BRISQUE Refactoring Journal: C++ to C#

Document Information

Field

Value

Project

Luxoria BRISQUE Implementation

Original Language

C++ (OpenCV 4.10.0)

Target Language

C# (.NET 8.0)

Architecture

Native Interop via P/Invoke

License

Apache 2.0

1. Executive Summary

This document records the technical decisions and architectural choices made during the port of the BRISQUE (Blind/Referenceless Image Spatial Quality Evaluator) algorithm from a native C++ implementation to a .NET C# library.

Project Goal

Create a NuGet package for seamless integration into Luxoria, our C# WinUI desktop application, while preserving the performance characteristics of the native OpenCV implementation.

Key Achievements

Zero-configuration deployment: Single dotnet add package command
Native performance preserved: P/Invoke wrapper around optimized C++ code
Multi-architecture support: x86, x64, and ARM64 Windows
Minimal footprint: Strict as possible, one goal, one task to perform

Trade-off Summary

Aspect

Decision

Outcome

Performance

Native code via P/Invoke

CPU-intensive operations remain optimized

Distribution

Embedded native libraries

Zero external dependencies

API Surface

Simplified wrapper

Easy adoption for .NET developers

Platform

Windows-focused

Optimal Visual Studio/NuGet integration

2. Project Context

2.1 What is BRISQUE?

BRISQUE (Blind/Referenceless Image Spatial Quality Evaluator) is a no-reference image quality assessment algorithm that:

Requires no reference image for comparison
Uses natural scene statistics (NSS) in the spatial domain
Extracts 36 features from locally normalized luminance coefficients
Employs SVM regression to predict perceptual quality scores (0-100, lower is better)

2.2 Why This Refactoring?

The Luxoria application needed a reliable image quality assessment solution. Rather than reimplementing a complex algorithm from scratch, we chose to wrap the battle-tested OpenCV implementation, gaining:

Proven accuracy: OpenCV's BRISQUE is validated against academic benchmarks
Optimized performance: Years of C++ optimization work
Reduced risk: No algorithmic implementation bugs
Faster delivery: Wrapper approach vs full reimplementation

2.3 Original Implementation (C++)

brisquecpp/
├── includes/
│   └── BrisqueAlgorithm.hpp    # 41 lines - Wrapper class
├── main.cpp                     # 60 lines - CLI entry point
├── CMakeLists.txt              # Build configuration
└── models/
    ├── brisque_model_live.yml  # Pre-trained SVM model (555 KB)
    └── brisque_range_live.yml  # Feature normalization (1.3 KB)

2.4 Target Implementation (C#)

brisquecsharp/
├── Luxoria.Algorithm.BrisqueScore/
│   ├── BrisqueScore.cs                    # 113 lines - P/Invoke wrapper
│   ├── NativeLibraries/
│   │   ├── x86/brisque_quality.dll       # 4.2 MB
│   │   ├── x64/brisque_quality.dll       # 5.6 MB
│   │   └── arm64/brisque_quality.dll     # 3.9 MB
│   └── Luxoria.Algorithm.BrisqueScore.csproj
└── BrisqueScore.TestMain/                 # Reference application
└── BrisqueScore.Tests/                    # Testing enforcement policy (testing codebase)

3. Architecture Comparison

3.1 C++ Architecture

┌─────────────────────────────────────────────────────────────┐
│                      main.cpp (CLI)                         │
│  - Argument parsing                                         │
│  - Image loading (cv::imread)                               │
│  - Grayscale conversion (cv::cvtColor)                      │
└─────────────────────────┬───────────────────────────────────┘
                          │
                          ▼
┌─────────────────────────────────────────────────────────────┐
│              BrisqueAlgorithm (Facade)                      │
│  namespace: luxoria::filter::algorithms                     │
│  - cv::Ptr<cv::quality::QualityBRISQUE> _model              │
│  - compute(cv::Mat) -> double                               │
└─────────────────────────┬───────────────────────────────────┘
                          │
                          ▼
┌─────────────────────────────────────────────────────────────┐
│              OpenCV Quality Module                          │
│  - Feature extraction (36 NSS features)                     │
│  - SVM prediction                                           │
└─────────────────────────────────────────────────────────────┘

