream read or write is awaited.

To learn what a file is without decoding it, use Image.Identify, which reads only the header:

using PeachImage;

using var stream = File.OpenRead("photo.avif");
ImageInfo info = Image.Identify(stream);
Console.WriteLine($"{info.Width}x{info.Height} {info.PixelFormat} ({info.FormatName})");

Image.TryLoad is the non-throwing form for untrusted input, returning false for a stream that is not an image it can read.

Pixels

The pixel buffer is exposed without copying:

using PeachImage;

using var image = Image.Load("photo.png");
Span<byte> pixels = image.GetPixelSpan();
Span<byte> firstRow = image.GetRowSpan(0);

PixelFormat says how to read it: Gray8, Rgb24, Rgba32, Cmyk32, and the 16-bit-per-channel Gray16, Rgb48 and Rgba64. A decoder keeps the source’s format by default (a CMYK JPEG stays CMYK, so its separations are not thrown away); pass decoder options to have the image converted to a format you ask for in the same pass.

Animated images

GIF and WebP with more than one frame load as an AnimatedImage with the same load and save shape:

using PeachImage;
using PeachImage.Formats.Gif;

var animation = AnimatedImage.Load("clip.gif");

foreach (AnimatedImageFrame frame in animation.Frames)
{
    Console.WriteLine($"{frame.Duration.TotalMilliseconds}ms, disposal={frame.Disposal}");
}

using var output = File.Create("resaved.gif");
animation.Save(output, "gif", new GifEncoderOptions { MaxColors = 128, Dither = true });

Frames come out fully composited, with their duration and disposal method. Image.IsAnimated and ImageInfo.IsAnimated tell you before you choose which loader to use.

Resizing

Resize offers fifteen resampling filters through ResamplingFilter, Bicubic by default, including Lanczos3, CatmullRom, MitchellNetravali, Box and NearestNeighbor. ResizeMode.Max treats the size as a bounding box: it scales down to fit, keeps the aspect ratio and never upscales.

using PeachImage;

using var image = Image.Load("photo.jpg");

using var thumbnail = image.Resize(200, 150);
using var sharper = image.Resize(200, 150, new ResizeOptions { Filter = ResamplingFilter.Lanczos3 });
using var fitted = image.Resize(200, 200, new ResizeOptions { Mode = ResizeMode.Max });

When the source already fits a ResizeMode.Max box, the same instance comes back rather than a copy, so do not keep using the original after disposing the result in that case. AnimatedImage.Resize resizes every frame as the frames are enumerated, keeping each one’s duration and disposal.

Color profiles and metadata

Image.Metadata carries what the file embedded: an ICC profile (GetIccColorProfile()), and the raw EXIF, XMP and other profile blocks as RawMetadataProfile entries. PeachPDF reads the ICC profile to embed an image with its color space intact, and ImageInfo.IsAdobeInvertedCmyk and IsYcck tell it when a JPEG’s CMYK samples are stored inverted. See Color and ICC profiles for what PeachPDF does with them.

Disposal

Image implements IDisposable, and most instances rent their pixel buffer from a shared pool that Dispose returns it to. Not disposing one is safe: it is collected like any other object, with no leak. Disposing matters for throughput under concurrent load, such as a service resizing many uploads at once, where reusing buffers cuts allocation and garbage collection. An AnimatedImage and the frames of its Frames need no disposal.

PeachImage in PeachPDF and PeachDrawing

• PeachPDF decodes the raster images a document references (<img>, CSS images, data: URIs) with PeachImage. A CMYK or ICC-profiled JPEG is embedded byte for byte rather than converted, and everything else is decoded to RGBA for the PDF writer. See Image loading and decoding.
• PeachDrawing draws into a RasterSurface and saves it through PeachImage’s encoders (RasterCanvas.Save takes a format name and an EncoderOptions), so any format above that can encode is a format a RasterCanvas can save.

API reference

The PeachImage API reference documents every public type and member. It sits beside the references for PeachPDF, PeachDrawing.Core, PeachDrawing and PeachDrawing.Text, and the pages of one link to the pages of another where they meet: a RasterCanvas.Save page links to the EncoderOptions it takes here.

License

PeachImage is MIT-licensed. Its license, and the notice for the one algorithm it references from libjpeg-turbo, are in its repository; see the license page for the components PeachPDF itself carries.