Nextended.Imaging 10.1.32

Nextended.Imaging

Image processing — aspect-preserving resize, crop, colour replacement, brightness-based foreground picking, thumbnail generation, byte/data-URL conversion and MIME detection from magic bytes.

📖 Documentation: English · Deutsch

Installation

dotnet add package Nextended.Imaging

Warning This package builds on System.Drawing.Common, which Microsoft supports on Windows only from .NET 7 onwards. On Linux and macOS the System.Drawing types throw PlatformNotSupportedException. For cross-platform image work use ImageSharp or SkiaSharp instead — this package targets Windows services, desktop apps and Windows-hosted web apps.

Feature map

Quick start

Resize inside a bounding box, keeping the aspect ratio

using Nextended.Imaging;

using var image = ImageHelper.FromFile(@"C:\uploads\photo.jpg");

// CalculateResize works out the largest size that fits the box without distortion.
var target = ImageHelper.CalculateResize(image.Size, new Size(800, 600));
using var resized = image.ResizeImage(target);

resized.Save(@"C:\out\photo-800.jpg", ImageFormat.Jpeg);

Pass a ResizeMode when you want to control cropping versus letterboxing, or use the single-dimension overload:

// 400px wide, height follows the aspect ratio
using var thumb = ImageHelper.ResizeImage(image, 400);

// 400px tall instead
using var tall = ImageHelper.ResizeImage(image, 400, useSizeAsHeight: true);

Thumbnails as bytes

byte[] thumbnail = ImageHelper.GetImageThumbnailData(image, 200);

// Or: never go below a minimum in either dimension
byte[] minSized = ImageHelper.GetMinSizedImageThumbnailData(image, new Size(120, 120));

Detect the real type from the bytes, not the file extension

string mime = Miscellaneous.GetMimeFromBytes(uploadedBytes);   // reads the magic bytes
bool ok     = ImageHelper.IsValidImage(uploadedBytes);

A .png extension on a renamed executable does not fool GetMimeFromBytes — it inspects the header signature. Useful as an upload guard.

Readable text over an arbitrary image

var background = ImageHelper.FromFile(path).ReadImageColor();      // dominant colour
var foreground = Miscellaneous.GetOptimalForegroundColor(background);  // black or white, by brightness

int brightness = background.GetWeightedBrightness();  // perceptual, not a plain average

Colour replacement

using var recoloured = ImageHelper.ReplaceColor(bitmap, Color.Magenta, Color.Transparent);

The classic "magenta means transparent" sprite sheet, without a manual pixel loop.

Embedding in HTML

string tag = ImageHelper.ToHtmlImageString(image);   // <img src="data:image/png;base64,…">

FromHtmlImageString is the inverse, so a data-URL round trip needs no manual base64 handling.

Caching thumbnails

Nextended.Imaging depends on Nextended.Cache, so thumbnail generation composes with expression-based caching:

var bytes = _cache.ExecuteWithCache(this, self => self.BuildThumbnail(imageId, 200));

Supported frameworks

• net8.0
• net9.0
• net10.0

Dependencies

• Nextended.Core
• Nextended.Cache
• System.Drawing.Common

The Nextended family

The other 17 packages in the suite:

Core libraries

• Nextended.Core — Foundation library — extension methods, custom types (Money, Date, BaseId, SuperType), class mapping, deep clone, encryption, hashing and the code-generation attributes.
• Nextended.Cache — Expression-based caching — automatic cache keys from method expressions, CacheProvider with condition-based invalidation, thread-safe AddOrGetExisting.

Data access

• Nextended.EF — Entity Framework Core extensions — graph loading (LoadGraphAsync, IncludeAll, MultiInclude), declarative include definitions, paging, dynamic sorting and bulk operations.

ASP.NET Core & web

• Nextended.Web — ASP.NET Core utilities — zero-config OData (AddODataAuto), composable IQueryable OData appliers, strongly typed controller URLs, streaming download helpers and a background executor that can replay a captured request.
• Nextended.ResponseFilters — Fluent, provider-agnostic pipeline that redacts, masks, rounds, truncates, hashes, prunes and restructures response DTOs before serialization — per request, per user, per permission.
• Nextended.ResponseFilters.AspNetCore — ASP.NET Core adapter for Nextended.ResponseFilters — registers the pipeline as a global IAsyncResultFilter and replays structural edits against the serialized JSON tree.

UI libraries

• Nextended.Blazor — Blazor helpers — IBrowserFile extensions (bytes, data URLs, downloads), a hierarchical model for browsing inside uploaded zip/tar/rar archives, MIME-type detection and component-parameter reflection.
• Nextended.UI — WPF and Windows desktop helpers — a global input-binding manager with hold/sequence matching, DirectInput and XInput gamepad readers, key-bind capture controls, converters, behaviours, markup extensions and runtime-defined PropertyGrid types.

Code generation & tooling

• Nextended.Imaging — Image processing — aspect-preserving resize, crop, colour replacement, brightness-based foreground picking, thumbnail generation, byte/data-URL conversion and MIME detection from magic bytes. (this package)
• Nextended.CodeGen — Roslyn source generator — DTOs and interfaces from your entities, strongly typed classes from JSON/XML, lookup tables from Excel, and documentation from source files.

.NET Aspire hosting

• Nextended.Aspire — Conditional AppHost builder extensions — WithReferenceIf / WaitForIf / WithExplicitStartIf, strongly typed environment variables from config objects, HTTPS dev-cert wiring, Docker guards, GitHub-source resources and npm app discovery.
• Nextended.Aspire.Hosting.Supabase — The complete Supabase stack — Postgres, Auth (GoTrue), REST, Realtime, Storage, Studio, Kong and Edge Functions — as one composable Aspire resource.
• Nextended.Aspire.Hosting.N8n — The n8n workflow-automation platform as an Aspire resource, with Postgres persistence, workflow import and a typed client for triggering workflows from .NET.
• Nextended.Aspire.Hosting.Grafana — Grafana, Prometheus, Loki, Tempo, Promtail, cAdvisor, postgres_exporter and the OpenTelemetry Collector as composable resources with auto-provisioned datasources.
• Nextended.Aspire.Hosting.WebDataStudio — WebDataStudio — a browser database studio for PostgreSQL, MySQL, SQL Server, SQLite, Oracle, DuckDB, ClickHouse, MongoDB and Redis — wired to the databases of your stack.
• Nextended.Aspire.Hosting.AspireUI — AspireUI — the visual AppHost builder — as a resource inside your own Aspire stack, with an optional pre-seeded admin user and a starter stack built from your project paths.
• Nextended.Aspire.Hosting.LocalAI — Self-hosted, OpenAI-compatible multimodal AI — image generation, text-to-speech, speech-to-text and video — with gallery model management, GPU support and Open WebUI.
• Nextended.Aspire.Hosting.Php — Run PHP endpoints inside your Aspire stack — a docroot folder or a single router script served by PHP's built-in web server, with php.ini settings as fluent options.

Links

• 📦 NuGet package
• 📖 Documentation — English
• 📖 Dokumentation — Deutsch
• 🏠 Documentation portal
• 🧑‍💻 Source code
• 🐛 Report an issue

License

GPL-3.0-or-later — see LICENSE.