3.2 C# Architecture

┌─────────────────────────────────────────────────────────────┐
│                Luxoria WinUI Application                    │
│  using Luxoria.Algorithm.BrisqueScore;                      │
└─────────────────────────┬───────────────────────────────────┘
                          │
                          ▼
┌─────────────────────────────────────────────────────────────┐
│              BrisqueInterop : IDisposable                   │
│  - Static constructor: ExtractAndLoadNativeLibrary()        │
│  - Architecture detection (x86/x64/arm64)                   │
│  - Resource extraction to temp directory                    │
│  - Validation layer (file existence checks)                 │
│  - P/Invoke declarations                                    │
└─────────────────────────┬───────────────────────────────────┘
                          │ P/Invoke (Cdecl)
                          ▼
┌─────────────────────────────────────────────────────────────┐
│              brisque_quality.dll (Native)                   │
│  - CreateBrisqueAlgorithm()                                 │
│  - ComputeBrisqueScore()                                    │
│  - ReleaseBrisqueAlgorithm()                                │
│  + OpenCV (statically linked)                               │
└─────────────────────────────────────────────────────────────┘

3.3 Key Architectural Differences

Aspect

C++

Purpose

CLI tool

Library for Luxoria

OpenCV Access

Direct linking

Indirect via native DLL

Image Input

cv::Mat objects

File path strings

Memory Model

RAII with smart pointers

Managed + IDisposable

Distribution

Executable

NuGet package

4. Technical Trade-offs Analysis

4.1 Interop Strategy: P/Invoke vs Pure Managed

We evaluated two approaches for bringing BRISQUE to .NET:

Option A: Pure C# Reimplementation

Pros

Cons

No native dependencies

Requires reimplementing complex algorithms

True cross-platform

Performance penalty on CPU math

Simpler deployment

~2000+ lines of code to maintain

Risk of algorithmic discrepancies

Option B: P/Invoke Wrapper (Selected)

Pros

Cons

Leverages optimized OpenCV code

Platform-specific binaries

Only ~113 lines to maintain

Larger package size

Guaranteed algorithmic consistency

Native memory management

Proven implementation

Decision: P/Invoke was the clear winner. BRISQUE involves complex mathematical operations (DCT, SVD, SVM) that OpenCV has spent years optimizing. The wrapper approach reduced development effort by approximately 90% while preserving performance.

4.2 Library Embedding vs External Dependencies

Option A: External DLL Reference

// Would require users to install OpenCV separately
[DllImport("opencv_quality4100.dll")]

Pros

Cons

Smaller package

Complex installation

Shared across apps

Version compatibility issues

PATH configuration required

Support burden

Option B: Embedded Resources (Selected)

<EmbeddedResource Include="NativeLibraries\x64\brisque_quality.dll" />

Pros

Cons

Zero-config deployment

~14MB total package size

Version-locked

Cannot share OpenCV

Works everywhere

Temp directory usage

NuGet "just works"

Decision: Developer experience trumps package size. When someone adds our package, it should work immediately without additional setup steps.

4.3 Static vs Dynamic Linking (Native Side)

The native DLLs statically link OpenCV:

set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")

Architecture

DLL Size

Contents

x86

4.2 MB

OpenCV core + quality (static)

x64

5.6 MB

OpenCV core + quality (static)

arm64

3.9 MB

OpenCV core + quality (static)

Trade-off: Larger binaries but guaranteed compatibility. No DLL hell.

