Frequency separation retouching cheatsheet

Duplicate the layer twice. Perform these in each layer:

Lower layer

• Apply Gaussian Blur

Upper layer

• Set layer mask to Linear light
• Image → Apply Image
  • Layer: (select the lower layer)
  • Blending mode: Subtract
  • Scale: 2
  • Offset: 128

• https://phlearn.com/amazing-power-frequency-separation-retouching-photoshop