Custom Tone Mapping for URP

This package extends URP by adding custom tone mapping algorithms, providing more options for different visual requirements and workflows.

GT7 Tone Mapping Sample

Since adding new tone mapping functions to URP is not officially supported through Unity's API, integration requires either URP modifications or a renderer feature. Please see the Integration Guide for details

Features

Additional tone mapping algorithms
HDR display output compatibility
- Runtime LUT generation supports variable peak brightness configurations
Custom LUT support
- Allows use of external LogC-encoded lookup tables
Configurable LUT size (32³ to 65³) for quality/memory tradeoff
- Found in the Additional Properties section of the Custom Tone Mapping component

Prerequisites

Unity 6 or later
Universal Render Pipeline

Installation

Install via OpenUPM:

Package is available on OpenUPM. If you have openupm-cli installed, run this in your Unity project root:
```
openupm add net.aki-null.tonemapping
```
To update, specify the version you want:
```
openupm add [email protected]
```

Install via UPM (Git URL):

Open Window > Package Manager
Click the + button in the top-left corner
Select Add package from git URL
Enter: https://github.com/aki-null/CustomToneMappingURP.git
Follow the Integration Guide

Alternatively, add it to your Packages/manifest.json:

{
    "dependencies": {
        "net.aki-null.tonemapping": "https://github.com/aki-null/CustomToneMappingURP.git"
    }
}

Usage

Add a Tonemapping volume component
- Set to None when using the Renderer Feature method
- Set to Custom when using the URP modification method
Add a Custom Tone Mapping volume component and select a mode
Add the mode-specific volume component to configure parameters
- Each mode requires its own dedicated volume component (e.g., GT Tone Mapping, GT7 Tone Mapping, AgX Tone Mapping, etc.)

Technical Details

Rather than performing tone mapping calculations directly on the GPU during rendering, the system pre-computes the tone mapping results into a 3D lookup table on the CPU.

The workflow operates as follows: Volume components supply tone mapping parameters, which the system uses to generate a 3D LUT. This LUT is stored as a 2D texture strip and uploaded to the GPU. The LUT is regenerated automatically when parameters change.

During rendering, URP's post-processing pipeline samples from this pre-computed LUT to apply the tone mapping.

Modes

GT Tone Mapping

Designed by Polyphony Digital for Gran Turismo Sport. Initially presented at CEDEC 2017 and later at SIGGRAPH Asia 2018.

GT7 Tone Mapping

Designed by Polyphony Digital for Gran Turismo 7. Presented at SIGGRAPH 2025.

AgX

Designed by Troy Sobotka. The LUT generation is based on Eary Chow's version.

Custom LUT

When Custom LUT is selected, assign a LUT texture (Alexa LogC El1000) in the Custom Tone Mapping component. Note that Custom LUT mode uses a static LUT and does not support variable peak brightness like the other modes.

Integration Guide

Method 1: Renderer Feature (No URP Modification)

The Custom Tone Mapping Renderer Feature enables custom tone mapping without modifying URP packages. This approach is suitable for:

Projects that cannot modify URP source code
Testing custom tone mapping before committing to URP modifications
Maintaining easier Unity version upgrades

Limitations

Incompatible with LDR color grading
Less efficient than native integration due to additional rendering pass overhead

Setup

Add Custom Tone Mapping Renderer Feature to your Universal Renderer Data
Set URP's Tonemapping mode to None in your Volume Profile
Add a Custom Tone Mapping volume component and select a mode
Add the mode-specific volume component to configure parameters
- Each mode requires its own dedicated volume component (e.g., GT Tone Mapping, GT7 Tone Mapping, AgX Tone Mapping, etc.)

Technical Details

The renderer feature injects a tone mapping pass into the render pipeline by intercepting the color grading LUT after URP's LUT generation pass and applying custom tone mapping. This approach provides better integration with the pipeline compared to directly tone mapping the framebuffer.

Method 2: URP Package Modification (Recommended)

Modifying the URP package provides native integration with optimal performance and full compatibility with all URP features.

1. Add Assembly Reference

File: Packages/com.unity.render-pipelines.universal/Runtime/Unity.RenderPipelines.Universal.Runtime.asmdef

Add the custom tonemapper assembly reference to the references array:

     "references": [
         "GUID:df380645f10b7bc4b97d4f5eb6303d95",
         "GUID:69257879134bba646869b21467b3338d",
         "GUID:ab67fb10353d84448ac887a7367cbda8",
         "GUID:7dbf32976982c98448af054f2512cb79",
         "GUID:d8b63aba1907145bea998dd612889d6b",
         "GUID:2665a8d13d1b3f18800f46e256720795",
         "GUID:4fd6538c1c56b409fb53fdf0183170ec",
         "GUID:86bc95e6fdb13ff43aa04316542905ae",
         "GUID:d04eb9c554ad44ceab303cecf0c0cf82",
         "GUID:214c0945bb158c940aada223f3223ee8",
+        "net.aki-null.ToneMapping.URP",
         "GUID:c49c619b6af2be941af9bcbca2641964"
     ],