5. Design Decisions

5.1 API Surface Design

C++ Original API

class BrisqueAlgorithm {
public:
    BrisqueAlgorithm(std::string modelPath, std::string rangePath);
    double compute(cv::Mat img);
    ~BrisqueAlgorithm();
};

C# Wrapper API

public class BrisqueInterop : IDisposable {
    public BrisqueInterop(string modelPath, string rangePath);
    public double ComputeScore(string imagePath);
    public void Dispose();
}

Design Changes Explained

Change

Rationale

cv::Mat → string imagePath

Avoids exposing OpenCV types to managed code

compute() → ComputeScore()

.NET naming conventions (PascalCase, descriptive)

Destructor → IDisposable

Standard .NET pattern for unmanaged resources

5.2 Native Function Signatures

Three clean P/Invoke entry points:

[DllImport("brisque_quality", CallingConvention = CallingConvention.Cdecl)]
private static extern IntPtr CreateBrisqueAlgorithm(string modelPath, string rangePath);

[DllImport("brisque_quality", CallingConvention = CallingConvention.Cdecl)]
private static extern double ComputeBrisqueScore(IntPtr brisqueInstance, string imagePath);

[DllImport("brisque_quality", CallingConvention = CallingConvention.Cdecl)]
private static extern void ReleaseBrisqueAlgorithm(IntPtr instance);

Design Rationale:

Cdecl convention: Standard for C++ exports
IntPtr for instances: Opaque handle hides implementation details
Explicit release: Required because GC doesn't manage native memory

5.3 Namespace Design

Language

Namespace

C++

luxoria::filter::algorithms

Luxoria.Algorithm.BrisqueScore

The C# namespace was simplified while maintaining consistency with Luxoria's naming conventions.

6. Memory Management

6.1 C++ Memory Model

class BrisqueAlgorithm {
private:
    cv::Ptr<cv::quality::QualityBRISQUE> _model;  // Reference-counted smart pointer

public:
    ~BrisqueAlgorithm() {
        _model.release();  // Explicit release (optional due to smart pointer)
    }
};

6.2 C# Memory Model

public class BrisqueInterop : IDisposable {
    private IntPtr _brisqueInstance;  // Opaque handle to native object

    public void Dispose() {
        if (_brisqueInstance != IntPtr.Zero) {
            ReleaseBrisqueAlgorithm(_brisqueInstance);
            _brisqueInstance = IntPtr.Zero;  // Prevent double-free
        }
    }
}

6.3 Memory Ownership

┌───────────────────────────────────────────────────┐
│              Managed Heap (.NET)                  │
│  ┌───────────────────────────────────────────┐    │
│  │  BrisqueInterop instance                  │    │
│  │  - _brisqueInstance: IntPtr (8 bytes)     │    │
│  └──────────────────┬────────────────────────┘    │
└─────────────────────┼─────────────────────────────┘
                      │ Points to
                      ▼
┌───────────────────────────────────────────────────┐
│              Native Heap (C++)                    │
│  ┌───────────────────────────────────────────┐    │
│  │  BrisqueAlgorithm instance                │    │
│  │  └─> QualityBRISQUE (SVM model ~555KB)    │    │
│  └───────────────────────────────────────────┘    │
└───────────────────────────────────────────────────┘

6.4 Safety Measures

Issue

Mitigation

Forgetting Dispose()

Recommend using statement

Double disposal

IntPtr.Zero check prevents double-free

Invalid instance

Constructor throws if creation fails

7. Platform Strategy

7.1 Windows-Focused Design

The library targets Windows exclusively because:

Luxoria Integration: Our main application (Luxoria) is a C# WinUI desktop app targeting Windows
Visual Studio Ecosystem: Primary development environment for the team
NuGet Distribution: Seamless package management in Visual Studio
Enterprise Target: Most enterprise deployments are Windows-based

7.2 Architecture Detection

string architecture = RuntimeInformation.ProcessArchitecture switch {
    Architecture.X86 => "x86",
    Architecture.X64 => "x64",
    Architecture.Arm64 => "arm64",
    _ => throw new NotSupportedException("Unsupported architecture")
};

