Create a multi-frequency normal map

A multi-frequency normal map is basically just a map composed of multiple detail levels. Each detail level gets preprocessed by a low-pass filter to sample the normal vectors in descending frequency ranges and then combined to a single normal map.

 

Step 1

Select an input texture and go to the Normal tab 

 

Step 2

Create three new layers 

 

Step 3

Setting up the filters

1. Add a Diffuse-To-Normal filter to the top-most layer. This layer will reflect the high-frequencies and shows the fine details.
2. Add a Gaussian Blur filter and a Diffuse-To-Normal filter to the middle layer. This layer will reflect the medium-frequencies and shows medium details.
3. Add a Gaussian Blur filter and a Diffuse-To-Normal filter to the bottom layer. This layer will reflect the low-frequencies and shows just the very slow-changing surface characteristics.
4. Set the layer blend mode to Linear Light to appropriately mix the layer outputs

 

 

Step 4

Set the Gaussian blur radius to appropriate values.

 

Step 5

Fine-tune the settings until the output fits your needs.