Watermark.Net

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Watermark.Net is an open-source .NET library for programmatically adding text and image watermarks to images. Built on SixLabors.ImageSharp, it provides a clean, extensible API for all your watermarking needs — from a single file to entire directory batches. Whether you need to protect copyrights, brand your media, or mark drafts, Watermark.Net makes image watermarking in C# simple and efficient.

Features

• 🖼️ Multi-format support — JPEG, PNG, BMP, GIF
• ✏️ Text watermarks — custom fonts, colors, sizes, rotation, and 9-zone positioning
• 🖌️ Image watermarks — PNG transparency, scaling, and opacity control (0.0–1.0)
• 🧱 Pave (tiling) mode — repeat the watermark across the entire image surface
• 🧩 9 preset positions — TopLeft, TopCenter, TopRight, CenterLeft, Center, CenterRight, BottomLeft, BottomCenter, BottomRight
• 🎨 Custom styling — background color, opacity, rotation angle, and padding
• 📁 Batch processing — watermark all images in a directory with a single method call
• 🔌 Dependency injection ready — IFileManager abstraction for testing and custom file I/O
• 🔄 Backward compatible — legacy Watermarker API still supported (marked as [Obsolete])

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Installation

Install the NuGet package:

dotnet add package Watermark.Net

Requires .NET 8 or later.

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Quick Start

Add a Text Watermark

using SixLabors.Fonts;
using SixLabors.ImageSharp;
using Watermark.Net.src.WatermarkNet.Core;
using Watermark.Net.src.WatermarkNet.Enums;
using Watermark.Net.src.WatermarkNet.Models.Definitions;

var pipeline = new WatermarkPipeline(new FileManager(), new ImageRenderer());

var watermark = new TextWatermark
{
    Text = "WATERMARK",
    Font = SystemFonts.CreateFont("Arial", 36),
    Layout = { Position = ImagePosition.BottomRight, Scale = 0.5f },
    Style = { Color = Color.White }
};

ResultImage result = pipeline.ProcessImage("input.jpg", "output", watermark);
Console.WriteLine($"Saved to: {result.Path}");

Add an Image Watermark

using SixLabors.ImageSharp;
using Watermark.Net.src.WatermarkNet.Core;
using Watermark.Net.src.WatermarkNet.Enums;
using Watermark.Net.src.WatermarkNet.Models.Definitions;

var pipeline = new WatermarkPipeline(new FileManager(), new ImageRenderer());

var watermark = new ImageWatermark
{
    ImagePath = "logo.png",
    Layout = { Scale = 0.3f, Position = ImagePosition.Center },
    Style = { Opacity = 0.7f, Pave = true }
};

List<ResultImage> results = pipeline.ProcessDirectory("images", "output", watermark);
Console.WriteLine($"Processed {results.Count} images");

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Architecture

Watermark.Net follows a clean pipeline architecture with clear separation of concerns:

┌──────────────────────────────────────┐
│           WatermarkPipeline          │  ← Orchestrator layer
│  (coordinates I/O and rendering)     │
├──────────────────────────────────────┤
│  IFileManager / FileManager          │  ← File I/O abstraction
│  (loading, saving, enumeration)      │
├──────────────────────────────────────┤
│           ImageRenderer              │  ← Pure rendering engine
│  (image processing, no I/O)          │
└──────────────────────────────────────┘

• WatermarkPipeline — the main entry point that orchestrates file operations and rendering.
• IFileManager / FileManager — abstracts all file system I/O. Swap this for custom storage or unit testing.
• ImageRenderer — a pure image processing engine. Accepts in-memory Image objects, returns processed Image instances. No file I/O dependency.

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Configuration Reference

WatermarkLayout

Controls where and how big the watermark appears.

Property	Type	Default	Description
Position	ImagePosition	TopLeft	One of 9 predefined positions
Scale	float	0	Scale factor relative to image size
RotateAngle	int	0	Rotation angle in degrees
Padding	float	0	Padding space around the watermark (px)

WatermarkStyle

Controls how the watermark looks.

Property	Type	Default	Description
Opacity	float	0	Transparency level — 0.0 (transparent) to 1.0 (opaque)
Pave	bool	false	When true, tiles the watermark across the image
Color	Color	default	Background or text color

ImagePosition

All 9 available positions:

Name	Description
TopLeft	Top-left corner
TopCenter	Top-center
TopRight	Top-right corner
CenterLeft	Middle-left
Center	Exact center
CenterRight	Middle-right
BottomLeft	Bottom-left corner
BottomCenter	Bottom-center
BottomRight	Bottom-right corner

Model types

Type	Description
TextWatermark	Text watermark configuration (Text, Font)
ImageWatermark	Image watermark configuration (ImagePath)
ResultImage	Output result (.Image + .Path)
IWatermarkDefinition	Base interface for custom watermark definitions

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Advanced Usage

Pave (Tiling) Mode

Tile the watermark across every position on the image:

var watermark = new TextWatermark
{
    Text = "DRAFT",
    Font = SystemFonts.CreateFont("Arial", 36),
    Style = { Color = Color.Red, Pave = true },
    Layout = { Scale = 0.3f }
};

Opacity Control

Create a subtle, semi-transparent watermark:

var watermark = new ImageWatermark
{
    ImagePath = "logo.png",
    Style = { Opacity = 0.3f },  // 30% opacity
    Layout = { Position = ImagePosition.Center, Scale = 0.5f }
};

Custom Positioning & Rotation

Place a rotated watermark with padding:

var watermark = new TextWatermark
{
    Text = "CONFIDENTIAL",
    Font = SystemFonts.CreateFont("Arial", 24),
    Layout =
    {
        Position = ImagePosition.TopLeft,
        RotateAngle = 45,
        Padding = 20
    }
};

Dependency Injection

Integrate with your DI container for better testability:

services.AddSingleton<IFileManager, FileManager>();
services.AddSingleton<ImageRenderer>();
services.AddTransient<WatermarkPipeline>();

Batch Directory Processing

Process all images in a directory with a single call:

var results = pipeline.ProcessDirectory("input_photos", "watermarked", textWatermark);

foreach (var result in results)
{
    Console.WriteLine($"✓ {result.Path}");
}

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Roadmap

• Improved pave mode - tiling isntead if 9 fixed positions
• AI remove protection - color noise, geometric distortion, DCT, texture blend etc.
• Common architecture imorovements

Contributing

Contributions are welcome! To ensure a smooth collaboration:

1. Fork the repository and create a feature branch.
2. Write tests for any new functionality (see the UnitTest project).
3. Run all tests before opening a pull request — make sure they pass.
4. Open a PR with a clear description of the changes.

All tests use sample images located in UnitTest/TestImages/.

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License

Watermark.Net is licensed under the MIT License.