7.3 Supported Configurations

Architecture

Platform

Status

x86

Windows 32-bit

Supported

x64

Windows 64-bit

Supported

ARM64

Windows on ARM

Supported

7.4 Native Library Loading

private static void ExtractAndLoadNativeLibrary() {
    // 1. Detect architecture
    string architecture = RuntimeInformation.ProcessArchitecture switch { ... };

    // 2. Build resource name
    string resourceName = $"Luxoria.Algorithm.BrisqueScore.NativeLibraries.{architecture}.brisque_quality.dll";

    // 3. Extract to temp directory
    string tempPath = Path.Combine(Path.GetTempPath(), "LuxoriaNative");
    Directory.CreateDirectory(tempPath);

    // 4. Write resource to disk and load
    NativeLibrary.Load(dllPath);
}

8. Distribution Strategy

8.1 NuGet Package Structure

Luxoria.Algorithm.BrisqueScore.3.0.3.4100.nupkg
├── lib/net8.0/
│   └── Luxoria.Algorithm.BrisqueScore.dll
├── logo128x128.png
├── README.md
└── [embedded in assembly]
    ├── NativeLibraries.x86.brisque_quality.dll
    ├── NativeLibraries.x64.brisque_quality.dll
    └── NativeLibraries.arm64.brisque_quality.dll

8.2 Installation

# Via dotnet CLI
dotnet add package Luxoria.Algorithm.BrisqueScore

# Via Package Manager Console
Install-Package Luxoria.Algorithm.BrisqueScore

8.3 Usage in Luxoria

using Luxoria.Algorithm.BrisqueScore;

// In your image processing service
public class ImageQualityService {
    public double AssessQuality(string imagePath) {
        using var brisque = new BrisqueInterop(
            "models/brisque_model_live.yml",
            "models/brisque_range_live.yml"
        );
        return brisque.ComputeScore(imagePath);
    }
}

8.4 Model Files

Model files are distributed separately (not in the NuGet package):

File

Size

Purpose

brisque_model_live.yml

555 KB

Pre-trained SVM model

brisque_range_live.yml

1.3 KB

Feature normalization ranges

Rationale: Users may want custom-trained models. Keeping models separate follows separation of concerns.

9. Error Handling

9.1 Validation Layer

The C# wrapper provides comprehensive input validation before calling native code:

public BrisqueInterop(string modelPath, string rangePath) {
    if (string.IsNullOrWhiteSpace(modelPath) || !File.Exists(modelPath))
        throw new FileNotFoundException($"Model file not found: {modelPath}");

    if (string.IsNullOrWhiteSpace(rangePath) || !File.Exists(rangePath))
        throw new FileNotFoundException($"Range file not found: {rangePath}");

    _brisqueInstance = CreateBrisqueAlgorithm(modelPath, rangePath);
    if (_brisqueInstance == IntPtr.Zero)
        throw new InvalidOperationException("Failed to create BRISQUE algorithm instance.");
}

public double ComputeScore(string imagePath) {
    if (string.IsNullOrWhiteSpace(imagePath) || !File.Exists(imagePath))
        throw new FileNotFoundException($"Image file not found: {imagePath}");

    return ComputeBrisqueScore(_brisqueInstance, imagePath);
}

9.2 Exception Types

Scenario

Exception

Message Pattern

Model not found

FileNotFoundException

"Model file not found: {path}"

Range not found

FileNotFoundException

"Range file not found: {path}"

Image not found

FileNotFoundException

"Image file not found: {path}"

Native creation failure

InvalidOperationException

"Failed to create BRISQUE algorithm instance."