2. Add Custom Tonemapping Mode

File: Packages/com.unity.render-pipelines.universal/Runtime/Overrides/Tonemapping.cs

Around line 27

 namespace UnityEngine.Rendering.Universal
 {
     [Serializable]
     public enum TonemappingMode
     {
         /// <summary>
         /// Use this option if you do not want to apply tonemapping
         /// </summary>
         None,

         /// <summary>
         /// Use this option if you only want range-remapping with minimal impact on color hue and saturation.
         /// It is generally a great starting point for extensive color grading.
         /// </summary>
         Neutral, // Neutral tonemapper

         /// <summary>
         /// Use this option to apply a close approximation of the reference ACES tonemapper for a more filmic look.
         /// It is more contrasted than Neutral and has an effect on actual color hue and saturation.
         /// Note that if you use this tonemapper all the grading operations will be done in the ACES color spaces for optimal precision and results.
         /// </summary>
-        ACES // ACES Filmic reference tonemapper (custom approximation)
+        ACES, // ACES Filmic reference tonemapper (custom approximation)
+        Custom
    }

3. Update UberPost Shader

File: Packages/com.unity.render-pipelines.universal/Shaders/PostProcessing/UberPost.shader

Around line 7:

 HLSLINCLUDE
     #pragma exclude_renderers gles
-    #pragma multi_compile_local_fragment _ _HDR_GRADING _TONEMAP_ACES _TONEMAP_NEUTRAL
+    #pragma multi_compile_local_fragment _ _HDR_GRADING _TONEMAP_ACES _TONEMAP_NEUTRAL _TONEMAP_CUSTOM
     #pragma multi_compile_local_fragment _ _FILM_GRAIN
     #pragma multi_compile_local_fragment _ _DITHERING
     #pragma multi_compile_local_fragment _ _GAMMA_20 _LINEAR_TO_SRGB_CONVERSION

Around line 33 (include order matters):

     #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
+    #include "Packages/net.aki-null.tonemapping/Runtime/URP/Shaders/TonemapParams.hlsl"
     #include "Packages/com.unity.render-pipelines.universal/Shaders/PostProcessing/Common.hlsl"
     #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Debug/DebuggingFullscreen.hlsl"
     #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/DynamicScalingClamping.hlsl"
     #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/FoveatedRendering.hlsl"

4. Update LutBuilderHdr Shader

File: Packages/com.unity.render-pipelines.universal/Shaders/PostProcessing/LutBuilderHdr.shader

Around line 4 (include order matters):

     HLSLINCLUDE
-        #pragma multi_compile_local _ _TONEMAP_ACES _TONEMAP_NEUTRAL
+        #pragma multi_compile_local _ _TONEMAP_ACES _TONEMAP_NEUTRAL _TONEMAP_CUSTOM
         #pragma multi_compile_local_fragment _ HDR_COLORSPACE_CONVERSION

         #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
+        #include "Packages/net.aki-null.tonemapping/Runtime/URP/Shaders/TonemapParams.hlsl"
         #include "Packages/com.unity.render-pipelines.universal/Shaders/PostProcessing/Common.hlsl"
         #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/ACES.hlsl"
         #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"
 #if defined(HDR_COLORSPACE_CONVERSION)
         #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/HDROutput.hlsl"
 #endif

Around line 202:

         float3 Tonemap(float3 colorLinear)
         {
             #if _TONEMAP_NEUTRAL
             {
                 colorLinear = NeutralTonemap(colorLinear);
             }
             #elif _TONEMAP_ACES
             {
                 // Note: input is actually ACEScg (AP1 w/ linear encoding)
                 float3 aces = ACEScg_to_ACES(colorLinear);
                 colorLinear = AcesTonemap(aces);
             }
+            #elif _TONEMAP_CUSTOM
+            #include "Packages/net.aki-null.tonemapping/Runtime/URP/Shaders/Tonemap.hlsl"
             #endif

             return colorLinear;
         }

         float3 ProcessColorForHDR(float3 colorLinear)
         {
             #ifdef HDR_COLORSPACE_CONVERSION
                 #ifdef _TONEMAP_ACES
                 float3 aces = ACEScg_to_ACES(colorLinear);
                 return HDRMappingACES(aces.rgb, PaperWhite, MinNits, MaxNits, RangeReductionMode, true);
                 #elif _TONEMAP_NEUTRAL
                 return HDRMappingFromRec2020(colorLinear.rgb, PaperWhite, MinNits, MaxNits, RangeReductionMode, HueShift, true);
+                #elif _TONEMAP_CUSTOM
+                #include "Packages/net.aki-null.tonemapping/Runtime/URP/Shaders/TonemapHdr.hlsl"
                 #else
                 // Grading finished in Rec2020, converting to the expected color space and [0, 10k] nits range
                 return RotateRec2020ToOutputSpace(colorLinear) * PaperWhite;
                 #endif
             #endif

             return colorLinear;
         }

5. Update Common Shader Inlcude

File: Packages/com.unity.render-pipelines.universal/Shaders/PostProcessing/Common.hlsl

