Watermark.Net

Watermark.Net is a modern, cross-platform .NET image watermarking library for adding text and image watermarks to photos and graphics using C#.

Built on top of SixLabors.ImageSharp, Watermark.Net provides a clean and extensible API for:

• image watermarking in .NET
• batch image processing
• copyright protection
• logo overlays
• branding automation
• draft/staging image generation

Perfect for ASP.NET applications, media pipelines, SaaS platforms, desktop tools, automation scripts, and backend image processing services.

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Why Watermark.Net?

• ✅ Modern .NET 8+ architecture
• ✅ Fully cross-platform (Windows, Linux, macOS)
• ✅ Powered by ImageSharp
• ✅ Simple and clean API
• ✅ Batch directory watermarking
• ✅ Text and image watermark support
• ✅ Tiling / repeated watermark mode
• ✅ Dependency Injection friendly
• ✅ Open-source and MIT licensed

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Features

Text Watermarks

Add fully customizable text overlays:

• Custom fonts
• Font sizing
• Rotation
• Opacity
• Padding
• 9-position alignment system
• Tiled/pattern mode

Image Watermarks

Overlay logos or transparent PNG files:

• PNG transparency support
• Opacity control
• Scaling
• Positioning
• Repeated/tiled mode

Batch Processing

Process entire folders of images with a single method call.

Supports:

• JPEG
• PNG
• BMP
• GIF

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Installation

Install from NuGet:

dotnet add package Watermark.Net

Or via Package Manager:

Install-Package Watermark.Net

NuGet package:

https://www.nuget.org/packages/Watermark.Net/

Requirements:

• .NET 8 or later

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Quick Start

Add a Text Watermark

using SixLabors.Fonts;
using SixLabors.ImageSharp;
using WatermarkNet.Core;
using WatermarkNet.Enums;
using WatermarkNet.Models.Definitions;

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

var watermark = new TextWatermark
{
    Text = "CONFIDENTIAL",
    Font = SystemFonts.CreateFont("Arial", 36),

    Layout =
    {
        Position = ImagePosition.BottomRight,
        Scale = 0.5f
    },

    Style =
    {
        Color = Color.White,
        Opacity = 0.8f
    }
};

ResultImage result = pipeline.ProcessImage(
    "input.jpg",
    "output",
    watermark
);

Console.WriteLine($"Saved to: {result.Path}");

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Add an Image Watermark

using SixLabors.ImageSharp;
using WatermarkNet.Core;
using WatermarkNet.Enums;
using WatermarkNet.Models.Definitions;

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

var watermark = new ImageWatermark
{
    ImagePath = "logo.png",

    Layout =
    {
        Position = ImagePosition.Center,
        Scale = 0.3f
    },

    Style =
    {
        Opacity = 0.7f,
        Pave = true
    }
};

List<ResultImage> results = pipeline.ProcessDirectory(
    "images",
    "output",
    watermark
);

Console.WriteLine($"Processed {results.Count} images");

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Common Use Cases

Watermark.Net is commonly used for:

• Photo copyright protection
• E-commerce product branding
• SaaS image pipelines
• AI-generated image labeling
• CMS systems
• Social media automation
• Media processing backends
• ASP.NET image services
• Bulk image processing
• Internal document marking

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Architecture

Watermark.Net follows a lightweight pipeline architecture with clear separation of responsibilities.

┌──────────────────────────────────────┐
│          WatermarkPipeline           │
│      Main orchestration layer        │
├──────────────────────────────────────┤
│       IFileManager / FileManager     │
│         File system abstraction      │
├──────────────────────────────────────┤
│            ImageRenderer             │
│      Pure image rendering engine     │
└──────────────────────────────────────┘

Components

WatermarkPipeline

Main entry point responsible for:

• file handling
• pipeline orchestration
• watermark processing

ImageRenderer

Pure rendering engine:

• no filesystem dependency
• in-memory image processing
• reusable rendering logic

IFileManager

Abstraction layer for:

• local files
• cloud storage integration
• testing/mocking

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Watermark Types

Type	Description
TextWatermark	Text-based watermark configuration
ImageWatermark	Image/logo watermark configuration
ResultImage	Processing result model
IWatermarkDefinition	Base watermark abstraction

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Positioning System

Supports 9 built-in alignment positions:

Position
TopLeft
TopCenter
TopRight
CenterLeft
Center
CenterRight
BottomLeft
BottomCenter
BottomRight

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Advanced Usage

Tiled / Pave Mode

Repeat watermark across the entire image:

var watermark = new TextWatermark
{
    Text = "DRAFT",
    Font = SystemFonts.CreateFont("Arial", 36),

    Style =
    {
        Color = Color.Red,
        Pave = true
    },

    Layout =
    {
        Scale = 0.3f
    }
};

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Rotation & Padding

var watermark = new TextWatermark
{
    Text = "CONFIDENTIAL",
    Font = SystemFonts.CreateFont("Arial", 24),

    Layout =
    {
        Position = ImagePosition.TopLeft,
        RotateAngle = 45,
        Padding = 20
    }
};

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Dependency Injection

services.AddSingleton<IFileManager, FileManager>();

services.AddSingleton<ImageRenderer>();

services.AddTransient<WatermarkPipeline>();

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Batch Directory Processing

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

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

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Roadmap

Planned improvements:

• Async API support
• Stream-based processing
• SVG watermark support
• Better tiling engine
• Additional blend modes
• Performance optimizations

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Contributing

Contributions are welcome.

To contribute:

1. Fork the repository
2. Create a feature branch
3. Add or update tests
4. Run the test suite
5. Open a Pull Request

Test assets are located in:

UnitTest/TestImages/

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License

Watermark.Net is licensed under the MIT License.

See the LICENSE file for details.

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Keywords

.NET watermark library, C# watermark library, ImageSharp watermarking, image watermarking .NET, text watermark C#, image overlay library, batch image processing, ASP.NET image watermarking, cross-platform image processing, watermark NuGet package