Unsupported architecture

NotSupportedException

"Unsupported architecture"

9.3 Comparison with C++

Error Type

C++ Behavior

C# Behavior

Missing file

stderr + exit code

Structured exception

Invalid image

OpenCV exception

Pre-validated in managed code

Out of memory

std::bad_alloc

OutOfMemoryException

10. API Design

10.1 Side-by-Side Comparison

C++ Usage:

#include "BrisqueAlgorithm.hpp"

cv::Mat img = cv::imread("image.jpg", cv::IMREAD_COLOR);
cv::Mat gray;
cv::cvtColor(img, gray, cv::COLOR_BGR2GRAY);

luxoria::filter::algorithms::BrisqueAlgorithm brisque(
    "models/brisque_model_live.yml",
    "models/brisque_range_live.yml"
);

double score = brisque.compute(gray);
std::cout << "BRISQUE Score: " << score << std::endl;

C# Usage:

using Luxoria.Algorithm.BrisqueScore;

using var brisque = new BrisqueInterop(
    "models/brisque_model_live.yml",
    "models/brisque_range_live.yml"
);

double score = brisque.ComputeScore("image.jpg");
Console.WriteLine($"BRISQUE Score: {score}");

10.2 API Improvements in C#

Improvement

Description

Simpler input

File path instead of cv::Mat handling

Automatic grayscale

Conversion happens in native layer

Using statement

Resource cleanup via IDisposable

Strong typing

No need to handle OpenCV types

11. Build System

11.1 C++ Build (CMake + vcpkg)

cmake_minimum_required(VERSION 3.23)
project(BRISQUEQuality)

set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# Static runtime linking
set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")

find_package(OpenCV REQUIRED)

add_executable(brisque_quality main.cpp)
target_include_directories(brisque_quality PUBLIC ${CMAKE_SOURCE_DIR}/includes)
target_link_libraries(brisque_quality ${OpenCV_LIBS})

11.2 C# Build (MSBuild)

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
    <PackageId>Luxoria.Algorithm.BrisqueScore</PackageId>
    <Version>3.0.3.4100</Version>
  </PropertyGroup>

  <ItemGroup>
    <EmbeddedResource Include="NativeLibraries\arm64\brisque_quality.dll" />
    <EmbeddedResource Include="NativeLibraries\x64\brisque_quality.dll" />
    <EmbeddedResource Include="NativeLibraries\x86\brisque_quality.dll" />
  </ItemGroup>
</Project>

11.3 CI/CD Pipeline

C++ Build Matrix (GitHub Actions):

Builds for x86, x64, arm64 on Windows
Uses vcpkg for OpenCV dependency
Outputs architecture-specific DLLs

C# Build:

.NET 8.0 SDK
Packages native DLLs as embedded resources
Produces NuGet package

12. Lessons Learned

12.1 What Worked Well

P/Invoke Approach
- Minimal code to maintain (~113 lines)
- Leveraged battle-tested OpenCV implementation
- Fast time to production
Embedded Resources
- Seamless NuGet installation experience
- No external dependency issues
- Version consistency guaranteed
Static Linking
- Single DLL per architecture
- No dependency conflicts
- Predictable deployment
Comprehensive Validation
- Pre-flight checks catch errors early
- Clear, actionable error messages
- Prevents crashes in native code

12.2 Challenges Overcome

vcpkg Integration
- Initial path configuration required iteration
- Cross-architecture builds needed separate CI jobs
- Solution: Documented workflow in CI/CD
Resource Naming
- Assembly resource names must match exactly
- Solution: Explicit LogicalName in .csproj
Model File Distribution
- Initially confusing for users
- Solution: Clear documentation and examples

12.3 TODO / Technical Debt

Item

Priority

Description

Async API

Low

Add ComputeScoreAsync for UI responsiveness

Batch processing

Low

Process multiple images efficiently

13. Conclusion

13.1 Project Success Metrics

Goal

Status

NuGet package for Visual Studio

Achieved

Zero-configuration deployment

Achieved

Integration with Luxoria

Achieved

Native performance preserved

Achieved

13.2 Final Architecture

The refactoring successfully transformed a C++ CLI tool into a polished .NET library:

