UE5 ColorTransfer plugin document

1. Introduction

ColorTransfer is an Unreal Engine plugin that performs real-time color transfer between images. Given a reference image, it transfers the color style to the scene viewport in real time.

It has the following features:

1. Real-time color transfer applied as a post-process pass
2. Reference image hot-swap at runtime via Blueprint
3. EMA smoothing to suppress flicker
4. Works in editor viewport, PIE, and packaged builds
5. Support Android / iOS / Win64 / Linux / LinuxArm64 / Mac

1.1 Quick Start

1.1.1 Direct way

1. Install the plugin and enable it in Plugins window
2. Place a ColorTransferActor in the level (found in the Place Actors panel under VFX category)
3. Assign a ReferenceImage texture to the actor
4. Check Enable to activate the effect

1.1.2 New BP inherent from ColorTransferActor

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2. AColorTransferActor

Place a ColorTransferActor in your level. It drives the color transfer effect for the entire scene.

2.1 Properties

Property	Type	Default	Description
Enable	bool	false	Toggles the effect on/off. Can be changed at runtime via SetEnable()
Cal Each Frame	bool	false	When true, reference stats are re-computed every frame (useful for animated reference textures). When false, stats are cached after first computation
Smoothing Alpha	float (0.0–1.0)	0.1	Smoothing factor for scene statistics. 0.0 = frozen, 1.0 = instant (may flicker). Recommended: 0.05 ~ 0.2
Reference Image	UTexture2D*	nullptr	The reference image whose color style will be transferred to the scene

2.2 Blueprint Functions

Node	Signature	Type	Description
Set Enable	void SetEnable(bool bEnable)	BlueprintCallable	Enables or disables the effect at runtime
Set Reference Image	void SetReferenceImage(UTexture2D* NewImage)	BlueprintCallable	Swaps the reference image at runtime

2.3 Typical Blueprint Usage

SetReferenceImage(NewStyleTexture) → SetEnable(true)

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3. Reference Image Requirements

The reference image texture must meet these requirements:

Requirement	Value
Format	RGBA8
Compression	Uncompressed(RGBA8)

If the format is incorrect, the plugin will log a warning:

reference texture 'MyTexture' is not PF_B8G8R8A8 — import with no compression and no alpha override.

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4. Logging

The plugin logs to the LogColorTransfer category. Verbose logs are disabled by default.

Enable verbose logging via console command:

Log LogColorTransfer Verbose

Or in DefaultEngine.ini:

[Core.Log]
LogColorTransfer=Verbose

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5. Platform Notes

On mobile (Android / iOS), the transfer pass is applied after Tonemap instead of MotionBlur.

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6. Troubleshooting

• Effect doesn’t appear: Ensure Enable is checked and a valid Reference Image (BGRA8, uncompressed) is assigned. Wait one frame after enabling.
• Flickering: Lower Smoothing Alpha (e.g. 0.05).

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Plugin Version: 1.0

Engine Version: 5.7/5.6/5.5

Platforms: Win64 / Linux / LinuxArm64 / Mac / iOS / Android