FlipBinding.CSharp

A C# binding library for FLIP v1.7. Compatible with Unity.

Installation

NuGet

dotnet add package FlipBinding.CSharp

NuGetForUnity

1. If you are using macOS and have a ProjectSettings/Packages/com.github-glitchenzo.nugetforunity/NativeRuntimeSettings.json file created with NuGetForUnity v4.5.0 or earlier, insert the following configuration entry into the file:

   {
     "configurations": [
       {
         "cpuArchitecture": "AnyCPU",
         "editorCpuArchitecture": "AnyCPU",
         "editorOperatingSystem": "OSX",
         "runtime": "osx",
         "supportedPlatformTargets": [
           "StandaloneOSX"
         ]
       }
     ]
   }

2. Open the NuGetForUnity window via NuGet > Manage NuGet Packages, search for "FlipBinding.CSharp", and click Install.

Important

When running on the Ubuntu 22.04 image (e.g., GameCI provided images), the GLIBCXX_3.4.32 (GCC 13+) required by FLIP's native libraries is missing. So, you will need to create a custom Docker image that includes libstdc++6 from GCC 13.

Usage

LDR Image Comparison

using FlipBinding.CSharp;

// Image data is in linear RGB interleaved format [r,g,b,r,g,b,...]
float[] reference = /* reference image */;
float[] test = /* test image */;

var result = Flip.Evaluate(reference, test, width, height);

// Mean error value (0-1, higher means greater difference)
Console.WriteLine($"Mean FLIP error: {result.MeanError}");

// Get per-pixel error value
float pixelError = result.GetPixel(x, y);

HDR Image Comparison

For HDR image comparison, specify useHdr: true:

var result = Flip.Evaluate(reference, test, width, height,
      useHdr: true, tonemapper, startExposure, stopExposure, numExposures);

Magma Color Map

You can get the error map as an RGB color map for visualization:

var result = Flip.Evaluate(reference, test, width, height, applyMagmaMap: true);

// Get RGB values
var (r, g, b) = result.GetPixelRgb(x, y);

API Reference

Flip.Evaluate

public static FlipResult Evaluate(
    float[] reference,           // Reference image (linear RGB)
    float[] test,                // Test image (linear RGB)
    int width,                   // Image width
    int height,                  // Image height
    bool useHdr = false,         // Use HDR-FLIP if true
    float ppd = 67.02f,          // Pixels per degree. Default value based on: 0.7m viewing distance, 3840px resolution, 0.7m monitor width.
    Tonemapper tonemapper = Tonemapper.Aces,
    float startExposure = float.PositiveInfinity,
    float stopExposure = float.PositiveInfinity,
    int numExposures = -1,
    bool applyMagmaMap = false   // Apply Magma color map
)

Note

• Image data must be in linear RGB. If using sRGB, convert beforehand
• Array size must be width * height * 3 (RGB interleaved format)

PPD (Pixels Per Degree) Calculation

You can calculate PPD from viewing conditions:

float ppd = Flip.CalculatePpd(
    viewingDistance: 0.5f,   // Viewing distance (meters)
    resolutionX: 2560,       // Horizontal resolution (pixels)
    monitorWidth: 0.6f       // Monitor width (meters)
);

var result = Flip.Evaluate(reference, test, width, height, ppd: ppd);

License

This library is licensed under the MIT License.

This library includes binary distributions of FLIP v1.7, which is licensed under the BSD 3-Clause License by NVIDIA CORPORATION & AFFILIATES. See THIRD-PARTY-NOTICES.txt for details.