┌────────────────────────────────────────────────────────────────┐
│                    Luxoria Application                         │
│                    (C# WinUI Desktop)                          │
└────────────────────────────┬───────────────────────────────────┘
                             │ NuGet Reference
                             ▼
┌────────────────────────────────────────────────────────────────┐
│           Luxoria.Algorithm.BrisqueScore (NuGet)               │
│  ┌──────────────────────────────────────────────────────────┐  │
│  │  BrisqueInterop.cs                                       │  │
│  │  - Input validation                                      │  │
│  │  - Architecture detection                                │  │
│  │  - Resource extraction                                   │  │
│  │  - P/Invoke wrapper                                      │  │
│  │  - IDisposable pattern                                   │  │
│  └──────────────────────────────────────────────────────────┘  │
│  ┌──────────────────────────────────────────────────────────┐  │
│  │  Embedded Native Libraries                               │  │
│  │  - x86/brisque_quality.dll (4.2 MB)                      │  │
│  │  - x64/brisque_quality.dll (5.6 MB)                      │  │
│  │  - arm64/brisque_quality.dll (3.9 MB)                    │  │
│  └──────────────────────────────────────────────────────────┘  │
└────────────────────────────────────────────────────────────────┘

13.3 Key Takeaways

Wrap, don't rewrite: When mature native libraries exist, wrapping is often the better choice
Prioritize developer experience: Zero-config installation pays dividends
Validate early: Catch errors in managed code before they reach native code
Document decisions: This journal captures the "why" for future maintainers

Appendix A: File Reference

File

Lines

Purpose

BrisqueAlgorithm.hpp

C++ wrapper class

main.cpp

C++ CLI entry point

CMakeLists.txt

C++ build config

BrisqueScore.cs

113

C# P/Invoke wrapper

.csproj

C# project config

Total Implementation: ~250 lines of production code

Appendix B: BRISQUE Algorithm Overview

Algorithm Pipeline

Preprocessing: Convert to grayscale, compute local mean/variance
MSCN Coefficients: Mean Subtracted Contrast Normalized values
Feature Extraction: 36 features from GGD fitting
Normalization: Scale using pre-computed ranges
Prediction: SVM regression outputs quality score

Model Details

Parameter

Value

SVM Type

EPS_SVR

Kernel

RBF (Radial Basis Function)

1024

gamma

0.05

epsilon

0.001

Support Vectors

774

Features

Appendix C: Glossary

Term

Definition

BRISQUE

Blind/Referenceless Image Spatial Quality Evaluator

P/Invoke

Platform Invocation Services - .NET native interop

RAII

Resource Acquisition Is Initialization (C++ pattern)

IQA

Image Quality Assessment

NSS

Natural Scene Statistics

MSCN

Mean Subtracted Contrast Normalized

SVM

Support Vector Machine

vcpkg

Microsoft C++ package manager

WinUI

Windows UI Library for modern Windows apps

Document Version: 1.0 Last Updated: January 2026 Repository: LuxoriaSoft/brisque_impl_netlib

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Last updated 27 minutes ago

Good afternoon

hashtagDocument Information

hashtagTable of Contents

hashtag1. Executive Summary

hashtagProject Goal

hashtagKey Achievements

hashtagTrade-off Summary

hashtag2. Project Context

hashtag2.1 What is BRISQUE?

hashtag2.2 Why This Refactoring?

hashtag2.3 Original Implementation (C++)

hashtag2.4 Target Implementation (C#)

hashtag3. Architecture Comparison

hashtag3.1 C++ Architecture

hashtag3.2 C# Architecture

hashtag3.3 Key Architectural Differences

hashtag4. Technical Trade-offs Analysis

hashtag4.1 Interop Strategy: P/Invoke vs Pure Managed

hashtagOption A: Pure C# Reimplementation

hashtagOption B: P/Invoke Wrapper (Selected)

hashtag4.2 Library Embedding vs External Dependencies

hashtagOption A: External DLL Reference

hashtagOption B: Embedded Resources (Selected)

