Texturing: How to Pack Multiple Black and White Textures into Single RGB Texture with Photoshop (w/UE5 Example)

Texture optimization is key in game development for improving performance.

One of these methods is to pack separate black-and-white textures such as texture masks, roughness, metallic or ambient occlusion maps into the Red, Green and Blue channels of one texture file.

In this post I will show you how to do this using Photoshop.

Video Tutorial

Step 1: Prepare Your Textures

Start with 3 grayscale textures you want to pack. These could be:

• Texture masks (e.g., dirt, wear, edge damage)
• Roughness maps
• Metallic maps
• Ambient occlusion maps

Or any combination, as long as they are black-and-white and intended for linear color space.

Open all three textures in Photoshop to check their dimensions. Go to Image > Image Size for each one. In this example, the textures are 2K (2048 × 2048 pixels).

Here are the 3 texture masks I will be using to pack into a single texture:

Step 2: Create a New RGB Document

Create a new file that matches the dimensions of your source textures:

• Go to File > New
• Set Width and Height to 2048 pixels (or your texture size)
• Resolution: 72 ppi
• Color Mode: RGB Color
• Bit Depth: 8 bit

Click Create.

This new document will become your packed texture.

Step 3: Pack Each Texture into a Channel

Switch to the Channels:

• Go to your first source texture
• Press Ctrl + A (Select All) to select the entire canvas
• Press Ctrl + C (Copy)
• Switch to your new document
• Select the Red channel only
• Press Ctrl + V (Paste)

The first texture now lives in the Red channel.

Repeat the same steps for two other additional textures for the Green and Blue channels.

To preview the combined result, click the RGB. You'll see a colorful mix, this is normal as each channel holds independent grayscale texture data.

Step 4: Export the Packed Texture

• Go to File > Export > Export As
• Format: PNG
• Keep dimensions at 2048 × 2048 (or downscale to 1K/512 if need it)
• Disable transparency
• Name it clearly
• Export to your desired folder

Step 5: Import and Set Up in Unreal Engine 5

• Import the packed texture into UE5
• Double-click the imported texture to open the Texture Editor
• Critical step: Uncheck sRGB
• Save the texture

Step 6: Using the Packed Texture in a Material

In UE5, I've set up basic blend between 2 textures using a Lerp.

Then brought it the packed mask texture and used a Component Mask (converted to parameter) in order to let me select individual RGB channels through the Material Instance.

Test all the channels of the packed masked texture before using it:

Benefits and Tips

Performance gain: One texture sample instead of three.

Common packing conventions (for ARM textures):

• Red: Ambient Occlusion
• Green: Roughness (often preferred here due to better bit allocation in some compressions)
• Blue: Metallic

You can add a fourth map to the Alpha channel if needed, but this switches compression to DXT5 (higher memory use).

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