UE4 – Quick fix for normal map encoding

Software:
Unreal Engine 4.25 | Photoshop 2020

Quick UE normal map tip:
If you load a normal map into a UE material and the result appears inverted, i.e. holes instead of bumps or the other way:

The quick fix:

1. In the texture settings, check the Flip Green Channel option and save it:

The deep fix:
* This can be performed an automated action on multiple files

1. Open the normal map in Photoshop
2. In the Channels panel, select the Green channel
3. Press Ctrl + I,
   Or Select Image > Adjustments > Invert
   To invert the green channel.
4. Save the texture and reload into Unreal Engine.
   

Inverted normal map:

Fixed normal map:

Related:
UE4 Bump map
UE4 – Procedural Bump Normals