hashtag4.3 Static vs Dynamic Linking (Native Side)

hashtag5. Design Decisions

hashtag5.1 API Surface Design

hashtagC++ Original API

hashtagC# Wrapper API

hashtagDesign Changes Explained

hashtag5.2 Native Function Signatures

hashtag5.3 Namespace Design

hashtag6. Memory Management

hashtag6.1 C++ Memory Model

hashtag6.2 C# Memory Model

hashtag6.3 Memory Ownership

hashtag6.4 Safety Measures

hashtag7. Platform Strategy

hashtag7.1 Windows-Focused Design

hashtag7.2 Architecture Detection

hashtag7.3 Supported Configurations

hashtag7.4 Native Library Loading

hashtag8. Distribution Strategy

hashtag8.1 NuGet Package Structure

hashtag8.2 Installation

hashtag8.3 Usage in Luxoria

hashtag8.4 Model Files

hashtag9. Error Handling

hashtag9.1 Validation Layer

hashtag9.2 Exception Types

hashtag9.3 Comparison with C++

hashtag10. API Design

hashtag10.1 Side-by-Side Comparison

hashtag10.2 API Improvements in C#

hashtag11. Build System

hashtag11.1 C++ Build (CMake + vcpkg)

hashtag11.2 C# Build (MSBuild)

hashtag11.3 CI/CD Pipeline

hashtag12. Lessons Learned

hashtag12.1 What Worked Well

hashtag12.2 Challenges Overcome

hashtag12.3 TODO / Technical Debt

hashtag13. Conclusion

hashtag13.1 Project Success Metrics

hashtag13.2 Final Architecture

hashtag13.3 Key Takeaways

hashtagAppendix A: File Reference

hashtagAppendix B: BRISQUE Algorithm Overview

hashtagAlgorithm Pipeline

hashtagModel Details

hashtagAppendix C: Glossary

Document Information

Table of Contents

1. Executive Summary

Project Goal

Key Achievements

Trade-off Summary

2. Project Context

2.1 What is BRISQUE?

2.2 Why This Refactoring?

2.3 Original Implementation (C++)

2.4 Target Implementation (C#)

3. Architecture Comparison

3.1 C++ Architecture

3.2 C# Architecture

3.3 Key Architectural Differences

4. Technical Trade-offs Analysis

4.1 Interop Strategy: P/Invoke vs Pure Managed

Option A: Pure C# Reimplementation

Option B: P/Invoke Wrapper (Selected)

4.2 Library Embedding vs External Dependencies

Option A: External DLL Reference

Option B: Embedded Resources (Selected)

4.3 Static vs Dynamic Linking (Native Side)

5. Design Decisions

5.1 API Surface Design

C++ Original API

C# Wrapper API

Design Changes Explained

5.2 Native Function Signatures

5.3 Namespace Design

6. Memory Management

6.1 C++ Memory Model

6.2 C# Memory Model

6.3 Memory Ownership

6.4 Safety Measures

7. Platform Strategy

7.1 Windows-Focused Design

7.2 Architecture Detection

7.3 Supported Configurations

7.4 Native Library Loading

8. Distribution Strategy

8.1 NuGet Package Structure

8.2 Installation

8.3 Usage in Luxoria

8.4 Model Files

9. Error Handling

9.1 Validation Layer

9.2 Exception Types

9.3 Comparison with C++

10. API Design

10.1 Side-by-Side Comparison

10.2 API Improvements in C#

11. Build System

11.1 C++ Build (CMake + vcpkg)

11.2 C# Build (MSBuild)

11.3 CI/CD Pipeline

12. Lessons Learned

12.1 What Worked Well

12.2 Challenges Overcome

12.3 TODO / Technical Debt

13. Conclusion

13.1 Project Success Metrics

13.2 Final Architecture

13.3 Key Takeaways

Appendix A: File Reference

Appendix B: BRISQUE Algorithm Overview

Algorithm Pipeline

Model Details

Appendix C: Glossary