Around line 108 in ApplyTonemap function:

 half3 ApplyTonemap(half3 input)
 {
 #if _TONEMAP_ACES
     float3 aces = unity_to_ACES(input);
     input = AcesTonemap(aces);
 #elif _TONEMAP_NEUTRAL
     input = NeutralTonemap(input);
+#elif _TONEMAP_CUSTOM
+#include "Packages/net.aki-null.tonemapping/Runtime/URP/Shaders/TonemapLdr.hlsl"
 #endif

     return saturate(input);
}

6. Add C# Integration Points

File: Packages/com.unity.render-pipelines.universal/Runtime/Passes/PostProcessPassRenderGraph.cs

Around line 1922 in RenderUberPost method:

                         switch (data.toneMappingMode)
                         {
                             case TonemappingMode.Neutral: material.EnableKeyword(ShaderKeywordStrings.TonemapNeutral); break;
                             case TonemappingMode.ACES: material.EnableKeyword(ShaderKeywordStrings.TonemapACES); break;
+                            case TonemappingMode.Custom: CustomToneMapping.URP.UrpBridge.PrepareMaterial(material, data.cameraData.isHDROutputActive ? data.cameraData.hdrDisplayInformation : null); break;
                             default: break; // None
                         }

File: Packages/com.unity.render-pipelines.universal/Runtime/Passes/ColorGradingLutPass.cs

Around line 250 in ExecutePass method:

                     switch (tonemapping.mode.value)
                     {
                         case TonemappingMode.Neutral: material.EnableKeyword(ShaderKeywordStrings.TonemapNeutral); break;
                         case TonemappingMode.ACES: material.EnableKeyword(allowColorGradingACESHDR ? ShaderKeywordStrings.TonemapACES : ShaderKeywordStrings.TonemapNeutral); break;
+                        case TonemappingMode.Custom: CustomToneMapping.URP.UrpBridge.PrepareMaterial(material, passData.cameraData.isHDROutputActive ? passData.cameraData.hdrDisplayInformation : null); break;
                         default: break; // None
                     }

License

This project is licensed under the MIT License – see LICENSE.md.

This project includes third-party code under its own licenses. See THIRD_PARTY_NOTICES.md.

Name		Name	Last commit message	Last commit date
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Editor		Editor
Runtime		Runtime
Tests		Tests
CHANGELOG.md		CHANGELOG.md
CHANGELOG.md.meta		CHANGELOG.md.meta
Editor.meta		Editor.meta
LICENSE.md		LICENSE.md
LICENSE.md.meta		LICENSE.md.meta
README.md		README.md
README.md.meta		README.md.meta
Runtime.meta		Runtime.meta
THIRD_PARTY_NOTICES.md		THIRD_PARTY_NOTICES.md
THIRD_PARTY_NOTICES.md.meta		THIRD_PARTY_NOTICES.md.meta
Tests.meta		Tests.meta
package.json		package.json
package.json.meta		package.json.meta

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Custom Tone Mapping for URP

Table of Contents

Features

Prerequisites

Installation

Usage

Technical Details

Modes

GT Tone Mapping

GT7 Tone Mapping

AgX

Custom LUT

Integration Guide

Method 1: Renderer Feature (No URP Modification)

Limitations

Setup

Technical Details

Method 2: URP Package Modification (Recommended)

1. Add Assembly Reference

2. Add Custom Tonemapping Mode

3. Update UberPost Shader

4. Update LutBuilderHdr Shader

5. Update Common Shader Inlcude

6. Add C# Integration Points

License

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Custom Tone Mapping for URP

Table of Contents

Features

Prerequisites

Installation

Usage

Technical Details

Modes

GT Tone Mapping

GT7 Tone Mapping

AgX

Custom LUT

Integration Guide

Method 1: Renderer Feature (No URP Modification)

Limitations

Setup

Technical Details

Method 2: URP Package Modification (Recommended)

1. Add Assembly Reference

2. Add Custom Tonemapping Mode

3. Update UberPost Shader

4. Update LutBuilderHdr Shader

5. Update Common Shader Inlcude

6. Add C# Integration Points

License

About

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