2D Image Filter

A comprehensive collection of pixel art scaling algorithms for upscaling low-resolution computer and console graphics.

📖 Overview

2D Image Filter is a powerful library that brings together the most popular image scaling algorithms specifically designed for pixel art and low-resolution graphics. Unlike traditional image scaling methods that often blur or distort pixel art, these algorithms preserve the crisp, clean aesthetic while intelligently enlarging images.

🎯 Project Goals

• Algorithm Collection: Gather all available pixel art scaling filters in one comprehensive library
• Enhanced Flexibility: Convert rigid color comparisons into parameterized "IsLike" functions
• Wide Compatibility: Support various graphics types with configurable similarity thresholds
• Performance: Optimized implementations using unsafe code for maximum speed

🔧 Key Innovation

Traditional scaling algorithms use hard-coded comparisons:

(color1 == color2) ? color1 : color3

Our enhanced approach uses flexible similarity functions:

(color1.IsLike(color2)) ? Interpolate(color1, color2) : color3

🚀 Features

📦 Multiple Distribution Formats

• Standalone Application: GUI application for interactive image processing
• Paint.NET Plugin: Seamless integration with Paint.NET editor
• Library: .NET library for programmatic use in your applications

🎨 Supported Scaling Algorithms

Classic Pixel Art Scalers

• Eagle Family: Eagle 2x/3x, Super Eagle
• SaI Family: 2xSaI, Super2xSaI (Kreed/DOSBox)
• Scale Family: Scale2x/3x (MAME - Andrea Mazzoleni)
• AdvInterp: AdvInterp2x/3x (MAME)

High Quality Scalers

• HQ Family: HQ2x/3x/4x (Maxim Stepin)
• LQ Family: LQ2x/3x/4x (SNES9x/AdvMAME)
• nQ Family: nQx Bold and Smart versions

Modern Advanced Scalers

• XBR Family: XBR2x/3x/4x Normal and NonBlend (Hyllian)
• XBRz: High quality scaling (Zenju)
• Reverse AA: Anti-aliasing filter (Hyllian)

Specialized Effects

• CRT Effects: MAME TV/RGB, Hawkynt TV effects
• Scanlines: Horizontal/vertical scanline effects
• Bilinear Plus: VBA enhanced bilinear filtering
• FNES Filters: DES, 2xSCL variants

Resampling Kernels

• Comprehensive collection of windowing functions
• Bicubic, Lanczos, and exotic mathematical kernels
• Support for custom radius and parameters

💻 Installation & Usage

Prerequisites

• .NET Framework 4.5 or higher
• Windows Vista/7/8/10/11

Quick Start

Option 1: Standalone Application

1. Download from Releases
2. Extract and run ImageResizer.exe
3. Load your image and select a scaling algorithm
4. Configure parameters and export the result

Option 2: Paint.NET Plugin

1. Download the Paint.NET plugin
2. Extract to your Paint.NET Effects folder
3. Restart Paint.NET
4. Find "Pixel Art Scaling" in the Effects menu

Option 3: Command Line Interface

ImageResizer.exe load input.png resize auto "HQ 2x" save output.png
ImageResizer.exe load sprite.bmp resize 400% "XBR 3x" save scaled_sprite.png

Building from Source

# Clone the repository
git clone https://github.com/Hawkynt/2dimagefilter.git
cd 2dimagefilter

# Build the solution
dotnet build ImageResizer.sln -c Release

# Or build individual projects
dotnet build ImageResizerLibrary/ImageResizerLibrary.csproj
dotnet build ImageResizer/ImageResizer.csproj

📚 Documentation

Command Line Usage

The application supports powerful command-line scripting:

# Basic usage
ImageResizer.exe load <input> resize <dimensions> <method> save <output>

# Dimension formats
resize auto "Scale2x"          # Auto-detect from algorithm
resize 320x240 "Bicubic"       # Specific dimensions  
resize w128 "HQ 2x"            # Width only (height auto)
resize h96 "Eagle"             # Height only (width auto)
resize 200% "XBR 3x"           # Percentage scaling

# Parameter examples
resize auto "Bicubic(radius=1.5,vbounds=wrap)"
resize 2x2 "HQ 2x(thresholds=1,repeat=2)"

Supported Parameters

• radius: Filter radius for resampling kernels
• thresholds: Enable/disable similarity thresholds
• repeat: Number of filter repetitions
• vbounds/hbounds: Out-of-bounds handling (const, half, whole, wrap, transparent)
• centered: Use centered grid for filtering

🎮 Perfect For

• Pixel Art: Classic video game sprites and artwork
• Retro Gaming: Emulator enhancement and ROM hacking
• Digital Art: Low-resolution artwork enlargement
• Game Development: Asset upscaling for modern displays
• Academic Research: Comparative analysis of scaling algorithms

🏆 Algorithm Credits

This project implements algorithms from numerous sources:

• Eagle/Super Eagle: Derek Liauw Kie Fa (Kreed), ZSNES team
• Scale2x/3x: Andrea Mazzoleni (MAME)
• HQ2x/3x/4x: Maxim Stepin
• XBR: Hyllian
• XBRz: Zenju
• Resampling Kernels: Pascal Getreuer
• FNES Filters: FNES emulator team
• VBA Enhancements: VBA-rr team

📄 License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.

🤝 Contributing

Contributions are welcome! Whether you want to:

• Add new scaling algorithms
• Improve existing implementations
• Fix bugs or enhance performance
• Improve documentation

Please feel free to open an issue or submit a pull request.

📊 Downloads

• Standalone Application: Download v2.0.0
• Paint.NET Plugin: Download v2.0.0